Horticulture

This experiment was conducted at least twice. Calculation of the EC50 values for potassium phosphite of each isolate was determined as described in Adaskaveg et al. . Briefly, the EC50 values were determined by fitting regression lines of the natural log-transformed phosphite concentration against the logit-transformed percent inhibition as compared with the control for each isolate. Regression equations were then solved for concentration at 50% inhibition using Microsoft Excel . The EC50 values for mefenoxam , fluopicolide , and oxathiapiprolin , currently used to control diseases caused by oomycete pathogens, were determined using the spiral gradient dilution method described by Förster et al. . Mefenoxam, oxathiapiprolin, and fluopicolide were dissolved in sterile water to make the corresponding stock solutions at 50, 5, and 100 µg/ml, respectively. Each fungicide was radially applied to a 15-cm 10% cV8A plate using a spiral plater . Isolates were grown for 7 days in the dark at 22°C on 10% cV8A media. Cultures were then cut into strips and placed between sterile hydrophilic cellophane strips on new 10% cV8A plates. Plates were incubated for another 7 days in the dark at 22°C or until the mycelium had evenly covered the strips. Mycelium-covered cellophane strips were then radially applied across the fungicide concentration gradient on the spiral gradient dilution fungicide plate.

The ranges of concentrations used were between 0.0025 to 0.6837 µg/ml , 0.0038 to 1.4054 µg/ml , procona London container and 0.0002 to 0.0572 µg/ml for mefenoxam, fluopicolide, and oxathiapiprolin, respectively. For each isolate, duplicated strips were placed at the opposite location on each spiral gradient dilution fungicide plate . Controls consisted of cV8A plates spirally plated with water, to which cellophane strips were placed as described above. Plates were incubated in the dark at 22°C. Two independent experiments were conducted. Two days after incubation, the mycelial growth of each isolate in each of the control plates was measured. The location where mycelial growth was inhibited by 50%, compared with growth on the control plates, was determined. This distance was used to determine the local fungicide concentration on the agar at the location of 50% inhibition using the SGE software . The EC50 values for each fungicide were calculated using the spiral gradient endpoint software as described in Förster et al. .Nine-month-old avocado rootstocks liners were inoculated with P. cinnamomi colonized millet seed. Millet inoculum was prepared according to the method of Drenth and Sendall . Briefly, 175 ml distilled water was added to 144 g of millet seed. Excess water was poured off and moistened millet was autoclaved in a 250 ml volumetric flask.

Autoclaving was repeated the following day. For each isolate, ten plugs of 6-mm-diameter were cut from the margin of a 4-day-old colony of P. cinnamomi plate and were added to the flask containing the sterilized millet seeds. Inoculated millet was incubated in the dark at 25°C for 21 days. The millet was then harvested, weighed, and homogenized in a plastic bag. A total of 4.4 g of inoculum per plant was used for inoculation by placing the inoculated millet around the root collar. Combination isolate inoculum was produced by thoroughly mixing equal amounts of each corresponding isolate inoculated millet seeds together. Dusaâ and PS.54 ungrafted clonal rootstocks were inoculated with individual isolates, a combination of Northern California isolates , a combination of Southern California isolates , and a combination of all isolates . Control plants were treated with uninoculated millet seeds that were sterilized and prepared in the same manner as the inoculated millet seeds. The experiment was conducted in a greenhouse using a randomized complete block design with five replicates per treatment. The average maximum temperature in the greenhouse was 28°C with an average minimum temperature of 14°C. To confirm that plants were successfully infected, roots samples were excised from harvested plants and 10 to 20 segments per plant were surface sterilized in 70% ethanol and plated onto the PARPH-V8 Phytophthora-selective media identified by Paglaccia et al. .

The A2 clade I contained P. cinnamomi isolates collected from 1989 to 2010, whereas the A2 clade II only contained a unique set of isolates collected in 2009 and 2010 from Southern California avocado growing regions. This study reported significant differences in vegetative growth, fungicide sensitivity, and virulence among all the isolates tested. Moreover, Southern isolates were less sensitive to potassium phosphite and have slower growth rate at 22℃ whereas Northern isolates were more sensitive to potassium phosphite and have higher growth rates. This trend observed suggests a correlation between mycelial growth rate at 22℃and potassium phosphite sensitivity with specific group of isolates. The group of Northern isolates corresponding to the A2 clade I mating type group exhibited higher mycelial growth rates than the Southern group of isolates at 22°C independent of the nutrient media used . Consistent with the results of Zentmyer et al. , there was a significant effect of nutrient media and mycelial growth rate of the P. cinnamomi study isolates, however this effect did not alter the split of the Northern and Southern isolates by their growth rate. The higher sensitivity of the A2 clade I isolates, collected from Northern California, to higher temperatures when compared with the Southern isolates might be explained by the fact that the median temperature is higher in Southern than in Northern California throughout the year.Previous studies reported phenotypic differences in colony morphology, growth rate, and optimum growth temperature among P. cinnamomi isolates, however the majority of these studies compared isolates from different mating types, origin , and host plants . Only a few studies have included P. cinnamomi associated with avocado when assessing phenotypic variability . In the majority of these studies, the authors could not assign a phenotypic trait to a specific group of isolates. Others have reported varying results on the linkage between genotype groups and colony morphology. Dobrowolski et al. reported that colony morphology of Australian P. cinnamomi isolates grouped with a particularly genotype. In contrast to these results, colony morphology among the twelve isolates tested in this study did not vary significantly. Lopez-Herrera and Perez-Jimenez reported significant differences on colony morphology among P. cinnamomi A2 isolates collected from avocado trees in Spain, but these isolates did not exhibit significant differences on mycelial growth rates. California produces 95% of the avocado crop for the U.S.A and PRR caused by P. cinnamomi is responsible for commercial losses totaling $40 million annually statewide. Mefenoxam and phosphite applications are widely used to prevent and combat this disease , however, there is a notably preference for phosphite products over mefenoxam among the growers and this is particularly true for California growers. This preference could explain why mefenoxam-resistant isolates were not found in this study. Moreover, the range of the EC50 values for mefenoxam was consistent with previous values reported for P. cinnamomi in the U.S.A . Duan et al. reported minor variation in sensitivity to mefenoxam among P. cinnamomi isolates collected from diseased ornamental plants in South Carolina. The EC50 values of the majority of these isolates were less than 0.1 µg/ml. Hu et al. found that there were more variations in mefenoxam sensitivity among P. cinnamomi isolates collected from different host species than from the same host.

In this study, cut flower transport bucket the authors classified isolates as sensitive to mefenoxam when their EC50 values ranged from 0.01 to 0.02 µg/ml and as intermediate when EC50 values ranged from 0.03 to 0.08 µg/ml. The EC50 values for mefenoxam in this study were also less than 0.1 µg/ml suggesting that the repeated use of this fungicide to control PRR in nurseries and avocado orchards does not appear to have reduced the mefenoxam sensitivity of P. cinnamomi isolates. In contrast to mefenoxam, we detected a significant variability among the isolates in potassium phosphite sensitivity but we did not find potassium phosphite-resistant isolates. The Northern isolates corresponding to the A2 clade I group had EC50 values of < 34.1 µg/ml, whereas the Southern isolates had EC50 values of > 98.9 µg/ml. It is worrisome that the Southern group of isolates including the A2 clade II isolates that exhibited more virulence in the moderate resistant Dusaâ, which is the current industry standard rootstock among California avocado growers, were less sensitive to potassium phosphite. Their higher EC50 values could represent a selection from higher doses of potassium phosphite being necessary to suppress and control avocado root rot where these isolates are present. A more detailed study with a larger number of isolates and history of phosphonate applications in the field are needed it to test this hypothesis. Dobrowolski et al. demonstrated that P. cinnamomi isolates exposed to long periods of phosphite treatment in avocado orchards in Australia exhibited reduced sensitivity to phosphite when evaluated on avocado, lupin, and eucalyptus suggesting the onset of resistance to this fungicide. Similar results have been reported for P. cinnamomi isolates from avocado orchards in South Africa . This study reports for the first time, the presence of P. cinnamomi isolates, collected from PRR diseased avocado roots in California, that are less sensitive to potassium phosphate. To help delay the development of phosphite-resistant P cinnamomi isolates, care should be taken to alternate or mix phosphite products with other effective fungicides with different mode of action to control avocado PRR. Phosphite and mefenoxam rotation with alternative fungicides is commonly used to prevent or reduce the emergence of Phytophthora resistant isolates , however there are no other fungicides tested or registered to control P. cinnamomi in avocado. Fluopicolide and oxathiapiprolin are two new oomycete-targeted fungicides that have been tested for several Phytophthora spp., but not for P. cinnamomi . In this study, we report for the first time that the EC50 values for mycelial growth inhibition of P. cinnamomi avocado isolates are within the range of the EC50 values reported for other Phytophthora spp. using these two fungicides . Gray et al. recently reported the Fluopicolide and oxathiapiprolin EC50 values for several Phytophthora species associated with citrus on California. Fluopicolide EC50 values for P. citrophthora, P. syringae, P. nicotianae, and P. hibernalis ranged from 0.031 to 0.087, 0.02 to 0.0461, 0.039 to 0.095, and 0.017 to 0.018 µg/ml, respectively. Of the four fungicides evaluated in this study, oxathiapiprolin had the lowest EC50 values . This range is similar to EC50 values reported for other Phytophthora spp. including P. sojae, another member of the phylogenetic clade 7, which includes P. cinnamomi . In agreement to our study, Gray et al. , also found that this fungicide had the lowest EC50 values among five different fungicides tested. The authors reported oxathiapiprolin EC50 values for P. citrophthora, P. syringae, P. nicotianae, and P. hibernalis ranged from 0.0002 to 0.0015, 0.0002 to 0.0003, 0.0003 to 0.001, and < 0.0003 µg/ml, respectively. Interestingly, in contrast to potassium phosphite sensitivity, the Southern isolates in this study exhibited lower EC50 values than the Northern A2 clade I isolates. These results suggest the potential to rotate oxathiapiprolin with phosphonates and mefenoxam for controlling avocado PRR in California reducing the risk of the emergence of phosphonate-resistant P. cinnamomi isolates. Significant variation in pathogenicity and virulence among P. cinnamomi isolates collected from different host plants have been previously reported . Few cases have reported no differences in virulence among P. cinnamomi isolates collected from different hosts and unique host including one study in avocado . In this study we found significant differences in virulence among three representative P. cinnamomi isolates from the two A2 clonal groups identified by Paglaccia et al. when we inoculated a moderate resistant avocado rootstock but not the most susceptible one. The use of highly susceptible plants to distinguish between isolates with different levels of virulence is challenging and could explain why we did not detect significant differences in virulence among our isolates when we used a susceptible avocado rootstock . Although the mixture of the A2 clade II isolates were more virulent than the mixture of the A2 clade I isolates , we observed that the mixture of all the isolates together exhibited the same disease severity as the mixture of the less aggressive ones . This observation might be explained by the level of competition between these two groups of might reflect the induction of specific plant defense responses triggered by these two distinct groups of isolates, a more comprehensive study is required to test these two possibilities.

Subsequently, the biochemical data from both V7-berries and V9-berries were correlated to the WGCNA modules, and only 2 modules, M21 and M30, displayed substantial correlations with berry polyphenols, containing 5349 and 4559 genes, respectively . The M21 module was positively linked with TAC , but negatively associated with tannins, catechin, and quercetin glycosides . On the contrary, the M30 module exhibited a positive correlation with tannins, catechin, and quercetin glycosides , but was negatively linked with TAC . The DEGs obtained from the two pipelines were assigned to both M21 and M30, yielding 604 and 1362 genes, respectively . Interestingly, the number of DEGs in each module, M21 and M30, was roughly equal to the down- and upregulated genes, respectively . To identify flavonoids/tannins-related genes that might result in such astringency diversity between V7-berries and V9-berries, hub genes were searched in the DEGs list of both modules . Only 8 hub genes were identified based on their transcript abundances in V9- berries and predicted functions. However, based on our previous work , 30 litre plant pots we found another 11 genes that are significantly expressed but with a log2FoldChange less than 1.5, and they were included in our further analysis .

The enrichment analysis of GO showed considerable enrichment in the BP GO terms for secondary metabolite biosynthetic process , flavonoid biosynthetic/metabolic process , L-phenylalanine metabolic/ catabolic process , phenylpropanoid metabolic process , phenylpropanoid biosynthetic process , chorismate biosynthetic/metabolic process , cinnamic acid biosynthetic/ metabolic process , anthocyanincontaining compound biosynthetic/metabolic process . The KEGG pathway analysis confirmed the BP GO terms, exhibiting enrichment for the biosynthesis of secondary metabolites , phenylpropanoid biosynthesis , flavonoid biosynthesis , and glutathione metabolism .To precisely elucidate their significance in the tannins/astringency diversity between V7-berries and V9-berries, we studied the expression levels of the 19 hub genes associated with the shikimic and flavonoids pathway. Except for the PAL1_1 gene , the analysis of their relative expression by real-time quantitative PCR showed a significant correlation with the Transcripts Per Million values for genes of interest, validating the transcriptomic data from both V7- and V9-berries . In general, all genes showed higher expression levels in V9-berries compared to V7-berries, but with different degrees of induction. Forinstance, the two genes involved in the shikimic acid pathway, chorismate synthase , and chorismate mutase , showed visibly higher accumulation abundance in V9-berries at the third harvesting time with approximately 6-fold and 3-fold increases, respectively, compared to V7-berries.

