Evaluation of green gram genotypes for agronomic performance under reduced light intensity and micro-catchments in Machakos and Makueni Counties, Kenya

Abstract

Green gram (Vigna radiata L.) is a hardy pulse crop, well adapted to marginal areas. In pursuit of strategies to evaluate agronomic performance of green grams in Machakos and Makueni Counties, Kenya, the study was carried out in Machakos Agricultural Training Centre in Machakos County and Kiboko sub-station of KALRO Katumani in Makueni County to: a) evaluate 40 green gram genotypes for agronomic performance at two locations, b) assess the effect of reduced light intensity on the agronomic performance of four green gram genotypes c) evaluate the effect of micro-catchments on the agronomic performance of four green gram genotypes, and d) evaluate the effects of reduced light intensity and micro-catchments (open and tied ridges) on the productivity of four green gram genotypes. Data was collected on several growth variables and subjected to Analysis of variance using Genstat statistical package, the means were separated using Least Significant Difference (LSD). The trial to evaluate 40 green gram genotypes for agronomic performance was laid out in Randomized Complete Block Design (RCBD). Accession GBK-022494A had the highest (103) number of pods per plant while Nylon-2 recorded the least number (19 pods) per plant in Machakos ATC during the 2011 short rain season. GBK-022501A had the highest seed yield (4.7 ton ha-1) followed by GBK-022494A with 4.5 ton ha-1. In Kiboko GBK-022494A had 115 pods per plant as compared to GBK-018633A with 27 pods per plant. Accession GBK-022494A attained 7.4 ton ha-1 and Nylon with 5.8 ton ha-1. It was concluded that GBK-022494A was the best performer in Kiboko while GBK-022501A was the best performer in Machakos ATC. To assess the effect of reduced light intensity on agronomic performance, four green gram genotypes; GBK-022494A, GBK-022501A, GBK-022502A and Nylon-1 were used. The experiment was laid in a split-plot arrangement with shading as the main plot at two levels; shaded and non-shaded while the 4 accessions were the sub-plots. The green gram accessions revealed significant (P≤0.05) differences in their response to shading as measured by number of seeds per pod and number of days to maturity at Machakos ATC and number of seeds per pod at Kiboko during the 2012 short rain season. The values of the variables were higher under shade net during the 2012 short rain season while the values of the variables were higher under direct solar radiation in both sites as during 2013 long rain season at both sites. In order to evaluate the effect of micro-catchments on the agronomic performance of green grams, the trials were laid out in split-plot arrangement. The accessions had better agronomic performance under tied ridges. To evaluate the effects of integrated packages incorporating reduced light intensity and micro-catchments on productivity of four green gram genotypes the experiment was laid out in Split-split plot Design and replicated three times. The results indicated that agronomic performance was better under the direct solar radiation than under the shade net and that these traits performed better under the tied ridges at both sites.