Heterosis and inbreeding depression studies in urdbean [Vigna mungo (L.) Hepper]

An investigation was conducted to study the extent of heterosis over mid parent, better parent (heterobeltiosis), and parent (NDU1) as well as inbreeding depression in F₂ generation. Eight genotypes were used to produce six crosses viz.; NDU 97–10 × IPU 981(cross I), NDU 99-2 × IPU 981 (cross II), Shekhar 1 × KU 300 (cross III), Shekhar 1 × KU 300 (cross IV), Uttara × NDU 1 (cross V) and Uttara × KU 321 (cross VI) and their F₂ populations. These populations were laid out in Compact Family Block Design with three replications at Genetics and Plant Breeding Research Farm, N.D. University of Agriculture and Technology, Kumarganj, Faizabad (U.P.) during Zaid and Kharif 2008. Positive and highly significant standard heterosis (%) for seed yield per plant was registered in all the six crosses. Most heterotic crosses for yield were cross II (37.52), cross VI (26.48), cross IV (24.95) during Zaid and cross V (55.31), cross II (53.22), cross I (35.85), cross VI (35.05) in Kharif. All these crosses also registered highly significant inbreeding depression for yield during both crop seasons. Negative and significant standard heterosis, heterobeltiosis, mid parent heterosis and inbreeding depression were recorded for days to 50 per cent flowering (cross I and III) and days to maturity (cross I, III and IV) in Zaid and days to 50 per cent flowering (cross V and VI) and days to maturity (cross I, III, V and VI) during Kharif.