Combining ability for days to flowering and grain yield among cowpea (Vigna unguiculata) of different maturity periods

Abstract

Combining ability studies was conducted on ten parental lines of cowpea with varied maturity periods. Complete diallel mating were made to generate 45crosses, 45 reciprocals and their parents, making a total of 100 entries which were evaluated in to two locations (Teaching and Research Farm, Ekiti State University, Ado Ekiti and College of Education Demonstration Secondary School Farm, Ikere-Ekiti, during the 2010 and 2011 cropping seasons using Randomized Complete Block Design with three replications. Data were obtained on plant height, days to 50% flowering, first day to maturity, numbers of pods per plant, weight of 100 seeds (g), grain yield kgha^-1 and mid-parent heterosis at harvest were obtained. Result showed that there were significant differences among the entries (p<0.05) for all traits studied. The mean value for days to first flowering varied from 42.47 to 45.23 days, days to 50% flowering ranged between 50.07 and 51.73 days, days to pod maturity varied from 58.77 to 64.24 days. The mean value of the hybrid lines exhibited the earliest flowering and pod maturity traits among the entries. The reciprocal crosses had the highest mean values for weight of 100 seeds which weighed 17.55g. The reciprocal cross P₇ × P₄ had the highest grain yield of 6069.43kgha^-1.The average grain yield value ranged from 1259.88 to 3896.66 kgha^-1.General combining Ability (GCA) for most of the traits are significant except flowering interval. Only days to pod maturity are not significant for specific combining Ability (SCA) among the traits. P₁, P₄, P₅ and P₆ are identified to be the best general combiners for most of the characters. Crosses involving P₁ x P₄, P₁ x P₆, P₄ x P₂ and P₉ x P₅ were identified to be excellent specific combiners for cowpea grain yield and earliness traits. Cross combinations P₂ x P₄ and P₄ x P₂ had reciprocal effect. The mean of the crosses and reciprocal for mid-parents heterosis (%) was high (280.47%) among the crosses. The ratio of GCA to SCA ranged from less than 1 for flowering intervals to 48 for days to 50% flowering, this underscores the importance of additive effect, suggesting that reasonable progress can be achieved using selection procedure

Keywords: Vigna unguiculata, diallel, combining ability, SCA, GCA, heterosis