A testing of four modeling methods across 18 species with different levels of ecological specialization using six different sample size treatments and three different evaluation measures revealed that MAXENT was the most capable of the four modeling methods in producing useful results with sample sizes as small as 5, 10and 25 occurrences. MAXENT also predicted the largest area of all modeling methods at sample size 5 and remained fairly level at sample sizes of 25 and above . In the present study MAXENT was used to develop the model using very low sample size over a smaller area of 16,579 km² to predict the climatic suitability of the target species.
The model was able to bring out interesting insights on the climatic parameters which are playing an important role in the survival of the target species; the model defining precipitation as the most important predictor for the model grow lights. During field survey it was observed that occurrence areas are mostly hot and humid with high rainfall and the possibility of precipitation playing an important role in maintaining the population of the target specie sis quite relevant. The basic target for conservation works are on those species that are under high threat and those species in high threat category usually have low occurrence and it will be insignificant for conservationist unless working models are developed for these threatened species. In this study only climate data was used as our target species is plant species and climate plays a major role for its well being however, this does not negates the possibilities of anthropogenic and other biological factors contributing to the habitat loss and low occurrence of species.
The predication ability of the model with low sample size over a smaller area can be used to develop a mosaic of prediction models in areas where occurrence points are less and are in considerably distant pockets. Our study was able to give a success rate of 70% with just4 sample over a small well defined area. Bottle gourd originated in Africa and from there, it spread over the world . At present, it is grown in many countries including Bangladesh, India, Malaysia, Indonesia, Japan, China, The Philippines, Taiwan, Thailand, South Africa and Sudan . Bottle gourd fruits are used as cooked vegetables. Its leaves and tender stems are used as delicious and nutritious vegetables.Each 100 g bottle gourd contains protein1.1 g, carbohydrate 15.1 g, fat 0.1 g, minerals 0.6 g, and several vitamins .Bottle gourd is a popular winter vegetable in Bangladesh. The climatic condition of winter in Bangladesh favours better growth and yield of bottle gourd but hot and humid summer and summer rainy season gives poor yield. The average day temperature of 20˚C 27˚C with lower night temperature of 18˚C 23˚C is optimum for growth and fruiting.
Anthesis of flower in different cultivars is influenced by both temperature and rainfall. Bottle gourd is widely cultivated throughout the country. Its cultivation and uses are wide in winter season but nowadays it is cultivating during summer and rainy season. At present,led grow lights the acreage and annual production of bottle gourd are 7217 ha and 85,267 tons respectively in Bangladesh with an average yield of 11.81 tons per hectare ,which is very low compared to other countries.The identification and utilization of the most heterotic and useful crosses are very important in hybrid approach to make the commercial cultivation of hybrid beneficial . So a well-planned and dynamic bottle gourd breeding research programme is needed to meet the required demand of bottle gourd production.The understanding of the nature and magnitude of gene action is an important factor in developing an effective breeding programme. The diallel analysis provides an efficient means of rapidly obtaining an overall picture of the genetic control of a character in a set of parents in the early generations.
The analysis of combining ability helps in selecting suitable geno types as parents for hybridization and crosses for characterizing the nature and magnitude of gene action involved in quantitative traits . The use of contrasted lines in breeding programmes could contribute to create high yield varieties . On the other hand,plant selection for high yield can be effective only if the variables under selection have high heritability values . In Bangladesh context, the information on this aspect of bottle gourd is not sufficient. This study would be very important in developing hybrid varieties for Bangladesh conditions. Therefore, the present investigation was undertaken to investigate the genetic architecture of yield in bottle gourd.