Development of stabilised population of cowpea segregants(Vigna unguiculata (L.) walp.) with high protein content and grain yield

Abstract

Cowpea (Vigna unguiculata (L.) Walp.) is an important pulse crop providing good source of protein and often referred to as poor man’s meat. It is a versatile crop, of which seeds are utilised as pulse, green pods as vegetable, leaves as forage and helps in restoring soil fertility. Many reports have indicated protein content of more than 30 per cent in certain cowpea genotypes, but at the cost of yield. Hence, the present study was proposed to develop cultures with high grain yield and protein content. The present study was conducted at Department of Plant Breeding and Genetics, College of Horticulture during 2017-2019. Twenty three lines with high yield and protein content in the F3 generation of two cowpea crosses H10 (Anaswara X PKB 3) and H11 (Anaswara X PKB 4) identified in previous studies formed the working material. These lines were evaluated in F4, F5 and F6 generations and pedigree selection was performed to select superior plants. Observations were recorded on 12 characters viz. plant height, number of branches, days to first flowering, days to first harvest, days to last harvest, number of pods per plant, length of pod, pod weight, number of seeds per pod, hundred seed weight, grain yield per plant and protein content. The F4 generation of both the crosses exhibited lower mean value for most of the characters than the parent Anaswara, but recorded moderate to high variance and range. Higher mean value was observed for days to first flowering, first harvest, last harvest, number of branches and protein content. Genetic parameters indicated that GCV was moderate for length of pod, number of seeds per pod, and hundred seed weight and high for grain yield per plant. High heritability coupled with moderate to high genetic advance was recorded for number of pods per plant, number of seeds per pod, hundred seed weight, and grain yield. Correlation studies in F4 generation revealed that grain yield was positively correlated with plant height, number of branches per plant, number of pods per plant, length of pod, pod weight, number of seeds per pod and test weight. There was non-significant correlation between grain yield and seed protein content. Further path analysis confirmed that high positive direct effect on grain yield was given by pods per plant, number of seeds per pod and hundred seed weight. Based on these observations, characters like number of pods per plant, hundred seed weight and number of seeds per pod were simultaneously included along with grain yield for setting selection criteria to select superior individual plants. Based on these set criteria, 13 individual plants from cross H10 and 10 plants from cross H11 were selected and forwarded to F5 generation. In F5 generation, mean values for number of branches, number of pods per plant, number of seeds per pod and protein content were higher than that of Anaswara with sufficient variance and range. GCV was moderate for number of branches, length of pod, pod weight, hundred seed weight and grain yield per plant. High heritability with moderate to high genetic advance was recorded for number of pods per plant, length of pod, pod weight, number of seeds per pod, hundred seed weight and grain yield. Based on the segregation pattern observed, the plants were grouped into two different categories - one with medium long pods and small seeds closely packed within the pod and the other type with long fleshy pods and bold seeds. Hence, separate selection criteria was developed for both the types comprising of characters like number of pods, number of seeds per pod, pod length, hundred seed weight, grain yield and protein content. Based on these set criteria, five individual plants from cross H10 (one type 1 and four type 2) and 17 plants from cross H11 (five type 1 and twelve type 2) were selected and forwarded to F6 generation.

In F6 generation, mean value was higher than Anaswara for number of pods per plant but lower for plant height, days to first flowering, days to first harvest, days to last harvest, pod length and hundred seed weight. For other characters, mean value was comparable to Anaswara. Moderate GCV value was recorded for length of pod, pod weight and hundred seed weight. High heritability with high genetic advance was recorded for length of pod, pod weight and hundred seed weight. Separate selection criteria was developed for the two categories of plants and total five individual plants were selected, one from cross H10 and four from cross H11. The selected plants from F6 generation were subjected to organoleptic evaluation to find its suitability to be used for vegetable purpose. Three plants of type 2 and one plant from type 1 were found promising. The identified lines, H11-3.9-1-7-13-7, H11-3.9-1-1-18-13, H11-49.7-1-8-10-15, H10-71-16-1-9-15-12, and H11-2-20-3-14-16-12 can be evaluated in replicated yield trials and tested for stability over locations and seasons