Similarly, the upstream structural genes in the phenylpropanoids pathway, including phenylalanine ammonia lyase , trans-4- coumarate biosynthesis , and 4-coumaroyl:CoAligase 2 , were significantly induced by approximately 2- to 9-fold in V9-berries. Regarding flavonoids/PAs biosynthesis, chalcone synthase is considered a key enzyme in this pathway, converting p-coumaroyl-CoA to naringenin chalcone, which is later turned into naringenin by chalcone isomerase . Both genes were highly expressed in V9-berries . Naringenin is subsequently converted by flavonoid 3’-monooxygenase to dihydromyricetin and dihydroquercetin, which are further transformed by dihydroflavonol 4-reductase into leucodelphinidin and leucocyanidin, respectively . The expression levels of F3H and DFR also showed a commensurate induction with the upstream genes in V9-berries relative to V7-berries. Subsequently, leucoanthocyanidin dioxygenase and leucoanthocyanidin reductase catalyse the conversion of leucodelphinidin to delphinidin and -gallocatechin, respectively, as well as leucocyanidin to cyanidin and catechin, respectively. These three genes also exhibited a significant increase in V9-berries. Finally, the expression of genes encoding glutathione Stransferases , one of the most essential anthocyanin transporters, was significantly higher in V9-berries compared to V7-berries, with approximately 3- to 9.2-fold changes .

Our data showed that the expression of flavonoids/PAs related-genes was highly increased in V9-berries at the third harvest time compared to V7- berries, resulting in the accumulation of more PAs in V9-berries.Developing and producing table grapes with high quality is of utmost importance for the success of grapevine breeding programs. Scarlet Royal table grape , variety , is one such success story, producing premium fruit quality and becoming one of the major red varieties in California. However, under certain unknown circumstances, the berry quality of Scarlet Royal grapes can be affected by undesirable astringent taste, which can negatively impact marketability and consumer acceptance. Research on the relationship between astringency and phenolic composition in table grapes is still scarce, especially on the transcriptomic level. In this study, we aimed to understand the molecular events involved in the development of berry astringency, which is a complex set of sensations resulting from the shrinking, drying, drawing, or puckering of the mouth epithelium . We focused on Scarlet Royal berries from two different vineyards with contrasting astringency and analyzed the changes in phenolic-related compounds at six different time points from veraison until the last harvesting time. Our panel test revealed that the V9-berries were perceived as more astringent, a characteristic that could be attributed to their elevated levels of tannins . Differences observed between the two vineyards under study indicate that V7 vines yield more compared to V9. This difference may be attributed to the lower cluster count in V9, a factor known to potentially contribute to astringency, as suggested by Cañon et al., 2014 in wine grapes. Additionally, petiole analysis revealed higher levels of nitrogen and potassium in V9 vines compared to V7. Vine nutrient levels contribute to the final berry quality at harvest . These factors may also contribute to the higher levels of tannins detected in V9 berries; however, further research is needed to confirm this theory. It’s worth noting that weather conditions can play a role in inducing astringency. Nevertheless, the two vineyards are located in close proximity to each other, and weather data collected from the same station in the Delano area indicates similar conditions. Therefore, it is unlikely that astringency or higher phenolic compounds are induced by weather factors. In fact, several studies, mainly in wine, have pointed to PAs as a determining factor for astringency intensity . For example, Vidal et al. reported that the total amount of tannins is the most plausible factor for sensory astringency, with flavan-3-ols dimers, trimers, and non-galloylated tetramers contributing to the astringency sensation. The PAs are a group of oligomers and polymers of flavan-3-ols and are the naturally occurring and predominant type of tannins in grapes and wine . Another study on aronia berry juice confirmed PAs as the key astringent compounds using sensory evaluation and phenolic profile approaches along with in-vitro models . The study found that PAs with higher degrees of polymerization were responsible for the strong astringent mouthfeel . The composition of phenolic substances, especially PAs, 25 liter pot plastic seems to play a crucial role in determining berry astringency, and further exploration of this relationship is warranted in fresh fruits of different species and cultivars. Understanding the molecular basis of astringency development in Scarlet Royal berries can provide valuable insights for improving grape breeding programs and enhancing the overall quality of table grapes.The relationship between astringency and the berry polyphenols content has not been explored yet in table grape at the molecular level. To the best of our knowledge, the present study provides the first transcriptome profiling along with the changes of polyphenols in grape berries of the same variety but having astringency diversity .

The transcriptome profile of both V7-berries and V9-berries underlined the remarkable transcriptional shift during berry ripening at different vineyards . Commonly, berry transcriptome profiles may widely vary based on many factors, including genotypic variations among varieties/species and developmental stages , as well as environmental circumstances. In our case of study, stemmed differences from the developmental stages and genotypic variations were eliminated, andhence the difference of the vineyard locations was the main source of variance with 97% of variance . The identified DEGs output of V9-berries compared to V7-berries is highly explanatory, including polyphenolic-related genes that are robustly expressed and co-regulated with astringency development, particularly in the V9-berries. The enrichment of the up-regulated genes with BP GO terms related to the biosynthesis of secondary metabolites, phenylpropanoid, and nitrogen compound metabolic process , commensurate with the higher amounts of N found in V9- berries . In fact, not only the levels of N fertilization but also its different forms highly affected the composition of phenolic compounds in leaves and wine . However, the synergistic/antagonistic effects of other macro- and micro-nutrients should also be considered. Our results highlighted the negative impact of above-normal amounts of macronutrients, mainly N, and to a lesser extent P and K, on the desirable attributes of grape berries. Otherwise, the positive effect of Ca, Mg, and Mn were achieved as their levels were maintained within the normal range . These data should be also seen in the light of the highly enriched BP GO terms in the down regulated genes . Particularly, those for hormonal signaling pathways such as auxin, abscisic acid, strigolactones, as well as the KEGG pathway for the carotenoid biosynthetic pathway .The transcriptome profiling identified the common and unique molecular events featuring the development of tannins/astringency in grape berries. It is well-documented that the synthesis of PAs in grapevines is achieved via three sequential pathways: the shikimate pathway, the phenylpropanoid pathway, and ultimately the flavonoid pathway . Our results revealed that the expression levels of flavonoids/PAs-related genes were highly induced in V9- berries at the third harvesting time compared to V7-berries. The 19 selected genes were involved in the three pathways: the shikimate pathway, phenylpropanoids pathway, and flavonoids pathway. The shikimate pathway is an alternative route to produce aromatic compounds, including phenylalanine, tyrosine, and tryptophan, which serve as precursors for various metabolites, such as phenolic compounds . The up-regulation of genes like chorismate synthase and chorismate mutase in V9-berries may lead to the accumulation of phenylalanine, which is a critical precursor for the phenylpropanoid pathway. The latter pathway is responsible for synthesizing several end products, including PAs, anthocyanins, lignin, lignans, hydroxycinnamic acid esters, and hydroxycinnamic acid amides . Under the conditions of the V9 vineyard, several PAs/flavonoids structural genes such as PAL, C4H, 4CL, CHS, CHI, F3H, LDOX, LAR, and ANR were induced in V9-berries, leading to the accumulation of PAs in the berries . This process is facilitated by GSTs and transported by multidrug and toxic compound extrusion transporters. The activation of the PAs biosynthetic pathway in V9- berries may lead to a reduction in the necessary substrates for anthocyanin synthesis, resulting in low red color intensity in V9- berries compared to V7-berries. Additionally, the accumulation of PAs is associated with the development of astringency taste in V9-berries. Our study provides valuable insights into the molecular events underlying astringency development in Scarlet Royal berries. By integrating transcriptome profiling with polyphenolic composition analysis, the research shed light on the co-regulation of genes involved in the shikimate, phenylpropanoid, and flavonoid pathways, leading to the synthesis of PAs and ultimately influencing astringency. The findings from this research have implications for grapevine breeding programs and the production of high-quality table grapes. Understanding the molecular mechanisms underlying astringency development can help breeders in selecting and developing grape varieties with desirable attributes. Additionally, the knowledge gained from this study can inform vineyard management practices, such as nutrient fertilization, to optimize polyphenolic composition and berry quality. In conclusion, the data presented in this study indicates that berry astringency is strongly correlated with a high tannin content, likely resulting from the activation of nineteen genes within the phenylpropanoid pathway. The activation of these genes shifts the flavonoid biosynthesis pathway towards proanthocyanins, leading to increased tannin accumulation in the berries. It appears that triggering these events is associated with nutritional imbalances and a lower number of clusters per vine, as confirmed by petiole nutrient levels and the observed lower berry soluble solids and higher titratable acidity levels. The identification of these genes holds significant value for table grape genetic improvement programs. The nutrient imbalance theory derived from this research could be applied worldwide to optimize grapevine fertilization programs. Furthermore, it paves the way for further research in this area, with a particular focus on vine nutrients, crop load management, and berry astringency, thereby contributing to advancements in the field of table grape cultivation.The names of the repository/repositories and accession number can be found in the article/Supplementary Material.The cultivated garden strawberry , an allo-octoploid , has a unique natural and domestication history, originating as an interspecific hybrid between wild octoploid progenitor species approximately 300 years before present.

New migrants’ short United States experience translates into a less-developed network to assist their mobility and employment. As a result, they hold the worst and lowest-paid jobs, and are usually the last to be hired and the first to be fired as the peak harvest seasons run their course. In Santa Maria’s strawberry harvest, for instance, they typically occupy the crest of the high employment season and move on to other production sites before the season is completely over. Many find daily employment with a variety of employers but only to fill momentary gaps, to aid short-handed crews, or to meet special urgent contracts. Most, in effect, secure employment through farm-labor contractors. New migrants, in contrast with traditional migrants, are much more mobile and versatile. They travel up and down the California geography, and in and out of Oregon and Washington, following a variety of crops. Some chase the berry harvest, starting on the Mexican border in February and ending up in the state of Washington by mid-June, always striving to remain on the crest of the peak harvest season when piece-rate earnings are at their best. Others become involved in other highly seasonal crops such as cherries, asparagus, 30 plant pot pickle cucumbers, raisin grapes, oranges, and apples which are spread out throughout both the west coast geography and the agricultural calendar.

In the Santa Maria Valley, new migrants are especially present during the peak strawberry season, April-June, and again in September to participate in the short but intense wine-grape harvest. Since most new migrants come from highly impoverished rural regions of Mexico, they travel in large family groups without children or other unemployable dependents who could slow them down or hinder full employment during the course of their trek. It is not uncommon for these families to leave children and other dependents behind in shanty towns and camps located on the Mexican side of the border while the most productive and employable members seek jobs and wages in the United States. Many of the interviewed new migrants enter California in February and return to their home communities in southern Mexico by mid-November. During their stay in the Santa Maria Valley they typically crowd into local hotels and small unfurnished apartments. In 1991 and 1993 we observed as many as eight workers sharing a double hotel room and up to sixteen individuals jammed into a small one-bedroom apartment. The incidence of undocumented workers among both traditional and new migrants is quite high. Data collected in 1993 reveals that as many as fifty to sixty percent of traditional migrants are undocumented. Moreover, those who do possess appropriate authorization to work in the United States only received it recently through IRCA’s SAW program. In contrast, only ten to fifteen percent of the new immigrants are documented.

All, nonetheless, hold some sort of paperwork which is required to obtain employment. The high incidence of unauthorized/undocumented workers, compounded with the fact that many actually hold counterfeit documents, makes migrants into a population that resists enumeration and identification, a circumstance that is further complicated by migrants’ easy mobility and unconventional housing arrangements. Finally, with respect to census-taking efforts, it is important to emphasize that there are few migrants in the Santa Maria Valley by April 1. At that time, the vast majority of migrants are either just starting off on their annual treks from their home communities in Mexico or are busy harvesting strawberries in other southern producing areas such as Baja California, northern San Diego County, and the Oxnard- Ventura plain where the fruit matures earlier. As indicated above, the thick of the migrant presence in Santa Maria does not occur until strawberries reach their peak in mid-to-late April. Approximately one thousand individuals who form part of Santa Maria’s sizable agricultural labor force maintain a permanent home base in the U.S.-Mexico border area, either in small colonias in or near El Centro, Calexico, and Yuma or in Mexico itself, especially in or near the city of Mexicali. From these communities they regularly commute to the Santa Maria Valley where they participate in the lettuce harvest which extends from spring to fall. Most of the border area commuters are employed by a few large corporations that have come to monopolize the lettuce industry by, among other means, maintaining production sites in different parts of the state: in Santa Maria and other coastal valleys in the summer and in Imperial Valley in the winter.

