Effects of partial leaf defoliation of cowpea (Vigna unguiculata (L) Walp) on grain yield

Abstract

Cowpea is the third most important legume food crop in Uganda. Low grain yield of about 400Kg ha-1 has been recorded in farmers’ fields despite the grain yield potential of 3,000 Kg ha. This has been attributed to several production constraints such as pests and diseases, soil infertility, drought and water logging. Dual-purpose production of cowpea is most common in subsistence farming systems. Despite the nutritional and economic importance of cowpea like providing both leaf vegetable and/or grain, much work has not been done in the effects of defoliation in cowpea production, largely, farmers harvest tender leaves for consumption. Therefore, the study aimed at determining the effects of leaf defoliation on the 3 selected cowpea varieties growth and yield at different levels of defoliation intensities. The 3 selected varieties of cowpea were studied for 2 seasons; 2021B and 2023B at the faculty of agriculture and animal sciences, Arapai campus-Busitema University using Randomized Complete Block Designs (RCBD) with 3 replications. The analysis of variance showed significant differences (P<0.05) for grain yield and yield related components across all treatments, varieties, seasons, treatments by varieties. The mean grain yield of 937.9 Kg hax-1 was recorded across the cowpea varieties in season 2021B. Cowpea varieties, Secow2w was ranked as the best performed variety with the grain yield (1346 Kg ha-1), followed by variety, Narocowpea6 (787Kg ha), lastly Echrikukwai variety (681 Kg ha-1) respectively in season 2021B and the mean grain yield of 937 Kg ha-1 was recorded across the cowpea varieties in season 2023B. Cowpea varieties, Secow2w was ranked as the best performed variety with the grain yield (1332 Kg ha), followed by variety, Narocowpea6 (795Kg ha-1), lastly Echrikukwai variety (682 Kg ha) respectively in season 2023B. However, all varieties yielded dependent on the level of defoliation and high yields were recorded in season 2021B (938Kg ha-1) as compared to 2023B (937 Kg ha-1). Keywords: Cowpea defoliation; Levels of defoliation intensities; Echirikukwai, Secow2W, Narocowpea 6, Uganda; Yield performance.