Although the Brazilian flora is well represented, a large part of the collection constitutes non-native species. For example, the collection includes some exotic species of Myrtaceae, a botanical family that characteristically accumulates volatile compounds in the leaves. The goal of the present study was to assess the composition of leaf essential oil of three exotic species of Myrtaceae species growing in the BGRJ: Melaleuca leucadendra , Lophostemon confertus Peter G. Wilson & J. T. Waterh. , and Ugni molinae Turcz. The former two are woody-fruited species native to Australia, while the latter is native to Chile and is characterized by its production of pleasant tasting berries, as most South American Myrtaceae species are. The Melaleuca genus comprises nearly 300 species, most of which are endemic to Australia. Species of Melaleuca thrives in many kinds of environments, including swampy or temporarily inundated lands, poor or degraded soils. Popularly known as tea tree, the leaves of these species produce an abundance of essential oils that possess medicinal properties and are useful as flavor ingredients in the food industries. Melaleuca leucadendra grows up to 40 m in height and has a thick trunk that may reach 1.5 m diameter in its original habitat. This species is conspicuously distinguished by its white, very thin bark that much resembles sheets of paper. Three chemotypes have been identified for M. leucadendra based on the essential oil composition. They are characterized by a high content of eugenol-type phenylpropanoids or terpenoids, of which γ-terpinene and terpinolene predominate among the monoterpenes.
Different chemotypes of the leaf essential oil have also been correlated with the geographical location of plants. Under specific agroforest conditions and depending on the geographic locale, 1,8-cineole or a combination of 1,8-cineole/α-terpineol/limonene may be present and characterize the chemotype. Several parts of the plant M. leucadendra are traditionally used for their anti-parasitic, antiseptic,mobile grow rack and insect repellent activities, and the leaf essential oil is used as an antifungal. The 1,8-cineole chemotype of M. leucadendra leaf oil has been found to be active against Bacilus cereus and Staphylococcus aureus and a series of four other fungi while the methyl eugenol chemotype is an effective virucide against Herpes simplex virus type 1. Mild antioxidant and anti-hyaluronidase abilities have been observed for the former oil chemotype. The ethanol extract from the branches of M. leucadendra is highly selective against Tripanosoma brucei. The essential oil of M. leucadendra, pure or mixed with other oils, is ineffective in inducing mortality in Aedes, Anopheles, and Culex larvae, but significant irritant and repellent properties against Aedes aegypti females have been observed in experiments using the excito-repellency test chamber . An anti-feeding assay using gypsy moth larvae and the leaf ethanol extract of M. leucadendra led to the isolation of -nerolidol as the active component. Lophostemon confertus is a large to very large evergreen tree native to open forest and rainforest ecotones on the east coast of Australia that may reach 25 to 40 m in height . Due to its pest resilience, tolerance to pollution, and excellent shade-providing capacity, it has been used as street tree in the cities of various countries. Leaves of L. confertus collected in Queensland have been shown to afford low yields of volatile oil that contained up to 33% α-pinene plus 20% limonene; with aromadendrene and spathulenol being relevant among the sesquiterpenes. Ugni molinae is an evergreen shrub that is native to temperate rain forests in Chile .
Apart from exceptional cases, this species grows to around 2 m in height. It is cultivated as an ornamental shrub and produces an excellent berry suitable to use in jelly, jam, cakes, liqueurs, etc.. It was eventually introduced in some Pacific British colonies, and thereafter being popularized as the New Zealand cranberry. The leaves of U. molinae exhibit astringent and stimulant properties and have been used in folk medicine to treat several kinds of diarrhea. Additionally, the leaves contain triterpenes that exhibit topical anti-inflammatory activity. To the best of our knowledge, no reports exist describing the leaf volatile compounds of this species.As a result of population growth and agricultural expansion, few forests are remaining and they are highly degraded, causing losses in traditionally important nutritious foods, medicines and other useful products leading to food insecurity. Furthermore, soil fertility has drastically fallen with fallow shortening and steadily disappearing to make room for continuous farming. There is a need to develop emerging plants like Moringa. Moringa oleifera, also known as horse radish, benzolive tree or drumstick tree is one of the world’s most useful and nutritious plants. Moringa has both therapeutic and nutritional values. It is also used in animal forage, biogas, domestic cleaning, biopesticide and water purification. In fact, almost all parts of the tree are useful and have long been consumed by humans. It is the only genius of the family Moringaceae and is grown mainly in the semi-arid, the tropical and subtropical regions . It is adapted to a wide range of soil types but grows best in well drained loam to clay loam, neutral to slightly acidic soils, but cannot withstand prolonged water logging . It does best where temperatures range from 26˚C – 40˚C and annual rainfall totals at least 500 mm. Moringa is propagated sexually through seeds, and vegetatively through stem cuttings. Its recent introduction as a field crop has required propagation through seeds which are usually planted in the nursery using a light media , mixture of soil and sand, respectively.