Some of these companies regularly transport farm equipment, vacuum cooling plants, and office facilities over great distances, from summer to winter producing sites and back. Large lettuce producers have also developed a highly specialized and stable labor force that travels from site to site as needed. These are the lechugueros or specialized lettuce harvesters , who maintain a permanent home base in the border area, near winter production sites, from where they migrate seasonally to summer production sites such as the Santa Maria Valley. Lechugueros explain that in the border area they find affordable housing, lower cost of living, and a more favorable sociocultural environment. Few of them are originally from the border itself but after the Bracero Program was cancelled settled there as an ideal location from which to access U.S. employment. Many of them can be traced back to the traditional sending communities of Central Mexico. Professional lechugueros are a breed apart among California’s agricultural laborers in that they enjoy nearly year-round employment, always with the same employer, by following the crop from production site to production site. They also earn relatively high wages, $1,200 to $1,500 monthly with some benefits. At home on the border and during the winter months, while lechugueros are busy with the winter harvest, other family members also find part-time, intermittent employment in local agricultural endeavors. During the summer, however, only lechugueros migrate to the distant production sites, leaving behind dependents and other family members who, nonetheless, continue to seek part-time occasional farm jobs near home. Migrants return home occasionally, every two or three weeks, for a few days to visit family and friends, and to rest. During their stay in the Santa Maria Valley, lechugueros rent apartments which they share with other commuters to cut down expenses. A few experienced commuters have installed small, grow raspberries in a pot dilapidated trailers in the area which they use as a temporary second home. Most of the lechugueros we interviewed in 1991 and 1993 are documented and have been so for some time. A few who do not possess either “green cards” or citizenship use commuter border passes issued to them years ago by INS which entitle them to work in the United States while living on the Mexican side of the border. Those who, before 1986, lacked adequate documentation were subsequently able to legalize by accessing IRCA’s SAW program with the encouragement, sponsorship, and assistance of their employers. Because lechugueros, relatively speaking, lead fairly conventional lives, they are much less apprehensive about being identified and counted and, as a result, offer little resistance to census takers and other surveyors. Nonetheless, those who maintain a permanent home base on the Mexican side of the border are likely to be missed during the census count, while those who live on the U.S. side risk being counted twice owing to the circumstance that in the early spring they typically occupy two homes. Above we have described and categorized the bulk of the work force employed by Santa Maria Valley agriculture. The four types of workers we have described thus far have established some degree of routine or recurrent behavior over the past years according to opportunities created by their farm jobs and/or specific arrangements they have made with the larger family group to which they belong. The four described categories account for approximately eighty-five percent of the farm workers employed by Santa Maria farms during the course of a complete agricultural cycle. There is, in addition, an undetermined number of single unattached workers, mostly young males, who spontaneously show up in the valley during peak employment seasons and who remain there only as long as employment is available; otherwise they quickly move on to other work locations. Although it is difficult to ascertain the exact number of these transients, we estimate there is a constant pool of 300 to 500 such workers in the Santa Maria Valley at any given time.

Overall, up to two or three thousand individuals may pass through Santa Maria during the course of the year; some remain in the valley only for a few days while others may stay there for several months. Interviews conducted in 1991 and 1993 reveal that some of these workers follow a preconceived itinerary designed to land short-term jobs in especially demanding crops through a network of farm labor contractors . Indeed, a few of the interviewed transients were originally recruited by farm-labor contractors in the border area and in their home communities deep in Mexico to perform a specific job in California and, once completed, they were referred to other labor contractors in other work locations. Most, however, are on their own and seek out farm-labor contractors upon arriving at a new location to inquire for work and shelter. Single unattached transients land the worst possible jobs and receive rock-bottom wages, often at rates below the minimum wage. They are usually employed as day laborers and they rarely know for how long or for how much. In a good week a transient worker can yield as much as $200 but typically monthly earnings rarely exceed $400. They, moreover, experience long and frequent periods of unemployment between jobs. Despite their erratic and transient lives, these workers continue to be strongly attached to their families in their home communities in Mexico to whom they send part of their wages whenever they can spare them. Many, in effect, aspire to return home before Christmas with presents, new clothes, and $1,000 cash in the pocket. It is, however, not uncommon for transients to remain in the U.S. for several consecutive seasons, only to return home when they are broke, homesick, and/or ill. As would be expected, few transient workers are documented but most have acquired fake documents. While in Santa Maria, transients find shelter either in one of the few labor camps still open, or in garages, tool sheds, shacks and trailers offered by their employers at a price. Many camp out in the fields, in boxcars, or in their cars. Only when the weather forces them will they choose to stay in one of the local hotels that caters to migrant farm workers. They are, as a result, the most difficult workers to track down, find, interview, and enumerate. We came across them, almost fortuitously, when we examined and interviewed members of strawberry, wine grape, and celery harvest crews. In this report we have described the forces that attract immigrant and migrant farm workers from Mexico to the Santa Maria Valley , and we have described a variety of forms and behaviors of that immigrant and migrant labor force. Moreover, in the process we have identified some of the circumstances that hinder an accurate accounting of this population. In this section, we draw upon the information we have gathered in order to propose strategies to improve the identification, description, and enumeration of immigrant and migrant farm workers in California. One unassailable conclusion derived from our field research in the Santa Maria Valley is that a considerable number of immigrant and migrant farm workers prefer not to be identified and, hence, will actively avoid and frustrate efforts designed to enumerate them. They will, moreover, often provide erroneous, false, and incomplete information when they are pressed by surveyors. Some farm workers are reluctant to cooperate because they do not possess appropriate authorization to be and to work in the United States; others, although authorized, resist to protect family members and friends who are not; and many, although they have nothing to hide, have a deeply imbedded mistrust of any official government effort to identify, describe, and enumerate them. Many have at one time or another lived and worked illegally in the United States, have experienced apprehension, deportation, and harassment, and hence maintain a cautious, suspicious attitude towards all government officials, especially those who want to know more about them. Active resistance to identification and description compounds the well-known difficulties encountered in attempts to enumerate immigrant and migrant farm workers due to, among other circumstances, their frequent mobility, their unconventional housing arrangements, and language barriers.

The transfer and extension of ideas and concepts in order to bring new topics under the compass of existing theory has obvious scientific merit . It also has pitfalls. The failings of early “evolutionist” models of social evolution and their archaeological adaptations, as well as social Darwinist interpretations, are well-rehearsed subjects in anthropology. Contemporary anxieties about the use of neo-Darwinian theory in anthropology are more narrowly and analytically focused, and sometimes not so easy to set aside. A recent example would be debate over the claim by Rindos that his co-evolutionary account of plant domestication had successfully banished human intent from an explanatory role in this process . In the present volume we take for granted the relevance to agricultural origins of neoDarwinian and behavioral ecology theory. We reject without explicit argument the sub-stantivist claim of economic anthropology that none of the tools of formalist, microeconomics has any purchase outside of modern capitalist economies . To the contrary, we believe it evident that the basic concepts of HBE are fundamental to the analysis of any economy. Close attention to their use in HBE we believe will stimulate new applications and models specifically designed to analyze mixed economies and food production. We are more receptive to the argument that specific foraging models, developed as they were for foragers, may be only partially appropriate to the analysis of emergent food producers. For instance, raspberry plant container the diet breadth model assumes random encounter with resources, a condition increasingly likely to be violated as foragers become involved in the manipulation of individual species.

In as much as all models simplify reality and thus violate at least some conditions of their application, the unavoidable judgment is this: does the failure to fit this particular assumption completely vitiate the heuristic or analytical value of the model? With the specific cautions cited in individual papers, we believe the combined weight of the case studies developed in this volume add up to a strong presumption in favor of the utility of foraging theory, even as the foragers being analyzed direct more and more of their effort toward agricultural activities. We envision three levels where HBE might be applied to the question of agricultural origins. Extant models, although designed for the analysis of foraging, might be applied in the analysis of agricultural origins with little or no alteration in their structure and assumptions. This is the procedure of most authors in this volume. Extant models might be modified so to more directly address questions or situations specific to non-foraging aspects of economy, including cultivation and agricultural production. The modification of central place foraging models to analyze the question of field processing is an especially good example of this. Finally, entirely new models, inspired directly by the problem of explaining human subsistence transitions, might be devised using fundamental behavioral ecology concepts such as opportunity cost or discounting. We think of these options as adopt, adapt, or invent, respectively.

While options and hold great potential for novel and perhaps quite interesting analyses, it appears from the papers assembled here that there is much to be accomplished with the simple adoption of existing models.The fresh market berry industry in Santa Cruz and Monterey counties is an excellent example of transformation in the business of agriculture over the last 50 years. Located along the Central Coast of California, the two counties span the fertile Pajaro and Salinas valleys, and are well known for their amenable climate and production conditions, their diverse crop mix and grower demographics, and their developed agricultural infrastructure and support industries. The majority of the berry sector is comprised of strawberries , raspberries and blackberries , with blueberries and other miscellaneous berries produced on a much more limited basis. Substantial research-based literature and historical information is available for Central Coast strawberries; however, despite the area’s move towards greater production of raspberries and blackberries, less information exists for these crops. We seek here to provide a more complete portrayal and historical context for the berry industry in the Santa Cruz and Monterey area, which is the origin of the berry industry in California. While the berry industry has been very successful in recent decades, it now faces new challenges, such as invasive pests and the phaseout of the soil fumigant methyl bromide. This article draws on previous and more recent research to discuss some of the influences that have contributed to the berry industry’s dramatic expansion in Santa Cruz and Monterey counties, including selected innovations in agricultural practices and heightened consumer demand. During the 1960s and 1970s, the number of acres planted to berries, tons produced and value of production fluctuated. The fluctuations can be partly explained by farm management: in the past growers often rotated berry and vegetable crops to assist with soil and pest management, thereby influencing these statistics. However, annual crop reports from the county agricultural commissioners show that since the 1980s, berries have become increasingly important to each county’s overall value of production, and by 2014 accounted for 64% and 17% of the total value of all agricultural products in Santa Cruz and Monterey counties, respectively .

The industry’s growth can be explained by a shift of some acreage out of tree fruits and field crops , among others, into berries, and by additional acreage put into agricultural production. Strawberries are the undisputed leader in the berry sector and in 2014 represented 58% and 94% of the value of all berry production in Santa Cruz and Monterey counties, respectively , and 50% and 93% of all berry acreage . Table 2 documents the remarkable expansion of the strawberry industry over time in both counties with respect to acreage, tons produced and value of production. Between 1960 and 2014, acreage more than tripled and production increased tenfold. The value of production, in real dollars, increased by 424% in Monterey County and by 593% in Santa Cruz County, reaching an astonishing combined value of nearly $1 billion in both 2010 and 2014. The gains in all statistical categories in Monterey County were enabled in part by an expansion of production into the southern reaches of the county where more and larger blocks of farmland are available, container raspberries and where land rents are lower than in Santa Cruz and northern Monterey counties. However, from 2010 to 2014 Monterey County’s tonnage and production values declined, possibly because the area has recently experienced a shortage of labor to harvest fresh market crops. Tonnage was also lower in Santa Cruz County, but production values increased. This may be because of the county’s greater emphasis on local agriculture, organic production and direct market sales, which are often associated with higher crop values. For raspberries, the acreage, tons produced and value of production grew steadily and most strikingly in Santa Cruz County , where production conditions for caneberries are optimal. For example, caneberry fields in Santa Cruz County are situated in areas that have well-drained soils and are protected from damaging winds. Also, fields are planted to take advantage of the growth and yield gains associated with southern exposures. Moreover, field-to-cooler travel distances are shorter in Santa Cruz County, which is critical for safeguarding the quality and marketability of these highly perishable crops. By 2014, raspberries represented 33% of the county’s total value of production for all berries. In contrast, Monterey County raspberry production accounted for only 6% of the county’s total berry value. Blackberries have not been consistently reported as a separate category in archived statistical analyses, but instead were often included under the terms “bush- or miscellaneous berries”. Therefore, similar data for blackberry acreage and value of production cannot be reported here. However, between 1990 and 2010, Santa Cruz County agricultural commissioner crop reports reported an upward trend for the broad category with respect to acreage planted and value of production . In 2010, blackberries were promoted to a position of prominence in the report and shown as a separate statistic; at the same time, the miscellaneous berry category was shown to be very small indeed. Between 2010 and 2014, however, blackberry acreage and value of production leveled off and have shown only modest gains . This may be because there has been less emphasis on production and market research and promotion for blackberries than for strawberries or raspberries. No comparable data are available for Monterey County. The two counties have contributed significantly to California’s total berry sector: in 2014, area strawberry acreage represented 35% of the statewide total, 37% of the total tons produced and 38% of the total value of production . Area raspberry acreage represented 43% of the statewide total, 42% of the total tons produced and 39% of the total value of production. Comparable statewide statistics are not available for blackberries. County agricultural commissioners’ reports show that the majority of all berries produced in the two counties — up to 98% — are sold as fresh market fruit . In years with adverse production conditions or low prices, a higher percentage of the crop may be diverted to the freezer or processed products market. Fresh market fruit is handled and sold primarily through local grower-shippers; a much smaller share is sold directly to consumers through farmers markets, community supported agriculture operations, farm stands and other direct and intermediated market channels such as restaurants, independent grocers and schools.

