Evaluation of Improved Cowpea Genotypes for Yield and Resistance to Scab Disease in Uganda

Abstract

Cowpea is one of the most important legume food crops in Uganda. However, grain yields as low as 400 kg ha−1 have been recorded in farmers’ fields despite a grain yield potential of 3,000 kg ha−1. Cowpea scab is a major production constraint, causing yield losses of up to 100%. Three hundred ninety (390) improved cowpea genotypes were evaluated for yield and scab resistance for one (1) year at NaSARRI, Serere, Uganda using an alpha lattice design with two replications. The analysis of variance showed significant differences (p < 0.05) for grain yield, scab severity, incidence, and area under disease progress curve (AUDPC) among genotypes, seasons, and for genotypes by seasons interactions. The mean grain yield of 981.6 kg ha−1 was recorded across the cowpea genotypes with genotype, TVU-1280 having the highest grain yield of 1790.8 Kg ha−1. The cowpea genotypes; 1195K-1093-5-A, TVU-2968, SanZi, Taef-14-inhaca.E, TVU-205-8 and TVU-13485 had low scab severity(range:8.0 - 9.0).Cowpea genotypes; Taef-14-inhaca.E(33.7%), TVU-14633(26.7%), TVU-151144(30.6%), and Cosiriele (31.4%), had low scab incidence. Low AUDPC (range: 788.8-883.5) was observed in cowpea genotypes; 1195K-1093-5-A (775.0), TVU2968(788.8), TVU-14633-A (883.8), and TVU-13388 (857.5). Grain yield had a significant negative correlation with AUDPC (r = −0.2279, p < 0.001) and scab severity (−0.600, p < 0.001). Scab severity showed a strong significant and positive correlation with AUDPC (r = 0.6873, p < 0.001). The cowpea genotypes; 1195K−1093−5−A, TVU−2968, TVU−15114, SanZi, and Taef−14− inhaca.E could be used as breeding lines for introgressing scab resistance into cultivars with farmer preferred traits.