Genetics of growth habit and photoperiodic response to flowering time in dolichos bean (Lablab purpureus (L.) Sweet).

Abstract

Development of photoperiod insensitive and determinate type cultivars is one of the major objective of Dolichos bean breeding. For this, an understanding of the genetics of photoperiodic sensitivity to flowering time and growth habit is a prerequisite. Genetics of photoperiod sensitivity and growth habit was investigated in two crosses, HA 4 × GL 103 and HA 4 × GL 37 derived from parents contrasting for photoperiod sensitivity and growth habit. Results revealed monogenic control of photoperiodic response to flowering time; photoperiod sensitivity being dominant to insensitivity. Growth habit is controlled by three genes, GH1, GH2 and GH3 of which, one (GH1) is independent and the other two (GH2 and GH3) are complementary; indeterminacy being dominant to determinant growth habit. The genes controlling growth habit and photoperiodic response to flowering time were linked in coupling phase in these lines. Dolichos bean (Lablab purpureus L. Sweet) is commonly known as field bean, hyacinth bean, Indian bean, sem, butter bean, Egyptian kidney bean and lubia bean etc., belongs to the family Fabaceae and is one of the most ancient crops among the cultivated plants. In India, dolichos bean is primarily cultivated in Karnataka and adjoining districts of Tamil Nadu, Andhra Pradesh and Maharashtra (Mahadevu and Byregowda 2005) and used as vegetable (immature green soft pods and immature grains) and forage (NRC 2006). It is cultivated either as a pure crop or intercropped with finger millet, groundnut, castor, corn, pearl millet or sorghum. In Karnataka, dolichos bean is grown in an area of 85,000 hectares with a production of 30,000 tones and