Arguably the most momentous shift in cultural practices for strawberries was the introduction of preplant soil fumigants, beginning with chloropicrin in the 1950s and methyl bromide in the 1960s. Fumigation is a soil disinfestation practice that improves plant productivity and helps with the management of arthropods, nematodes, weeds, soilborne fungi and other plant pathogens. Some of the most difficult to control pathogens include Verticillium dahliae, Fusarium spp. and Macrophomina phaesolina. Without soil fumigation, these pathogens have the potential to completely destroy strawberry plantings. Early on, when CP and MB were mixed and applied together, the synergistic effects allowed strawberries to be produced as an annual rather than a biennial crop, and to be grown continuously on the same land without rotation to another crop, resulting in an increase in annual strawberry acreage. The use of fumigants also led to higher and more predictable yields and fruit quality, and further enabled the development of more stable markets for strawberries . Yields for strawberries statewide increased from a range of 2 to 4 tons per acre prior to the introduction of soil fumigants to 16 tons per acre by 1969 . Additional cultural improvements included the development of both UC and proprietary strawberry varieties uniquely adapted to coastal production conditions. Varieties were bred, for example, for disease resistance, yield and market potential. Notable UC-bred strawberry varieties include Tufts , Pajaro, Douglas, Chandler, and Selva , Camarosa and Seascape , and Aromas, Albion and Monterey . Irrigation practices also evolved, shifting from furrow irrigation in the 1960s to drip irrigation in the 1980s, which led to further improvements in plant disease management and greater water use efficiency. These and other enhancements meant that by 2012, yields could exceed 35 tons per acre . More recently, the strawberry industry has focused on “fine-tuning” fertility and water management for more efficient resource use, along with additional yield and fruit quality improvements . The Santa Cruz–Monterey area is also recognized for its early experience with conversion of conventional strawberry production to organic management . Organic strawberry production was shown to result in lower yields, which, when offset by premium prices could potentially offer higher net returns to growers. The importance of crop rotation for disease management was not addressed in the initial study by Gliessman et al. but has since been the focus of additional research, as have more complete analyses of the economics of organic strawberry production . Growers and area researchers continue to collaborate and advance organic strawberry production techniques. Most notably, a long-term research commitment has been made to determine organically acceptable disease management practices such as anaerobic soil disinfestation , the use of commercially available soil-applied biological organisms and the incorporation of soil amendments such as mustard seed and its derivatives. The area is now seen as a global leader in organic strawberry research, and in 2012 the first organic strawberry production manual was published by UC Agriculture and Natural Resources . Statistics documenting expansion of the organic strawberry industry over time are not available on a county-by-county basis, but statistics for California show prodigious growth in acreage and value of production: from $9.7 million in 2000 to $93.6 million in 2012, a 621% increase in real dollars .

Similarly, a comparison of herbivory damage on herbarium specimens of non-native plants in urban versus rural environments might provide insights into one pathway towards species invasion. Many non-native plant species are introduced into urban areas, and urbanization may provide warm, enemy-free space where they can establish and subsequently expand. Though the role of urbanization in natural enemy release and subsequent invasions is not well characterized, we might predict that non-native plants escape their natural enemies in urban areas and experience increased herbivory rates when they move into natural areas where they encounter a higher diversity of herbivores.Responses to global change, such as those in space and time, discussed above, encompass plasticity in behaviour or physiology and distributional shifts, which may be rapid. However, there is growing evidence that evolutionary responses might also be rapid, assuming there is sufficient standing genetic variation for selection to act upon. While fluctuating selection can maintain this standing variation, providing the raw material for future adaptive responses, strong directional selection, such as that imposed by anthropogenic climate warming, plastic gardening pots can erode genetic variation and potentially impede evolutionary adaptation, elevating population extinction risk.

Insect herbivores and the plants they feed upon are locked in an evolutionary arms race, and insect herbivory drives contemporary plant evolution, changing plant allele frequencies within a few generations. It is likely that climate-induced shifts in herbivory will impose additional selection on both plants and insect herbivores already under pressure from direct effects of climate change. Natural history collections that span multiple generations can provide a record of evolutionary changes and constraints. It can be difficult, however, to disentangle plastic and evolutionary responses. Evolutionary responses can be predicted from the breeder’s equation, but this requires extensive long-term population data. For species that can be stored in a dormant state, such as plants, it is possible to contrast ancestral and descendent genotypes grown under common conditions, and Franks et al. were able to demonstrate evolution to earlier flowering in Brassica using stored seeds. Seedbanks and other collections that hold propagules, intentionally or incidentally, could thus provide important data for exploring evolutionary responses and testing whether species might be approaching limits in their adaptive responses. Sequencing of archived tissue of plants and animals already allows for the signature of selection to be sought directly in their DNA. New collections could systematically sample seeds through time or across populations, providing the potential to resurrect past populations and examine micro-evolutionary change.

Evolutionary insights from herbarium specimens might be particularly useful for adapting agricultural practices with global change. Alongside the insights that collections data can provide on ecological and impacts of global change in natural systems, herbaria are additionally repositories of crop wild relatives . CWR are important sources of phenotypic and genetic information on pest and disease resistance that may be introgressed into crops. For example, comparative analyses of CWR might provide an opportunity to identify herbivore-resistance traits relevant to agricultural and ornamental species, such as glandular trichomes that act as physical defences against insects and can be detected on herbarium specimens with a microscope. Herbaria provide a record of this genetic diversity even when it is no longer present in the wild. In addition, herbivore damage on CWR herbarium specimens might help predict increases in pest pressure on crops, because closely related host species tend to be vulnerable to similar suites of pests and pathogens. Specimens in herbaria can also serve as records of past biotic threats and inform how we can avoid these threats in the future. For example, Yoshida et al. sequenced the genomes of Phytophthora infestans, the cause of potato late blight, infamous for its role in the Irish Potato Famine, from herbarium collections of infected potatoes and tomatoes.

Using genomic tools, they found one strain of P. infestans linked to the potato blight in the nineteenth century, but that multiple strains moved globally in the twentieth century. In a recent study, we quantified historical insect damage on a crop species, the low bush blueberry, Vaccinium angustifolium, growing in the wild to determine how pest pressure has changed with recent climate change. The low bush blueberry is an ecologically and economically important endemic species in northeastern North America, whose production has seen recent increases owing to awareness of the health benefits of blueberries. Collection records from the Harvard University Herbaria suggest that herbivore damage has increased in recent years, with evidence that increased herbivory is a result of winter climate warming. This highlights the need for increased monitoring of herbivore species on V. angustifolium and allows the development of proactive pest management practices that could be implemented before economic impacts are felt.Given the millions of plants and insect specimens that are becoming available online, it will increasingly be possible to assess changes in phenological synchrony, distributions, and occurrence over time across diverse taxa and large spatial areas. The sampling of species within museums and herbaria, however, is non-random and often sparse, which can present distinct challenges depending on the response variable of interest and how robust the data are for answering particular questions. However, the depth of sampling within natural history collections is difficult to assess because natural history collections data are often dark—without searchable databases—despite efforts to rapidly digitize. Another obstacle is that data associated with museum specimens can have large uncertainty; for example, specimens collected before the advent of geographical information system technology often have only coarse scale location data that may prohibit local-scale analyses. When assessing phenological change, the most important challenges arise because of biases in collecting. Herbarium specimens are more likely to be collected near roads; rare species are, perhaps unsurprisingly, collected less frequently, and collections are more likely to be made in spring or summer months. Such biases can make specimen data difficult to work with. For example, roads might be warmer than the surrounding countryside, and observations of shifts in phenology through time might, in part, also reflect the increasing extent of the road network. Finally, sampling frequency may bias estimates of first events, because we are more likely to observe earlier events with greater sampling intensity. Such sampling biases can make it difficult to compare across species when sampling effort varies, for example, between common and rare species. New methods offer a solution to such challenges. For example, methods have been established for calibrating species distribution models according to known biases in presence-only data, and newly constructed statistical models allow robust estimates of the tail of a distribution—in the context of phenology, first flower, for example—even when sampling is uneven. Shifting collection practices may also introduce biases. Herbivory measurements derived from herbarium specimens are probably underestimates in most cases because collectors try to avoid collecting damaged specimens. Even so, herbivory is prevalent on specimens and matches patterns derived from theory and observations from living plants. Importantly, biases introduced by collectors are not necessarily problematic if they do not vary across axes of interest. For example, if collectors are equally likely to collect relatively undamaged specimens across latitude, blueberry pot size herbarium specimens might still provide insights into how herbivory varies with latitude. When there are concerns that collecting practices may have influenced observations—for example, perhaps collectors are more or less likely to collect damaged specimens over time—collector identity may be added to statistical models to partially control for such biases. A unique challenge to using herbarium specimens is that they are eaten by a suite of insects within museums. This loss of material can reduce the use of insect specimens for morphological and genetic analyses. For plants, chewing herbivory created indoors, after a plant was collected, can be confused with damage created while plants were alive. We developed protocols that allowed us to reliably discriminate chewing damage created pre- and post- collection described in.

Such approaches, however, require careful examination of specimens with a microscope and entomological knowledge to recognize diagnostic features of damage to plants, which is a barrier to large scale, rapid scoring of chewing damage on digitized specimens. Other types of insect damage, such as leaf mines, skeletonization and galls, are almost never a product of insects eating plants within museums, and might be scored more reliably, although their prevalence is lower.We have previously argued that herbaria should be repositioned as hubs for ecological research, and we provided suggestions for how to manage collections to promote ecological research on global change. Because the vast majority of research in collections has historically been on taxonomy and systematics, collections are rarely faced with providing data for ecologists and evolutionary biologists. Stronger relationships between researchers in the field, collections managers, and digital data providers would help ecologists to better address the challenging ecological questions of global change, and, importantly, could also increase funding opportunities for maintaining and building natural history collections, which are often under-funded and threatened by institutional priorities. Here, we provide three suggestions for how natural history collections and ecologists can work together to support global change research on species interactions. First, it would be helpful to detail the sampling protocol used to collect specimens. In many cases, collecting practices are haphazard, but if, for example, a curator collects a specimen expressly to document a gall, this would change the inferences we can make from this specimen . Second, ecologists could engage with curators in projects that involve resampling areas and taxa that have long historical records, ideally at the same time of year and with the same research effort involved in previous collections. Third, specimens are most useful when researchers can associate collections with important predictor variables representing species traits or abiotic data related to global change. New opportunities exist to link specimens to the published literature and trait databases , BIEN as well as non-traditional data sources, such as written records and historical photographs. The better integration of new bio-informatics tools and digital databases within biological collections will help transition museums and herbaria into ecological data centres.The volume before you is the first systematic, comparative attempt to use the concepts and models of behavioral ecology to address the evolutionary transition from societies relying predominantly on hunting and gathering to those dependent on food production through plant cultivation, animal husbandry, and the use of domesticated species embedded in systems of agriculture. Human behavioral ecology is not new to prehistoric analysis; there is a two-decade tradition of applying models and concepts from HBE to research on prehistoric hunter-gatherer societies . Behavioral ecology models also have been applied in the study of adaptation among agricultural and pastoral populations. We review below a small literature on the use of these models to think generally about the transition from foraging to farming, while the papers collected here expand on these efforts by taking up the theory in the context of ethnographic or archaeological case studies from eleven sites around the globe.There are older transformations of comparable magnitude in hominid history; bipedalism, encephalization, early stone tool manufacture, and the origins of language come to mind . The evolution of food production is on a par with these, and somewhat more accessible because it occurred in near prehistory, the last eight thousand to thirteen thousand years; agriculture also is inescapable for its immense impact on the human and non-human worlds . Most problems of population and environmental degradation are rooted in agricultural origins. The future of humankind depends on making the agricultural “revolution” sustainable by preserving cultigen diversity and mitigating the environmental impacts of farming. Simple population densities tell much of the story. Huntergatherers live at roughly 0.1/km2 ; rice agriculturists in Java at 1,000/km2 , a ten-thousand-fold difference. There were an estimated ten million humans in the world on the eve of food production ; now oversix billion people live on this planet, an increase of 600% in only ten millennia. Agriculture is the precursor, arguably the necessary precursor, for the development of widespread social stratification, state-level societies, market economies, and industrial production . Social theory maintains that present-day notions of property, equality and inequality, human relationships to nature, etc., are shaped, at least in part, by the social organization, technology, or food surpluses entailed in our dependence on agriculture.

Random effects were modeled with plant identity nested within site to account for the block design of the experiment and to control for variation between our sites. To model count data and to correct for over dispersion, we used a Poisson-lognormal model with a log link function by including a per-observation random effect as described above .We modeled CBB removal by ants using a GLMM. We included treatment , coffee plant distance to nest tree, ant activity on coffee plants after string placement, the interaction between treatment and distance, and the interaction between treatment and ant activity on plants as fixed effects . Random effects were modeled with plant identity nested within site to account for the block design of the experiment and to control for variation between our sites. To model count data in our response variable we used a Poisson distribution with a log link function.We constrained model selection to include biologically pertinent terms for inference and to aid in model interpretation. A full model of these terms was tested, along with subsequent models of different covariate combinations and a null intercept-only model of random effects . The best fit model was determined via backwards model selection compared to the full model, blackberries in containers where the model that resulted in the lowest AIC score with ∆AIC > +2 was selected. Overall significance in models was assessed using Wald type II Chisquared tests. Statistical differences among treatments were compared by Wald Z tests .

