Jackfruit (Artocarpus heterophyllus Lam.) Diversity in Bangladesh: Land Use and Artificial Selection(1)

摘要

Jackfruit ( Artocarpus heterophyllus Lam.) Diversity in Bangladesh: Land Use and Artificial Selection. Bangladesh is often recognized as a secondary center of diversity for jackfruit (Artocarpus heterophyllus Lam.) and is expected to harbor important genetic diversity of this underutilized tree crop. Unfortunately, genetic erosion is occurring before this rich local resource has been documented and utilized for potential crop improvement. The aim of this study was to carry out a village-based survey and make morphological measurements to document and assess jackfruit diversity across trees associated with a gradient of three locations/habitats (homesteads, public lands, and forest or fallow lands). We also tested the hypotheses that cultivated jackfruit found in homesteads exhibited positive selection pressure for characteristics desirable in the market, and that the tree location reflected its history of origin and human selection. This was accomplished using 28 standardized morphological descriptors and represents the first large-scale assessment (900 trees) of jackfruit diversity in multiple locations (nine villages). Among the descriptors studied, those most closely associated with jackfruit marketability showed a trend for selection among the trees located in homesteads. Both fruits and leaves were larger in plants on homesteads compared to plants in forest/fallow lands, and fruit quality was significantly higher in homestead trees compared to the other two location categories. However, 18.7% and 23.7% of the fruits found on public lands and forest/fallow lands, respectively, were still considered to be of excellent fruit quality and tree vigor was significantly higher in jackfruit in forest/fallow lands compared to the other location categories. The combination of high tree vigor and presence of excellent fruit quality among jackfruit in forest/fallow lands suggests that the "wild" Bangladeshi jackfruit germplasm, which is considered inferior for market and is being negatively impacted, has valuable genetic diversity to contribute to jackfruit cultivation. Furthermore, sampling across a gradient of habitats may enable the detection of possible trends resulting from domestication pressures.