Evaluating the yield performance of cowpea genotypes developed for scab resistance
Abstract
Cowpea (Vigna unguiculata L. Walp) is the 4th most grain legume grown in Uganda making it an important crop to many livelihoods especially in the Eastern and Northern region were the crop is widely grown. Cowpea yields in Uganda are still low and this has been attributed to the devastating scab disease that causes yield losses of up to 100% in conditions of no management strategies to susceptible varieties. Scab disease affects all the above ground parts the plant causing the development of silvery grey, circular to oval lesions on the leaves, stems, petioles, peduncles and pods. At the anthesis stage, this is where the crop causes most of the yield losses by causing the abortion of young pods or remain attached to the plant as mummified black masses. Many scholars have reported that the use of resistant cultivar is the most effective and efficient strategy for cubbing the damages caused by the disease. This research was therefore conducted to screen for scab resistance and access the yield and yield components of genotypes developed for scab resistance. The study was carried out in Makerere University Agricultural Research Institute- Kabanyolo (MUARIK) with 190 genotypes which were evaluated in 15 x 13 alpha lattice design with two replications during the second season of 2018. Data was collected on scab damage both vegetative and podding stage, 50% maturity, yield components (number of peduncles per plant, number of pods per peduncle, number of pods per plant, and number of seeds per pod) and grain yield. Results showed significant difference among genotypes for scab, 50% maturity, and yield components (P ≤ 0.05) except number of pods per peduncle (P > 0.05), and grain yield (P < 0.001) suggesting a genetic variability among the genotypes. Most genotypes were either moderately resistant or highly resistant to scab infection. Some of these genotypes were high yielding. Genotypes ACC 122W x NE 15 KABF4:5/2, Secow 3B x IT96D-610KABF4:6/16 Brown, Secow 4W x IT99K KABF4:6/10 and WC3B x NE 48 KABF4:6/3 were high yielding. However, genotype WC3B x NE 48 KABF4:6/3 was both high yielding and highly resistant to scab. This can be used as a parental line in cowpea improvement programs for developing high yielding cowpea scab resistant varieties.