Abstract:
The genetic diversity of cowpea is narrow because the crop is self-pollinated. Gamma rays were used to increase genetic diversity of Hansadua, WC-36, ACC122WxWC-10, IT97K-819 and WC-10 parental genotypes. Selecting for earliness, high yields, disease resistance and high nutritional contents compared to parental controls and checks were done at M4 generation. The results showed significant wide variations in the responses of cowpea genotypes to gamma ray doses as LD50 and RD50. The estimated LD50 values were Hansadua (452.0 Gy), WC-36 (662.0 Gy), ACC122WxWC-10 (694.0 Gy), IT97K-819 (590.5 Gy) and WC-10 (591 Gy). Hansadua was the most sensitive to gamma radiation. The mass irradiation at the respective LD50 and RD50 values induced plant architecture to vary from indeterminate to determinate, semi-erect to acute erect, prostrate, spreading and some twinning. An increase in yields from 3.7t/ha in parent to 5.8t/ha in HanM4(12)(25) was observed. The ash values ranged from 2.93-3.56%, with HanM4(17)(1W) being highest. Carbohydrates ranged from 58.27-69.73% with HanM4(12)(5) being highest and protein ranged from 19.09-30.53% from the parental control with the highest in HanM4(12)(3). All the putative mutants were early maturing with days to 50% maturity of 42 to 61 days. HanM4(17)(1W) had 21.7% incidence of brown rust while HanM4(41)(HY31) recorded 10% incidence of golden mosaic disease. The results confirmed gamma ray induction can enhance yields, nutritional components, early maturity and disease tolerance/resistance of cowpea.
