GxE interaction of semi-erect cowpea genotypes

Abstract

Experiments on “G x E interaction of semi-erect cowpea genotypes” were carried out at the Department of Olericulture, College of Horticulture, Kerala Agricultural University, Vellanikkara, Thrissur during Kharif, Rabi and summer 2004-2005.

Fifty accessions of cowpea collected from various parts of Kerala were used for the study. The study was aimed at identification of stable high yielding and dual purpose semi-erect cowpea accessions over different seasons.

With regard to yield and yield contributing characters, summer season was found to be best. The performance of all the accessions during Rabi was inferior as compared to Kharif and summer.

The accessions VS-1177, VS-1025 and VS-1179 performed better with a green pod yield of 9.5 tonnes, 6.9 tonnes, 6.2 tonnes per hectare respectively and a seed yield of 3.3 tonnes, 2.1 tonnes, 2.3 tonnes per hectare respectively tonnes per hectare. Along with these three accessions during summer the accessions VS-1172 and VS-1170; during Kharif the accessions VS-1174 and VS-1042 during Rabi the accessions VS-1175 and VS-1015 were also superior.

The pest and disease infestation scenario during cultivation showed that the accession VS-1111 had a pod borer infestation below 2 per cent and can be recommended as a resistant variety. The coreid bug infestation was maximum during summer followed by Kharif and was nil during Rabi. None of the accessions were found to be resistant to coreid bug. The incidence of aphids was lowest during Kharif followed by summer and Rabi. The accessions VS-1230 and VS-1231 were free from aphid attack during all the seasons and can be considered as resistant varieties. There was no incidence of anthracnose during Rabi season. Considering all the seasons, the accessions VS-1294, VS-1047, VS-1171, VS-1286 (Varun), VS-1276 (Kanakamony), VS-1179, VS-1213, VS-1160, VS-1263, VS-1032, VS-1266 (Kairali) and VS-1248 were free from anthracnose. The incidence of collar rot was lowest during summer followed by Kharif and Rabi. There was no incidence of mosaic during Rabi.

The study on analysis of variance revealed the presence of considerable variability for most of the characters among the genotypes. The magnitude of PCV was higher indicating a higher degree of environmental fluctuation in the case of green pod yield per plant (42.13), number of pods per plant (35.75) and seed yield per plant (35.33). GCV also revealed the same pattern of genetic variability as shown by the PCV for all the characters. High heritability of more than 60 per cent was noticed for characters like 100 seed weight followed by pod length, seed yield per plant, green pod yield per plant, number of pods per plant, number of seeds per pod and number of clusters per plant. The estimates of genotypic correlation coefficient were higher than the phenotypic correlation coefficient.

Considering the G x E interaction, the accessions VS-1177, VS-1025 and VS-1179 were highly adaptable for green pod yield and seed yield per plant during all the seasons. Hence these accessions can be recommended as dual purpose, adaptable semi-erect cowpea for large scale cultivation throughout the year in Kerala.