MSc

The present study entitled “Evaluation of cowpea [Vigna unguiculata (L.) Walp.] genotypes for yield and resistance to pulse beetle [Callosobruchus spp.]” was carried out at farmer’s field, Kayamkulam during 2015-2017, with an objective to evaluate cowpea genotypes for yield and resistance to pulse beetle.
The study was conducted in two experiments. In experiment-I, yield and resistance to pulse beetle was evaluated in a Randomised Block Design (RBD) with three replications using 30 genotypes collected from different places. Experiment-II was to study the seed morphological and biochemical factors associated with resistance to pulse beetle in five relatively resistant genotypes and five relatively susceptible ones which were identified through experiment-I.
The field experiment revealed that the genotype T1 (Ambalappuzha local) showed the highest mean values for days to 50 per cent flowering, length of main stem, pod weight, pod length, number of seeds pod-1, 100 seed weight and crop duration. The maximum yield plant-1 (32.91g) was obtained for the genotype T29 (Sreya) followed byT14 (Alathur local) and T7 (Dhavengarae local), whereas the minimum yield plant-1 (11.07g) was for the genotype T13 (Hridya). Thirteen genotypes were found to be infested under field condition and only very low seed damage via carry over population was noticed. The characters studied were found to be significant for all the genotypes evaluated. The pod weight exhibited the highest GCV (47.73%) and PCV (52.12%). Heritability was high for all the characters except number of primary branches plant-1, number of pods plant-1 and seed yield plant-1 which possessed moderate heritability. GA (% mean) was high for all the characters except crop duration. The association analysis revealed highly significant positive correlation for 100 seed weight, days to 50 per cent flowering, crop duration, number of seeds pod-1, pod girth, and pod length with seed yield both at genotypic and phenotypic levels. The path analysis revealed that 100 seed weight, number of pods plant-1 and number of seeds pod-1 had the maximum positive direct effect on seed yield plant-1.
In no choice confinement test under experiment-I, there were significant differences among the genotypes in terms of oviposition, percentage seed damage and percentage seed weight loss. T2 (Kayamkulam local-1) had the least egg load while more eggs were laid on seeds of T29 (Sreya) and T1 (Ambalappuzha local). The highest percentage seed damage and the highest percentage weight loss were recorded for T13 (Hridya) and T27 (Bijapur local) respectively. The lowest percentage seed damage and percentage seed weight loss were observed for the genotype T7 (Dhavengarae local).
In the study of seed morphological and biochemical factors associated with resistance under experiment-II, it was found that seed coat texture, seed coat colour and protein content of seeds were found to have no influence on resistance to pulse beetle. However, total phenol content of seed was having significant negative correlation with percentage seed weight loss. An index score was worked out to find out genotypes with good yield and relative resistance to pulse beetle. It was observed that the genotype T7 (Dhavengarae local) had the highest index score followed by T14 (Alathur local).
The present study revealed that the genotype T7 (Dhavengarae local) was found to be a good yielder with relative resistance to pulse beetle followed by the genotype T14 (Alathur local). Hence these genotypes can be recommended for future breeding programmes.