Legume Cover Crops for Sustainable Eggplant Production in Haiti

Haitian farmers depend on tillage and hand weeding for managing weeds in vegetable crops due to limited financial resources for purchasing herbicides and loss of laborers to urban migration. The use of cover crops was proposed as a means of suppressing weeds and plant-parasitic nematodes during the off-season before planting vegetable crops. The objectives of the study were to compare the effects of leguminous cover crops on weed and root-knot nematode ( Meloidogyne spp.) suppression before and during a subsequent eggplant ( Solanum melongena ) cash crop and evaluate the effects of the cover crops and supplemental fertilizer on eggplant growth and yield. In Summer 2018, three legume cover crops, velvet bean ( Mucuna pruriens ), cowpea ( Vigna unguiculata cv. Iron Clay), and sunn hemp ( Crotalaria juncea cv. Tropic Sun), and a no cover crop control were evaluated at Camp-Perrin and Ducis, Haiti. Cover crops were assigned to the main plots of a split-plot experimental design and ‘Florida Market’ eggplant with or without supplemental mineral fertilizer comprised the subplot treatments. Data were collected on cover crop shoot biomass accumulation, weed and plant-parasitic nematode suppression, and eggplant growth and yield. Cover crop fresh shoot biomass with sunn hemp and cowpea was higher than velvet bean at Camp-Perrin and sunn hemp biomass was higher than cowpea and velvet bean at Ducis. However, both sunn hemp and cowpea resulted in lower weed biomass than the weedy control during the cover crop phase. During the eggplant crop, only sunn hemp reduced weed biomass to less than the control. Sunn hemp produced the tallest eggplant plants with the highest shoot biomass and fruit yields, and fruit size was larger with sunn hemp than with the weedy control. Plant-parasitic nematode populations were low at both sites and not significantly different from the control. The results indicate that sunn hemp can be used as a cultural weed management method to suppress weeds and enhance eggplant yield in Haiti.