Genetics of trailing habit in yard long bean(Vigna unguiculata var. sesquipedalis(L) Verdcourt)

Abstract

A study has been undertaken in the Department of Plant Breeding and Genetics, College of Horticulture, Vellanikkara, to investigate the ‘Genetics of trailing habit in yard long bean (Vigna unguiculata var. sesquipedalis (L.) Verdcourt)’ and to identify the potential parents and superior cross combinations of trailing and bush types cowpea during 2002-04. Two trailing varieties and three bush varieties were used for study. The study revealed that pod yield, length of pod, number of pods per plant, days for first flowering and first harvesting were mainly influenced by allelic contribution where as duration of crop and pod yield can be used as selection parameters of crop improvement. Pod yield can be increased by selecting the genotypes having shorter days for first flowering and harvesting, increased number of pods per plant, lower number of seeds per pod, lower number of branches and higher number of pods. Trailing type, Lola has higher breeding value compared to Vyjayanthi and TC-99-1 and can be exploited for heterotic vigour for many of the yield attributes. The segregants can be used for fixing characters of both bush type coupled with trailing traits. Segregants of Lola x Pusa Komal can give higher pod yield and the yield attributes can be easily fixed in the segregating generations due to its low inbreeding depression. Trailing and bush characters showed a 3:1 monohybrid ratio and stem pigmentation (purplish: green) showed a dihybrid ratio of 9:7 in the F2 segregants of different combinations. Flower colour (purple: white) and pod colour (purple: green) showed a monogenic segregation ratio of 3:1 where as seed coat colour showed dominant epistatic gene action (12:3:1) in various crosses. Segregants can be further screened for higher pod yield coupled with tolerance to biotic and abiotic stresses, which is indicated as future line of work.