In all cases, fixed effect parameters and the variance of random effects was estimated by maximum likelihood with Laplace approximation using the ‘glmer’ function in the ‘lme4’ package in R . To aid in data interpretation, we removed one coffee plant replicate from our analysis where measured ant activity was more than double that of any other plant measured and may have resulted from an unusually high buildup of scale insects which are tended by A. sericeasur on coffee. Additionally, one nest tree replicate was not included in the tree activity analysis because the data were not collected at that site. Finally, coffee plant height and distance to nest tree were centered and scaled to aid model interpretation. All analyses were performed in R .Our experiment demonstrates that the addition of string to connect shade trees and coffee plants in coffee agroecosystems facilitates movement for A. sericeasur and potentially increases ant recruitment rates. Studies in natural systems have reported increases in ant activity with arboreal connections across the arboreal stratum , possibly driven by the easy access these pathways provide to resources . Other ants, such as Pogonomyrmex spp. prefer linear arboreal substrates and switch to cleared routes as a mechanism to reduce the energetic costs of ant foraging , and in some cases to decrease the risk of encountering predators . The observed increase in ant activity on connected coffee plants after the placement of strings suggests that structural connectivity can increase ant recruitment rates to foraging areas in coffee and may enhance the efficiency of movement for A. sericeasur.

This may lead to increased foraging efficiency for ants and enhanced resource capture rates on coffee. However, this could also reflect other benefits associated with using linear arboreal substrates, such as avoiding predators, a behavior that is known to occur in A. sericeasur . Using more efficient foraging pathways and thereby avoiding the leaf litter as a primary foraging substrate may potentially protect A. sericeasur workers from the attack of the phorid fly parasitoid Pseudacteon spp. . While ant activity only significantly increased after string placement on connected coffee plants, we also observed lesser increases in ant activity on control coffee plants and nest trees . This unexpected result could mean that strings, a novel element in the environment, acted as a form of habitat modification or disturbance, which increased overall ant activity in the local area. However, if our manipulation were the cause, we would have expected the ants to attack the jute strings , a behavior that we did not observe during the experiment. Experiments in tropical forests have shown that the long-term removal of lianas can influence ant richness on trees , and therefore may possibly also affect overall ant abundance and activity when promoted. It is also possible that other factors could potentially explain this result in control plants, such as changes in local abiotic factors that we did not measure systematically in our experiment. Future research which expands on the temporal scope of this study may be useful in assessing the long-term effects of artificial connectivity in this system. Ant activity post string placement was negatively affected by distance to the nesting tree .

This result is consistent with previous studies suggesting that within 5 meters A. sericeasur dominance in the leaf litter decreases with distance to the nesting tree . However, in our study, the effect of distance after string placement was significant only on control plants, but not on connected plants. This suggests that connections could buffer the negative effects that larger distances from the nesting tree pose to ant activity and potentially increase ant-provided biological control services in these plants. Connected coffee plants also had significantly higher CBB removal than control plants . Overall, greater ant activity on coffee plants was associated with higher CBB removal rates , suggesting that ant activity directly influenced CBB removal rates. However, while this effect was significant on control coffee plants it was only marginally significant on connected plants. While we believe that these results support the hypothesis that connectivity enhances ant foraging and bio-control services on coffee, the use of dead CBB in this experiment as a proxy to measure bio-control may explain the only marginally significant effect of ant activity on CBB removal in connected plants. It is possible that dead prey exhibit more variable recruitment responses from ants than live prey. Despite this, it is likely that strings facilitated ant movement to coffee plants by providing a smooth, linear substrate and indirectly increased CBB removal . In other systems, the leaf-cutting ant Atta cephalotes uses fallen branches to rapidly move between areas and thereby quickly discover new food resources . Similarly, these resources allow scouts to return quickly to the colony, minimizing the time taken for information transfer and recruitment of other foraging workers . The role of trunk trails and fallen branches has received extensive attention in the leaf-cutting ant system, however, fewer studies have looked at the influence of connectivity resources on foraging behavior of predatory arboreal ants. Surprisingly, CBB removal did not follow the same trend as ant activity with distance to the nesting tree. While control plants tended to have lower CBB removal rates than connected plants as distance to the tree increased, blackberry containers we did not find a significant effect of distance on CBB removal in either control or connected plant groups. Collectively, these results suggest that connections in the arboreal stratum have the potential to increase ant activity and therefore enhance plant protection from CBB attack, particularly in connected plants. Further studies should assess the effect of distance on CBB removal using plants located at distances larger than 3.5 m from the tree. It is important to note the potential for negative impacts of enhanced ant activity on coffee plants resulting from hemipteran tending behavior. While ant activity can increase the density of green coffee scale insects, which may harm coffee plants and reduce coffee productivity, the scale are not a major pest in the region of study, and are not as economically significant as the coffee berry borer . A recent study evaluating the benefits associated with the indirect Azteca–Coffea mutualism, which emerges from the Azteca-scale mutualism, found that the protective benefit ants provide to coffee plants is positively associated with high densities of the scale . Therefore, it is possible that enhanced CBB control associated with scale-tending by ants outweighs the costs associated with scale damage. However, these interactions may be context-dependent, and still need to be fully evaluated in the field to provide a holistic understanding of the impact of connectivity on scale density and coffee yield. Other ant species could also benefit from the addition of connections between coffee plants and shade trees, such as Cephalotes basalis and Pseudomyrmex simplex, which were observed using these connections during our study.

The ant P. simplex has been previously reported as an important CBB bio-control agent, acting in conjunction with other species of ants to effectively suppress CBB at various life stages . Therefore, this technique could support Azteca ants as well as other ant species that play an important role in suppressing CBB populations. Our results support the general hypothesis that connectivity, one measure of habitat complexity, can sustain important ecological processes in natural and managed ecosystems. In aquatic systems, more complex habitats with macrophytes allow for greater food capture and maintain higher levels of diversity . In terrestrial systems, higher complexity can influence trophic dynamics . In coffee agroecosystems, ants are highly sensitive to habitat change and management intensification, generally expressed as the reduction of shade, elimination of epiphytes, and use of chemical inputs . Such intensification can have a negative effect not only on vegetation connectivity and ant foraging, but may also cascade to affect ecosystem services, such as biological control. Our study supports the idea that promoting complexity at a local scale, in this case providing structural resources for ants in agroecosystems, can significantly enhance connectivity within the arboreal strata, and potentially improve biological control of coffee pests. This idea has already been successfully implemented in other agricultural systems, placing “ant bridges” made of bamboo strips or strings connecting neighboring trees in , and could be incorporated as a management strategy in coffee systems. Future research should evaluate the practical feasibility of adding connections between vegetation strata to enhance bio-control. For example,studies in timber plantations have estimated that the presence of ants increases timber production by 40%, and that ants can be maintained at lower costs by providing intra-colony host tree connections using rope, poles or lianas . It is important that future studies in coffee also consider the costs of other CBB control methods, such as the application of the pesticide endosulfan, which can lead to the development of resistance, can negatively impact natural enemies, and can have harmful impacts on human health . Further investigation into promoting ant bio-control with artificial connections in coffee should: 1) assess economic tradeoffs, management applicability, and farmers’ perceptions of this method in large and small coffee plantations, 2) compare the cost between string placement and other management approaches , and 3) assess coffee yields on connected and not connected plants to provide management recommendations. More broadly, incorporating conservation bio-control strategies in combination with vegetation connectivity is consistent with criteria identified as key for the sustainability of biological control, such as increasing local habitat quality and enhancing species’ dispersal ability . Generally, the maintenance of shade trees and natural vegetation in agroforestry systems may increase vegetation complexity and natural connectivity between plants to promote ant foraging and subsequent biological pest control. The extent to which biotic and abiotic factors shape species interactions and their distributions has been a central focus for community ecologists . Included in the wide spectrum of factors shaping community dynamics are the diversity and availability of food resources and habitat complexity; all are important determinants of species diversity, distribution and interactions . Recent theoretical advances and empirical work in community ecology suggest that further research is needed to understand how resource availability and environmental factors shape species interactions. Specifically, one research gap is in our understanding of how variation in resources along habitat complexity gradients affects species interactions . However, empirically demonstrating how resources vary and how species respond is methodologically complicated, in the sense that the manipulation of multiple resources and consumers is not always straight forward, especially in complex systems. Consequently, studies have focused primarily on one single resource and– disproportionately– on competitive species interactions. Further, the environmental context in which resources matter is also not well understood and will gain more importance as natural and managed systems continue to experience habitat simplification .

Pleasant esters in red wines include ethyl acetate which has a OAV threshold of 12264 µg•L-1 and is described as fruity and balsamic , as well as isoamyl acetate, described as banana aroma with a OAV threshold of 30 µg•L-1 . In 2020, ethyl acetate was reduced in C0 and D5 wines, shading and reduced cluster temperatures preserved isoamyl acetate aromas in D1, D3 and D5 wines. When compared to wines from 2021, cooler vintage conditions did not result in ester compositional changes in exposed and shaded wines. Similarly, fatty acid esters were preserved in shaded wines, while 2020 C0 wines consistently had the lowest concentration of all measured fatty acid ethyl esters and various esters, all of which are associated with fruity and candy-like aromas. Concentrations of ethyl octanoate and ethyl decanoate remained beneath the reported perception threshold, thus observed shifts in composition with shading may be undetectable in Cabernet Sauvignon wines. However, ethyl hexanoate and ethyl isovalerate have remarkably low OAV thresholds of 5 µg•L-1 and 1 µg•L-1 , respectively . In the present study, all wines were above these thresholds, indicating that reductions in fruitiness may be perceived. This overall decrease in fruity aromas with cluster exposure and excess temperatures may negatively impact the marketability of Cabernet Sauvignon wines from hot viticulture regions with increasingly more frequent heat wave events associated with climate change.

Unpleasant and rancid aromas include isobutyric acid which imparts a cheese aroma and benzaldehyde which is associated with almond aroma in red wines . In this study, growing raspberries in container isobutyric acid concentrations were only affected in 2020, with D4 having the highest isobutyric acid concentration. The detection threshold for this aroma compound is 2300µg•L-1 . Concentrations detected in the experimental wines were substantially below this threshold, indicating that this slight increase in rancid aromas in D4 wines may not negatively impact overall wine perception. Given that D4 wines also exhibited enhanced fruitiness in with improved ester composition, the trade-off of slight increases in rancid aromas may be offset by the net benefit from increased fruity aromas in the wine aroma profile. While terpenes are often critical in white wines, these compounds when present in red wines have a large effect on wine aromas as their OAV thresholds are relatively low . The OAV threshold for a-terpinene, cis-rose-oxide and linalool are 250 µg•L-1 , 0.2 µg•L-1 and 25.2 µg•L-1 , respectively . The In 2020, α-terpinene, cis-rose-oxide and linalool were all reduced in C0 wines compared D4 and D5 wines, however concentrations of these compounds did not exceed the OAV threshold. These compounds produce odors such as peach, citrus, rose, and floral aromas in red wines . Previous work indicated an increase in terpenoids, particularly linalool in wines produced from fruit under black and red shade nets .

It was demonstrated that heat treatment will down regulate genes encoding key enzymes in terpenoid metabolism in Cabernet Sauvignon grapevines . Thus, increases in terpenoid content in shade film wines in 2020 may be due to reduced cluster temperature in a growing season with frequent heat wave events. In 2021, C0 wines exhibited the highest concentration α-terpinene, while cis-rose-oxide concentrations remained low in C0, and linalool was unaffected. In 2021, a cooler growing season with fewer days above 38°C may have resulted in less variation in terpenoid composition and net accumulation of terpenoids in exposed fruit . Ultimately, climatic shifts towards more frequent heat wave events will reduce floral and citrus aromas in wines produced from overexposed clusters. However, the year-to-year weather variation will enhance the unpredictability of the development of these compounds, leading to challenges for wine producers looking to produce a consistent product. As carotenoid breakdown products, C-13 norisoprenoids like β-damascenone often described by sweet and floral aromas and has an OAV threshold of 0.05 µg•L-1 . C-13 norisoprenoids have been shown to have a positive linear relationship with sunlight exposure to the grape cluster . Under extreme light intensity and temperature conditions, there are decreases in carotenoid concentration in the berry, thus reducing C-13 norisoprenoid precursors. In the present study, β- damascenone was highest in C0, D4 and D5 wines in 2020, while β-damascenone was highest in C0 and D1 wines in 2021, contrary to previous findings in hot viticultural areas. Lee et al. reported that grape clusters without leaf removal and inner canopy clusters contained more β- damascenone than south-facing clusters exposed to solar radiation by leaf removal. Likewise, black cloth and red shade net enhanced β-damascenone concentration compared to uncovered control .