The germination of M. oleifera is hypogeal, meaning that the cotyledons remain beneath the soil surface suggested that the use of garden/topsoil substrate leads to a germination percentage above 70% after three weeks. Germination occurs within 5 – 30 days, depending on the age of the seed, soil or media type and pretreatment method used, which might include: cracking the shells, soaking seeds with shells, dehulling seeds, and soaking seeds for 24 hours then putting in a plastic bag and storing in a warm place. Some authors indicate the necessity of soaking or priming the seeds for 24 hours before sowing.When factors like substrate quantity, hydric availability, thermal properties and absence of physical obstacles for the emergence of some species are improved, the seeds have better conditions for germination and emergence, and the seedlings better conditions for initial development. Frequently, farmers are limited by the use of one or few commercial substrates, usually of high cost and not easily accessible, often not very common in the western highland regions of Cameroon, where there is a weak technical and commercial support for horticultural activities. However, in the above area, it is possible to find many byproducts from the traditional agriculture and livestock activities, which could be used in the formulation of competitive alternative substrates, of low cost. Knowledge on the optimum manure requirements would significantly assist in scaling up M. oleifera production as an edible vegetable. Previous works focused mainly on nutritional values and uses whilst research on establishment and growth has not received much attention despite the growing awareness that M. oleifera production can be adversely affected by nutrient status of soil or media. Often during germination and growth of Moringa seeds, seedlings show symptoms of stunted growth and yellowing of leaves, resulting in death or reduced growth. This has been attributed to low initial soil nutrition and water logging in some cases. There is therefore a need to use locally available soil fertility amendment resources such as poultry manure to improve the establishment and growth of Moringa in resource constrained soils of the Western highlands of Cameroon have shown that poultry manure can serve as a soil amendment to improve soil nutrient status.
It is a source of carbon and nitrogen for microorganisms in the soil, improves soil structure, lowers the temperature at the soil or media surface, helps in seed germination and increases water holding capacity particularly in sandy soils, stabilizes soil pH, increases soil organic matter and ultimately improves plant growth and yields. In Cameroon, there is little technical information on the production of quality seedlings of the Moringa plant except those of. The latter authors discussed some aspects of germination but none addressed the influence of soaking and substrate composition with poultry manure on germination and seedling growth in the western highlands agro ecological zone. Considering the importance of Moringa, the present study was carried out with the objective of assessing the effect of four soaking durations and eight substrate compositions on the germination and initial seedling growth of Moringa in polyethylene bags in the nursery.The soil used was the topsoil of a Hapli-skeletic Cambisol of the YWHRGP. The sand was collected from the crossing German trench where it is equally fetched by the local populations for constructions. The poultry manure was obtained from a local farmer in Bamenda. The different substrate mixes were obtained from a number of buckets of soil,ebb and flow table sand and PM depending upon the amount required. A 10 liter bucket was used to measure the different materials in their different proportions as indicated above and was properly mixed with the hands as is customary with the farmers in the field. These substrates were chosen because of their availability to farmers. Equally some of these substrates are widely used in the production of seedlings of different annual plants, fruit and forestry species. The soaked seeds were obtained by soaking 3 lots of 96 seeds for 12 days, 8 days, and 4 days, respectively. The soaked seeds with the 96 unsoaked seeds were planted the same day. The sowing was conducted on the 18th of August 2013 in filled polyethylene bags at 3 cm depths and the top of the bags were covered with hashed dry grass to prevent splash soil loss.Seed germination is initiated through rapid water uptake, followed by the activation of metabolic mechanisms leading to the first visual signs of germination known as the protrusion of the radical. Thus, water plays a fundamental role in understanding seed biology, particularly germination and plant development.
The principal factors influencing seed germination are temperature, water, oxygen and light. Temperature is the most important, as it affects both the germination percentage and germination rate. At 25 DAS, soaking durations of 0 day and 8 days showed the highest germination percentages, while seeds soaked for 12 days occupied the least position . The highest germination percentage of 68.7% is in agreement with the results obtained by in the sudano-sahelian zone of Cameroon, where 69.6% of seeds had germinated at 25 DAS. The average percentages of germination of this plant in India, West Africa and other zones of Cameroon, were all above those obtained in this study. Different pretreatments and differences in the agro ecological zones are likely responsible. Although, some scientific results show that soaking is an option for improving the Moringa seed germination, other reports consider it unnecessary. Seed priming improves germination and stand establishment and induces tolerance against adverse conditions like abiotic stress, especially during emergence and early seedling growth. Moringa seeds are not an exception, and it was reported that 12 h of soaking increased the germination of moringa seeds in the western highlands of Cameroon. Our results demonstrate that long duration pre-hydration negatively influences the germination process as well as the post germination behavior which probably affects the establishment in the field. Besides, it was demonstrated that pregermination for 48 h affects the percentage of seed germination negatively. This could be due to the fact that seeds soaked for a long time, can undergo putrefaction due to fungi attack. The results obtained in this study when soaking duration reached 12 days is in conformity with those of the latter investigators. When the germination percentage was analyzed, the control attained 68.7%. This confirms that seeds of this plant achieve high germination in spite of pre-germination treatments. Watering of the germination bags every day by rain until field capacity was attained could be another factor influencing germination. stated that the excess of humidity on the substrate may provoke germination losses and diminishing of the root growth and the aerial part of some tree species like moringa.