Yield of scarlet eggplant (Solanum aethiopicum L.) as influenced by planting date of companion cowpea

Growth and fruit yield of scarlet eggplant were examined under intercropping with an erect and semi-spreading early maturing cultivars of cowpea in an additive intercropping model with scarlet eggplant as the main crop, in two dry seasons, under irrigation. Cowpea was planted simultaneously with scarlet eggplant, 2 and 4 weeks ahead of scarlet eggplant. Land equivalent ratio (LER) of the intercrops ranged from 1.38 to 1.94, indicating that the intercrops were more productive than the pure crops. Reduction in fruit yield of the main crop, when intercropped with the semi-spreading cowpea cultivar was significantly (p < 0.01) greater than with the erect cowpea cultivar. Simultaneous planting of cowpea and scarlet eggplant produced 90-99% the fruit yield of sole scarlet eggplant, while planting cowpea 2 and 4 weeks ahead produced 65-80% and 58-60% of sole crop yield, respectively. Competition between component crops was however most favourable for both cultivars of cowpea when planted 2 weeks ahead of scarlet eggplant. Planting cowpea 2 weeks ahead of the main crop also produced the highest LER most likely due to more efficient utilization of sunlight, water and soil nutrients. Simultaneously planting cowpea and transplanting scarlet eggplant, is recommended for such additive intercropping system, aimed at full yield of scarlet eggplant with additional cowpea for food, income or fodder. (c) 2005 Elsevier B.V. All rights reserved.