Despite varied reports, Lee et al. also demonstrated a linear positive relationship between norisoprenoids in the grape berry and concentrations in wine, with the berry concentration was always greater than that of the resultant wines. It may be possible that carotenoid degradation due to excessive temperatures in C0 treatments was negligible or less than the biosynthesis of C-13 norisoprenoids, resulting in similar concentrations as D4 and D5 shade film treatments. Therefore, the results of this study demonstrated that partial solar radiation exclusion with reductions in UVA, UVB and NIR radiation does not hinder norisoprenoid content in wines. Additionally, the concentrations of β- damascenone across all treatments in both years exceeded the odor active threshold for this compound, indicating that significant differences in β-damascenone concentrations between C0 and treatments may be perceivable in resultant wines.Although grapevine is one of the most resilient crops globally, the changing climate is one of the many challenges to its cultivation and ultimately wine production. According to the Intergovernmental Panel on Climate Change , global air temperatures are likely to increase 1.5-4.5o C between 2030 and 2052 . Historical records of growing degree day accumulation demonstrate that air temperatures in the world’s most notable grape growing regions have increased steadily within the last 70 years . Such increases in GDD accumulation disrupt the natural coupling and balance of primary and secondary metabolites during ripening, corresponding with a plateau in wine quality ratings . Subsequently, excessive air temperatures reduce pleasant and desirable wine aroma compounds, but also contribute to reductions in wine quality . Moreover, predicted changes in precipitation patterns and increased drought frequency threaten grapevine water status conducive to market-desired fruit yield and composition and long-term vineyard sustainability. With increasingly frequent and prolonged drought periods and less predictable rainfall, vineyards will need to adapt to changes in water availability. The evaluation and performance of drought tolerant root stock and scion cultivars has also been investigated ; however, their adoption may be limited due to historical and cultural connections to popular grape cultivars. Additionally, the effect of root stock-scion interactions on water use efficiency is poorly understood and only recently became an area of research . At the field scale, large plastic pots for plants wider row spacing to decrease vine density can decrease overall vineyard evapotranspiration by reducing the competition for water between vertically shoot-positioned vines . Pieri et al. examined the water balance of two planting densities in five viticultural regions of France and concluded that lower planting densities utilizing constrained canopies can maintain vine water status within moderate stress levels in forecasted climate change conditions. However, decreased plant density may result in lower yields at the field-scale, requiring an economic cost/benefit analysis to determine its viability as a water conserving solution. Reducing applied water through sustained and regulated deficit irrigation strategies is already commonly used to improve flavonoid composition in the grape skins . Furthermore, varied amounts of applied water have been trialed in a hot growing region such as California and demonstrated that irrigating at 50% of potential grapevine evapotranspiration was sufficient to mitigate water shortages when dormant season precipitation was limited . More deliberate interventions to adapt to heat and water shortages in the vineyard include the use of shade cloths and films to reduce canopy temperatures and vine evapotranspiration . Again however, the implementation of these shade structures is under question as they present barriers to vineyard mechanization and may be a costly and unfeasible long-term solution.

Adapting trellis systems may be another method for mitigation of climate change impacts in production vineyards. Choosing an appropriate trellis system is an important pre-planting decision during vineyard establishment. An appropriate trellis system optimizes the vine’s capacity to intercept solar radiation and produce a canopy microclimate that results in optimal berry ripening without excessive direct solar radiation overexposure to the fruit zone. A traditional and commonly used trellis system in various grapevine production areas worldwide is the vertically shoot positioned trellis. While VSP trellises were traditionally thought to improve berry ripening, the VSP trellis system maximizes light penetration and canopy porosity, producing a canopy microclimate which increases cluster vulnerability to overexposure in hot viticulture regions . More recent work has investigated the resiliency of red wine grapes in hot viticulture regions when training systems are varied from the traditional VSP trellis. In a study conducted in Napa Valley CA, USA, trellis systems with free and sprawling canopies such as a single-high wire and high-quadrilateral systems increased yield and produced berries with improved flavonoid profiles that are attributed to reduction in chemical degradation compared to traditional VSP trellis systems regardless of applied water amounts . Additionally, the interactive effect of varied applied water amounts and trellis systems has been minimally investigated. Williams and Heymann applied various fractions of estimated potential grapevine evapotranspiration to VSP and Scott-Henry trellis systems to elucidate the effect of applied water on vine productivity and fruit composition in Livermore, CA. In their study, irrigation amounts had a larger effect on vine productivity and berry quality than trellis systems due to VSP and Scott-Henry trellis systems having similar levels of overexposure to the fruit zone . Free and sprawling trellis systems which can shade the fruit zone and protect it from overexposure conditions can provide a long-term feasible heat avoidance strategy for hot viticulture regions due to promoting larger canopies. While there are demonstrated improvements to grape chemical composition with the adoption of these sprawling trellis systems, it is understood that trellis systems promoting larger leaf area indices will have a higher water demands . In regions where irrigation is required to supplement seasonal precipitation, maintaining these larger canopies may prove difficult, especially with increasingly stringent environmental regulations such as the Sustainable Groundwater Management Act in the state of California. SGMA limits groundwater extraction for agricultural irrigation . Compliance with SGMA will result in allotted water use restrictions in California’s Napa Valley, limiting growers to 120 mm of applied water each season. Therefore, there is uncertainty surrounding how growers will respond to such water restrictions in tandem with adapting to increasing temperatures in a climate change scenario. Ultimately, there is a lack of information on the water footprint of resilient trellis systems hindering their adoption in microirrigated wine grape production vineyard. Our previous works conducted with VSP trellis indicated that irrigating at different percent of potential grapevine ET affected grapevine physiology leading to different carbon allocation, water footprint, and water use efficiency in hot climates . Likewise, our previous work provided evidence that trellis systems other than VSPs provide better adaptation of wine grapes to climate change by ameliorating physiological performance and berry chemistry due their canopy architecture . Therefore, the objective of this experiment was to determine the water use efficiency of grapevine with trellis and pruning types that are commonly used in production regions characterized by hot climates. We hypothesized that the new trellises that were indicated to be more resilient to climate change would have different water needs than traditional VSP. Therefore, we applied fractions of the potential grapevine evapotranspiration estimated for VSP to different trellis systems to compare their water productivity relative to VSP under a climate change scenario.Climate change in hot viticultural regions brings two prominent challenges: higher air temperatures with unpredictable heat wave events and increased drought frequency . At the experimental site in Oakville, CA, the 2021 growing season was cooler than both the preceding and following growing seasons. Hot air temperatures may create untoward growing conditions that affect whole grapevine physiology . In hot viticultural regions like California, prolonged drought conditions are becoming more common and increasingly severe. In the current study, extreme and exceptional drought conditions were recorded across the three experimental years. Total precipitation at the experimental site during the water year within the last decade was previously reported as approximately 768mm . The total precipitation recorded during the 2019-2020 and 2020-2021 growing seasons was 234.2mm and 278.3mm, respectively and was substantially less than the long-term average.

This aspect could have an important influence in the eligibility characteristics such as polyphenol composition. In fact, the content of polyphenols in grapes is clearly affected by four agro-ecological factors: the cultivar, the year of production , the site of production , and the degree of maturation. Moreover, the methods of vinification and applied technological procedures can significantly modify both the concentration and composition of polyphenols and, therefore, also the color intensity and hue of red wines. The increasing of yield and vine vigor can also affect the color, polyphenol composition, and sensory attributes of Cabernet Sauvignon wines. In conclusion, Sangiovese wines from Italy and California showed several significant chemical differences in term of eligible and identity profiles , such as polyphenols composition and volatiles that not completely affected the intrinsic sensory quality. Concerning the perceived quality, despite the Tuscan experts perceived differences between the Californian and Italian wines, they considered them similar when they evaluated their typicality. Finally, the results from this study confirm that perceived quality in terms of typicality of Sangiovese was still related not only to fruity and floral flavors but also to lightness and freshness, plastic pots for planting despite the intrinsic quality aspect of the “structure” of the wine and to what is considered a “good” color.

Moreover, the findings confirm that Sangiovese shows a flexibility in terms of chemical and sensory modification, according to the production area and that it can be considered typical even if it comes from an area far away from the traditional ones. Agriculture is a key human activity in terms of food production, economic importance and impact on the global carbon cycle. As the human population heads toward 9 billion or beyond by 2050, there is an acute need to balance agricultural output with its impact on the environment, especially in terms of greenhouse gas production. An evolving set of tools, approaches and metrics are being employed under the term “climate smart agriculture” to help—from small and industrial scale growers to local and national policy setters—develop techniques at all levels and find solutions that strike that production-environment balance and promote various ecosystem services. California epitomizes the agriculture-climate challenge, as well as its opportunities. As the United States’ largest agricultural producing state agriculture also accounted for approximately 8% of California’s greenhouse gas emissions statewide for the period 2000–2013. At the same time, California is at the forefront of innovative approaches to CSA. Given the state’s Mediterranean climate, part of an integrated CSA strategy will likely include perennial crops, such as winegrapes, that have a high market value and store C long term in woody biomass. Economically, wine production and retail represents an important contribution to California’s economy, generating $61.5 billion in annual economic impact.

In terms of land use, 230,000 ha in California are managed for wine production, with 4.2 million tons of winegrapes harvested annually with an approximate $3.2 billion farm gate value. This high level of production has come with some environmental costs, however, with degradation of native habitats, impacts to wildlife, and over abstraction of water resources . Although many economic and environmental impacts of wine production systems are actively being quantified, and while there is increasing scientific interest in the carbon footprint of vineyard management activities, efforts to quantify C capture and storage in annual and perennial biomass remain less well-examined. Studies from Mediterranean climates have focused mostly on C cycle processes in annual agroecosystems or natural systems. Related studies have investigated sources of GHGs, on-site energy balance, water use and potential impacts of climate change on productivity and the distribution of grape production. The perennial nature and extent of vineyard agroecosystems have brought increasing interest from growers and the public sector to reduce the GHG footprint associated with wine production. The ongoing development of carbon accounting protocols within the international wine industry reflects the increased attention that industry and consumers are putting on GHG emissions and offsets. In principle, an easy-to-use, wine industry specific, GHG protocol would measure the carbon footprints of winery and vineyard operations of all sizes. However, such footprint assessment protocols remain poorly parameterized, especially those requiring time-consuming empirical methods.

Data collected from the field, such as vine biomass, cover crop biomass, and soil carbon storage capacity are difficult to obtain and remain sparse, and thus limit the further development of carbon accounting in the wine sector. Simple yet accurate methods are needed to allow vineyard managers to measure C stocks in situ and thereby better parameterize carbon accounting protocols. Not only would removing this data bottleneck encourage broader participation in such activities, it would also provide a reliable means to reward climate smart agriculture.Building on research that has used empirical data to compare soil and above ground C stocks in vineyards and adjacent oak woodlands in California, this study sought to estimate the C composition of a vine, including the relative contributions of its component parts . By identifying the allometric relationships among trunk diameter, plant height, and other vine dimensions, growers could utilize a reliable mechanism for translating vine architecture and biomass into C estimates . In both natural and agricultural ecosystems, several studies have been performed using allometric equations in order to estimate above ground biomass to assess potential for C sequestration. For example, functional relationships between the ground-measured Lorey’s height and above ground biomass were derived from allometric equations in forests throughout the tropic. Similarly, functional relationships have been found in tropical agriculture for above ground, below ground, and field margin biomass and C. In the vineyard setting, however, horticultural intervention and annual pruning constrain the size and shape of vines making existing allometric relationships less meaningful, though it is likely that simple physical measurements could readily estimate above ground biomass. To date, most studies on C sequestration in vineyards have been focused on soil C as sinks and some attempts to quantify biomass C stocks have been carried out in both agricultural and natural systems. In vineyards, studies in California in the late 1990s have reported net primary productivity or total biomass values between 550 g C m−2 and 1100 g C m−2. In terms of spatial distribution, some data of standing biomass collected by Kroodsma et al. from companies that remove trees and vines in California yielded values of 1.0–1.3 Mg C ha−1  year−1 woody C for nuts and stone fruit species, and 0.2–0.4 Mg C ha−1  year−1 for vineyards. It has been reported that mature California orchard crops allocate, on average, one third of their NPP to the harvested portion and mature vines 35–50% of the current year’s production to grape clusters. Pruning weight has also been quantified by two direct measurements which estimated 2.5 Mg of pruned biomass per ha for both almonds and vineyards. The incorporation of trees or shrubs in agroforestry systems can increase the amount of carbon sequestered compared to a monoculture field of crop plants or pasture. Additional forest planting would be needed to offset current net annual loss of above ground C, representing an opportunity for viticulture to incorporate the surrounding woodlands into the system. A study assessing C storage in California vineyards found that on average, drainage for plants in pots surrounding forested wildlands had 12 times more above ground woody C than vineyards and even the largest vines had only about one-fourth of the woody biomass per ha of the adjacent wooded wildlands.The objectives of this study were to: measure standing vine biomass and calculate C stocks in Cabernet Sauvignon vines by field sampling the major biomass fractions ; calculate C fractions in berry clusters to assess C mass that could be returned to the vineyard from the winery in the form of rachis and pomace; determine proportion of perennially sequestered and annually produced C stocks using easy to measure physical vine properties ; and develop allometric relationships to provide growers and land managers with a method to rapidly assess vineyard C stocks.

Lastly, we validate block level estimates of C with volumetric measurements of vine biomass generated during vineyard removal.The study site is located in southern Sacramento County, California, USA , and the vineyard is part of a property annexed into a seasonal floodplain restoration program, which has since removed the levee preventing seasonal flooding. The ensuing vineyard removal allowed destructive sampling for biomass measurements and subsequent C quantification. The vineyard is considered part of the Cosumnes River appellation within the Lodi American Viticultural Area, a region characterized by its Mediterranean climate— cool wet winters and warm dry summers—and by nearby Sacramento-San Joaquin Delta breezes that moderate peak summer temperatures compared to areas north and south of this location. The study site is characterized by a mean summer maximum air temperature of 32 °C, has an annual average precipitation of 90 mm, typically all received as rain from November to April. During summer time, the daily high air temperatures average 24 °C, and daily lows average 10 °C. Winter temperatures range from an average low 5 °C to average high 15 °C. Total heating degree days for the site are approximately 3420 and the frost-free season is approximately 360 days annually. Similar to other vineyards in the Lodi region, the site is situated on an extensive alluvial terrace landform formed by Sierra Nevada out wash with a San Joaquin Series soil . This soil-landform relationship is extensive, covering approximately 160,000 ha across the eastern Central Valley and it is used extensively for winegrape production. The dominant soil texture is clay loam with some sandy clay loam sectors; mean soil C content, based on three characteristic grab samples processed by the UC Davis Analytical Lab, in the upper 8 cm was 1.35% and in the lower 8–15 cm was 1.1% . The vineyard plot consisted of 7.5 ha of Cabernet Sauvignon vines, planted in 1996 at a density of 1631 plants ha−1 with flood irrigation during spring and summer seasons. The vines were trained using a quadrilateral trellis system with two parallel cordons and a modified Double Geneva Curtain structure attached to T-posts . Atypically, these vines were not grafted to rootstock, which is used often in the region to modify vigor or limit disease .In Sept.–Oct. of 2011, above ground biomass was measured from 72 vines. The vineyard was divided equally in twelve randomly assigned blocks, and six individual vines from each block were processed into major biomass categories of leaf, fruit, cane and trunk plus cordon . Grape berry clusters were collected in buckets, with fruit separated and weighed fresh in the field. Leaves and canes were collected separately in burlap sacks, and the trunks and cordons were tagged. Biomass was transported off site to partially air dry on wire racks and then fully dried in large ventilated ovens. Plant tissues were dried at 60 °C for 48 h and then ground to pass through a 250 μm mesh sieve using a Thomas Wiley® Mini-Mill . Total C in plant tissues was analyzed using a PDZ Europa ANCA-GSL elemental analyzer at the UC Davis Stable Isotope Facility. For cluster and berry C estimations, grape clusters were randomly selected from all repetitions. Berries were removed from cluster rachis. While the berries were frozen, the seeds and skins were separated from the fruit flesh or “pulp”, and combined with the juice . The rachis, skins and seeds were dried in oven and weighed. The pulp was separated from the juice + pulp with vacuum filtration using a pre-weighed Q2 filter paper . The largest portion of grape juice soluble solids are sugars. Sugars were measured at 25% using a Refractometer PAL-1 . The C content of sugar was calculated at 42% using the formula of sucrose. Below ground biomass was measured by pneumatically excavating the root system with compressed air applied at 0.7 Mpa for three of the 12 sampling blocks, exposing two vines each in 8 m3 pits. The soil was prewetted prior to excavation to facilitate removal and minimize root damage. A root restricting duripan, common in this soil, provided an effective rooting depth of about 40 cm at this site with only 5–10 fine and small roots able to penetrate below this depth in each plot. Roots were washed, cut into smaller segments and separated into four size classes , oven-dried at 60 °C for 48 h and weighed. Larger roots were left in the oven for 4 days.

Meta-analysis of cohort studies has identified increased risk in obese individuals =1.89, 95% confidence interval : 1.51–2.36 for developing liver cancer compared to normal weight individual while meta-analysis of prospective studies correlated a larger waist circumference and waist–hip ratio with increased risk for colon cancer. Similarly, diabetics are more than twice as likely to be diagnosed with cancer of the liver, pancreas, endometrium, and to a lesser extent, colon, breast, and bladder.5 Many possible underlying mechanisms including hyperinsulinemia, hyperglycemia, and inflammation have been proposed to explain the increased cancer incidence. Insulin, produced by b-cells in the pancreas, is released to promote cellular absorption of blood glucose and many factors including excess weight and increased plasma triglyceride levels can raise circulating levels of insulin. Chronic insulin elevation results in resistance, which then increases the biological activity of insulin-like growth factor , an endocrine and paracrine hormone regulating tissue growth and metabolism. Epidemiological studies have linked IGF-1 to several cancer types, including hepatocellular carcinoma and colorectal cancer . Moreover, excess adiposity leads to the derangement of other peptide hormones such as resistin, leptin, adiponectin, pot with drainge holes and tumor necrosis factor α , contributing to the metabolic abnormalities commonly observed in obese and diabetic individuals.

Indeed, increased leptin and reduced adiponectin have been identified as risk factors for the progression of liver steatosis, fibrosis, and tumorigenesis as well as CRC formation. Both bile acids and the intestinal microbiota have been extensively studied in the context of various health conditions, particularly obesity and type II diabetes-associated HCC and CRC. Although the exact mechanism of how gut microbes and BAs affect one another remains unclear, it is evident that the introduction of intestinal microbes increased liver cholesterol and altered BA profiles in germ-free mice. Conversely, dietary BA supplementation can modulate gut microbial profile in animal models.This review will focus on the current understanding of the complex interplay between BAhomeostasis and gut microbial profiles in regards to obesity and diabetes-associated liver and colon carcinogenesis. They are synthesized by cholesterol catabolism in the liver through both the classical and the acidic pathway , which differ in the modification order of the sterol ring and side chain oxidation. BAs synthesized in the liver are subsequently conjugated for storage in the gallbladder.

Upon ingestion of fat and protein, cholecystokinin, a peptide hormone in the small intestine will stimulate the release of bile containing digestive enzymes and primary BAs, cholic acid and chenodeoxycholic acid , from the gall bladder. These BAs will then activate farnesoid x receptor in the liver which induces the expression of small heterodimer partner to inhibit the activity of liver receptor homolog-1 responsible for upregulating the rate-limiting BA synthesis enzyme CYP7A. Intestinal FXR activity on the other hand, induces the expression of fibroblast growth factor 19 which binds hepatic fibroblast growth factor receptor 4 and activates c-Jun N-terminal kinase 1/2 and extracellular signal-regulated kinase 1/2 to inhibit BA synthesis. BAs are actively reabsorbed from the ileum by the ileal BA transporters and circulated back to the liver through the hepatic portal vein. This highly efficient process ensures that a majority of synthesized BAs are recycled with only 1-2% being converted into secondary BAs, deoxycholic acid , and lithocholic acid , by bacterial 7α-dehydroxylation in the terminal ileum and colon and excreted in feces. The regulation of BA circulation between the liver and intestines is summarized in Figure 1. In addition to modulating BA synthesis, FXR also regulates the expression of several transporters including apical sodium dependent BA transporter , fatty acidbinding protein subclass 6, and organic solute transporter α and β to control the absorption of not only BAs but also lipids, vitamins, and xenobiotics. Interestingly, recent studies have implicated FXR in the interplay between obesity-associated BA dysregulation and gut dysbiosis to potentially promote carcinogenesis in the liver and colon. Within the context of obesity and diabetes, FXR can regulate glucose and lipid homeostasis through actions at various sites along the gut-liver axis.

Agonist activation or hepatic overexpression of FXR significantly lowered blood glucose levels in both diabetic and wild type mice. FXR stimulation also decreased blood low density lipoprotein levels and inhibited fatty acid and TG synthesis in mice fed a high sugar and fat diet. These combined effects of FXR protected mice against body weight gain, liver and muscle fat deposition, and reversed insulin resistance. At the metabolic level, FXR functions to repress hepatic gluconeogenesis, lipogenesis, and fatty acid synthesis genes. Consequently, FXR stimulation promotes glycogen synthesis and enhances insulin sensitivity in obese mice. FXR activity in pancreatic β-cell lines and human islets can regulate transcription factor Kruppellike factor 11 to increase insulin gene expression and protein kinase B-dependent phosphorylation and translocation of glucose transporter 2 at the plasma membrane of hepatocytes. By stimulating pancreatic insulin secretion and hepatic glucose uptake, FXR can effectively delay the pathological progression of insulin resistance, hyperglycemia, and glucosuria in diabetic mice. Consistently, FXR knockout mice exhibited glucose intolerance, insulin insensitivity, elevated serum TG, cholesterol, and BA levels resulting in greater hepatic fat accumulation compared to wild type mice. Hepatic FXR expression is conversely regulated by glucose levels in streptozotocininduced diabetic rats. Chromatin immunoprecipitation in mice also revealed that long-term high-glucose exposure increased histone acetylation and demethylation on the FXR-target Cyp7a1 gene promoter region leading to elevated basal expression and consequently, a larger BA pool with altered composition. These observations strongly support the existence of crosstalk between the cellular mechanisms regulating glucose, lipid, and BA homeostasis in the liver and intestines with FXR serving mediator. A link between FXR and enterohepatic cancer was firmly established when FXR KO mice were found to have markedly elevated hepatic inflammatory and oxidative stress markers compared to WT mice and a striking 100% incidence rate of spontaneous liver tumors between 13 and 15 months of age. BA-containing diet further exacerbated inflammation and oxidative stress in FXR KO mouse liver supporting that BA dysregulation subjects hepatocytes to higher oxidative stress. Hepatocyte-specific over expression of SHP failed to alter liver tumor incidence or size in FXR KO mice, large pot with drainage but did result in lower neoplasia grade, decreased cell proliferation, and increased apoptosis. Moreover, FXR stimulation can down-regulate lipopolysaccharide -induced, nuclear factor kappa-light-chainenhancer of activated B cells -mediated hepatic inflammation by suppressing the expression of proinflammatory mediators in human HCC cells and mouse primary hepatocytes. FXR KO mice displayed higher hepatic mRNA levels of inducible nitric oxide synthase, prostaglandin-endoperoxide synthase 2 , chemokine ligand 10, and interferon type II which resulted in exaggerated inflammation and necrosis after LPS exposure at a dose that failed to elicit measurable liver injury or inflammation in WT mice. The HCC in FXR KO mice was associated with sustained oncogenic Wnt/B-catenin signaling through Wnt4 and disheveled induction, E-cadherin repression, and glycogen synthase kinase-3B inactivation as the mice aged. Furthermore, microarray analysis of FXR KO mouse liver revealed altered gene expression profiles related to metabolism, inflammation, and fibrosis compared to WT liver recapitulating human HCC progression. Liver tumor bearing FXR KO mice showed elevated levels of interleukin 6 and signal transducer and activator of transcription 3 due to diminished expression of suppressor of cytokine signaling 3, a direct FXR target gene. STAT3 activation in conjunction with elevated TNFα and IL-6 levels has been shown to potentiate HCC formation.

Additionally, FXR can epigenetically silence the promoter of gankyrin, a proteasome subunit responsible for the degradation of retinoblastoma, p53, hepatic nuclear factor 4 alpha, and CCAAT /enhancer-binding tumor suppressor proteins. The loss of FXR in mice increased gankyrin expression to promote tumorigenesis. Interestingly, long-lived little mice with high basal FXR expression do not develop liver cancer with age or carcinogen administration due to insufficient gankyrin induction. FXR activation in human hepatocytes and hepatoma cells protected against cytotoxicity induced by cisplatin and other DNA-damaging agents. These findings support that in addition to its metabolic regulation, FXR also functions to modulate oxidative stress, inflammation, and cell proliferation to inhibit cancer development. Evidence also exists to suggest that FXR may act as a modulator of intestinal inflammation and a link between BA homeostasis and the intestinal microbiome. In the small intestine, FXR negatively regulates the expression of transporters involved in BA reabsorption while inducing the production and secretion of FGF19/Fgf15 to inhibit hepatic BA synthesis. Colon inflammation in Crohn’s disease patients and rodent colitis models is correlated with reduced FXR mRNA levels. The progression of colon inflammation is exacerbated in FXR KO mice while treatment with FXR agonist attenuated colonic tissue damage and immune cell activation. Conversely, FXR stimulation protected WT mice from chemical-induced colitis by reducing epithelial permeability, ulceration, and inflammatory cell infiltration. Moreover, FXR agonist-treated WT mice and differentiated enterocyte-like cells displayed lower pro-inflammatory cytokines and better preserved epithelial barrier function. In addition to its beneficial effects on intestinal function and inflammation, a connection between FXR and intestinal microbes was observed when ampicillin-treated mice had inhibited ileal expression of FXR, SHP, and FGF19/Fgf15. Expression of FXR and its target genes levels were rescued by combination treatment with CA, but not taurocholic acid, in ampicillin-treated mice suggesting that enterobacteria can enhance BA-mediated FXR activity via taurocholic acid deconjugation. Furthermore, intestinal inflammation in mice down-regulated FXR expression in a toll-like receptor 9 -dependent manner since the FXR promoter contains a response element to interferon regulatory factor 7, a TLR9- regulated factor. These preliminary findings suggest a possible role of intestinal FXR as a mediator between BA homeostasis, the gut microbiome, and host immunity to prevent excessive inflammation and maintain GI health. Examination of FXR in human HCC samples and cell lines has yielded further evidence to support its protective role against cancer formation. Marked reduction in FXR levels and activity were observed in human HCC samples compared to normal liver tissue. This reduction resulted from inhibition of hepatic nuclear factor 1 alpha activity on the FXR genepromoter by elevated pro-inflammatory mediators. The 3′ untranslated region of FXR mRNA was found to be a target of miR-421 and FXR downregulation by miR-421 promoted proliferation, migration, and invasion in human HCC cells. Decreased FXR levels in HCC cells also correlated with overexpression of active Ras resulting in strong activation of ERK1/2, a common characteristic of malignant cells. However, additional studies are required to determine whether dysregulated FXR activity increases the risk of HCC and CRC. One possible underlying cause of FXR insufficiency in humans is genetic variation in the gene itself resulting in diminished expression or function. Indeed, sequencing analysis of FXR in intrahepatic cholestasis of pregnancy patients revealed four functional heterozygous variants, three of which demonstrated functional defects in either translation efficiency or signaling activity. Additionally, FXR polymorphism identification analysis of European-, African-, Chinese-, and Hispanic-Americans identified a common, hypomorphic single nucleotide polymorphism with population allelic frequencies ranging from 2.5% to 12.1% . The in vitro transactivation activity of this hypomorphic SNP was lower relative to that of WT allele and human carriers of this allele showed significantly reduced hepatic SHP levels. Furthermore, the global FXR haplotype distribution between inflammatory bowel disease and healthy individuals was significantly different which emphasizes the link between FXR-mediated BA signaling and intestinal inflammation.48 Since chronic inflammation is widely considered a predisposition to cancer development, enhancement of FXR signaling appears to be a promising clinical target to not only normalize the BA dysregulation seen in obese and diabetic individuals but also combat chronic hepatic and intestinal inflammation. The appropriate circulation of BAs between the liver and small intestine is crucial to the maintenance of BA homeostasis and consequently, normal GI physiology. The ileum is where approximately 90% of secreted BAs are actively reabsorbed into the bloodstream by ASBT for transport back to the liver through the hepatic portal vein. Because of its predominantly ileal expression and central role in enterohepatic cycling of BAs, ASBT is another potential participant in the interplay between BA dysregulation and gut dysbiosis. In Caco-2 cells, 25-hydroxycholesterol and CDCA treatments greatly reduced ASBT promoter activity and mRNA levels through the actions of FXR, SHP, retinoic acid receptor, and retinoid x receptor . Mice fed a cholesterol-enriched diet exhibited downregulation of ASBT at both the mRNA and protein levels, decreased ileal BA uptake, and elevated fecal BA excretion. Interestingly, exposure of Caco-2 cells to pro-inflammatory factor IL-1B also caused a 65% reduction in ASBT mRNA level. Elevated levels of cholesterol in the intestinal lumen and pro-inflammatory mediators in the intestinal epithelium appear to down-regulate ASBT activity, thereby disrupting enterohepatic BA circulation.

Clusters were chosen from the most basal position on the shoot arising from the most basal bud. Flowering was estimated by percent of the cluster appearing to have caps fallen and flowers showing. At the point where 50% of the caps on flowers have fallen away, called anthesis, the cluster is considered at full bloom . Flowering is recorded as a percent estimate of the cluster in bloom. These clusters were then tagged with fluorescent tape loosely and followed subsequently for veraison and maturity. Records were taken every two to three days during each of the phenological stages. At each stage of monitoring, researchers calibrate observations with each other and with photographs from previous years. The Wang and Engel model uses a maximum temperature of 40°C, which may be the biological threshold for grapevine growth . The biological optimal temperature for grapevines is likely around 25°C , and when temperatures exceed 30°C, there are impacts on anthocyanins , and temperatures exceeding 37°C decreased coloration in grape berry skin and degradation of aromatic compounds .

Therefore, we include the variable of cumulative number of days when temperature reached a maximum at or over 40°C in our models of veraison, the only phenological stage that encounters these days, round pot with variety as a random effect . This study spanned four years and is ongoing to evaluate the sensitivity of different varieties to climate change. It is important to note that timing and duration of the winter pruning was variable, which could have introduced error because the timing of pruning can impact budburst . Some varieties were discontinued from the study because of death, disease, or pest damage. Some varieties were only included in later years of the study once they reached maturation. Measurements of percent budburst, flowering, and veraison were converted to GDD using R . For each stage, a linear model was fit with phenological development as a percent as the response variable and time as the independent variable. The fitted model was used to estimate the day a cluster reached 50% budburst, flowering, or veraison. Data were cleaned by removing individuals with illogical estimates for timing. It was determined for these removed points that too few measurements were made for those vines, and the individuals removed were from the year 2015. The limits for estimates were based on observational data. If budburst was predicted earlier than day 60 of the year, this individual was removed, because this was earlier than measurements were recorded.

Flowering was limited to day 111 of the year, and veraison was limited to begin at day 175 of the year. We obtained for each of the four years the GDD’s required to reach the three phenophases for an individual plant. These GDD’s were the response variable of the hierarchical models described in the next section. The days over 40°C from January until September were also quantified for each year. To quantify the variation in growing degree days across and within grapevine varieties, we used Bayesian linear mixed effect models as implemented in the package RStanArm . The default set of priors was used for the RStanArm package. A model using GDD’s with a base temperature of 10°C were compared against a model with base 0°C temperature. Models were fit using GDD with a base temperature of 0°C on the day of a phenological event as the response variable. Separate models were fit for the three phenological stages: budburst, flowering, and veraison. For the budburst and flowering stages, GDD was the response variable with “utility” as a fixed effect and “geography/variety” as random effects. For veraison, we included “utility” as a fixed effect, “geography/variety” as random, as well as “days above 40°C” as a random effect tied to variety. The climate data were summarized in R from the raw CIMIS data, and the cumulative measurements for each stage included the weeks prior to each stage. The explanatory models of maximum daily temperature, and cumulative number of days with temperatures reaching over 40°C, and year as fixed effects were incorporated into models for each stage. Overall, we added grape utility, in terms of wine or table grape or both, geographic groups, and country of origin as nested random variables .

The advantage to using a fixed effect model to predict GDD by variety is that we fill gaps by including data from other varieties’ responses to predict individual variety response. We quantify variety-level GDD by leveraging information from all varieties together. Rather than using an average for each variety by year, we utilize the temporal redundancy to estimate consistency across years, and we can see from the average of all varieties together which ones fluctuate the most during years with more change in climate. We used the posterior predictive check of a PSIS diagnostic plot to ensure khats were all less than 0.7. The preference for rstanarm to evaluate these mixed effects models is based on the Bayesian approach using MCMC, rather than restricted maximum likelihood estimation, which tends to underestimate uncertainties . This Bayesian approach estimates uncertainty for all the model levels, including our random effect of variety which contains 137 or less estimated parameters. When ELPD-difference was compared, the differences in log probability for the five models were almost completely within their individual standard errors. For this reason, we can consider all five models substantially predictive, but we chose the top model based on lowest ELPD-difference and biological relevance of the variables in the model. For veraison, the differences in log probability , were not within their individual standard errors . The models of veraison were improved by the addition of the variable, “days above 40,” referring to the cumulative number of days with daily maximum temperatures at or above 40°C. The genetically identified geographic origins provided by Bacilieri et al. Supplemental Information added predictive information to our final models for budburst, flowering, and veraison. We see differences in sensitivity to climate across stages for each of the geographic groups, visualized by the coefficient of variation over the four years analyzed . The intercepts reported in Supplementary Table 2, in terms of growing degree days, provide a predictive range to expect phenological variability from these groups. The range of phenological timing for specific cultivars can help match varieties with ideal climates and regions. There are varieties from each of these regions with the potential to be late ripening. From the Italian Peninsula, there is Dolcetto with a relatively early veraison and Aglicanico with a relatively late and variable veraison . The timing of stages can be extremely consistent, such as with Gamay Noir from Western Central Europe, but there can also be a wider range of timing like that of Mourvedre, from the same region. Therefore, while region is predictive, analyzing the timing for specific varieties is also useful when selecting alternative varieties for planting. years. Budburst had the highest coefficient of variation, likely due to the impact of conditions during dormancy . There may also be an accumulation of climatic impacts over the season resulting in the highest variability in timing at veraison. In a previous common garden experiment, round plastic planter the timing of maturity also had the largest standard error with more predictable timing for budburst and flowering . Sensitivity across stages does not have a strong correlation, but Budburst and Flowering seem to have the strongest relationship, with the highest R2 for the Balkans geographic region at 96% . The parameter estimates of the three models reported the highest sigma for variety for all three models. From an ecological perspective, a vineyard is a system that responds to its environment. This system includes the soil, international varieties, and the climate. We modelled the response of varieties’ phenological timing to climate, and the results present unique sensitivities to climate over 4 years.

Geographic origin and cultivated utility of grapes explain some of the variation seen in phenological timing, which we expect is driven by physiological differences. Accumulation of daily temperature in our model is strongly correlated with phenological stage occurrence, which agrees with past modelling of growing degree days and phenology . Previous models have used individual parameters for growing degree days and base temperature based on the cultivar . Duchêne et al. used daily maximum temperature rather than GDD in their models to predict phenology, and their models included a stage specific base temperature. Our model is unique by including variety specific response to cumulative days above 40°C. We expected this to impact the timing of veraison for some varieties with higher sensitivity to heat stress. The chosen model for veraison included the variable of “days above 40°C,” which is in part due to the timing of high heat days, typically occurring later in the season, during this stage. This model outranked models for veraison that nested geographic origin, indicating that the effect of high temperature is not variety specific. The general intercepts of the models for each stage predict the mean GDD required to reach each phenological stage, and the intercepts for each variety indicate the specific GDD requirement for each variety . The general intercept for the three stages was 199 GDD for budburst, 836 GDD for flowering, and 1,699 GDD for veraison . We may expect for other regions and in California’s future that heat stress may impact flowering as we see an increase in high heat events earlier in the growing season . The dominant hypotheses indicate that budburst may be less correlated with growing season temperature changes because it is more impacted by viticultural techniques and therefore sensitive to chilling time over dormancy . In the UC Davis ampelography vineyard, all vines are experiencing the same dormancy conditions, so the difference within years in timing of budbreak is explained by the varietal differences . However, across years, the lower sensitivity of budburst timing compared to flowering and veraison may be also be explained in part by the discrepancy in the dominance of climatic versus genetic controls for vegetative versus reproductive growth, respectively . Varieties may not be sensitive to temperature in the same way across stages, as the vine switches from vegetative growth to reproductive growth with the onset of flowering . The weaker relationship between budburst and cumulative temperature than the subsequent stages may be because flowering time and maturation are more strongly controlled by genetics . Furthermore, the dissociation between vegetative and reproductive growth makes it unclear how plants will adapt to climate change . While research shows viticulture is expanding to new territories all over the world , a crucial aspect to the success of the expanding viticulture into novel territories is matching the phenology to the local climate; agriculture will fail when introduced crops cannot adjust to new seasons . Climate change will not only change the varieties suitable for a region, but also the regions suitable for planting grapes . Failure to choose appropriate varieties for novel territories can impact natural ecosystems, an unintended adverse effect of expanding viticulture . A recent study modeling changes in viticulture territories under climate change scenarios predicted that 51 % of climatically suitable for growing winegrapes would become unsuitable . The intraspecific variation in heat thresholds for grapevines impacts the adaptation capacity of each cultivar . Previous authors suggest allowing cultivar turnover to prevent these major losses, which will depend heavily on what governments allow in Europe , while we are free to plant many different varieties in California. Among many strategies of adaptation to climate change, shifting to climatically more appropriate varieties has been widely suggested . Even with our current understanding of varieties’ climate niches, only a few existing cultivars are late ripening enough to avoid the warming predicted to occur during maturation in future climate scenarios . We identified many late ripening varieties that can be tested in future studies for suitability in California . International projects such as ADVIDCLIM are currently testing phenological models of grapevine with the expectation that varieties planted will need to change in future climate conditions . Hypothetical crosses between very late ripening varieties were modelled and still struggle to be late-ripening enough to endure the predicted 23-day shift and increase of 7°C expected by the end of this century . Within existing varieties, clonal variation does not offer a wide enough plasticity for adapting to climate change, however, taking advantage of existing varieties in warm regions to grow as alternatives is a promising strategy .