Genetic and Environmental Variation of Seed Yield and Yield Components in African Yam Bean (Sphenostylis stenocarpa (Hochst. Ex. A. Rich.))

Abstract

Fourteen genotypes of African Yam Bean were grown in three locations Abakaliki, Enugu and Ibadan in 2012 planting season and were analysed for genotype, environment and genotype × environment variability in yield and yield components. There was significant environmental as well as genetic effect on parameters measured. Genetic effect accounted more for the variability observed in 100 seeds weight (61%) and pod width (56%),  but  less effect on seed per pod (34%), pod length (40%), peduncle per plant (22%), pod per peduncle (17%), peduncle with pod (36%), peduncle without pod (37%), pods per plant (33%) and seeds per plant (29%). Genotype also largely accounted for variability noticed in days to 50% flowering (50%). G × E interaction significantly affected all the yield components except number of seeds per plant. Ibadan location had good textural and structural characteristics (pH = 6.13, organic matter = 2.88, k = 0.73, p = 8.89, % N = 0.68) than the other locations; Abakaliki (pH = 6.54, organic matter = 1.16, k = 0.32, p = 4.88, % N = 0.09) and Enugu (pH = 6.29, organic matter = 1.48, k = 0.37, p = 5.21, % N = 0.11). Abakaliki and Enugu showed highest maximum temperature, lowest minimum temperature, highest rainfall but lower relative humidity than Ibadan. Ibadan location performed averagely higher for all the parameters measured. The correlation coefficient from the three locations indicated relationship among the parameters. The GGEbiplot result showed that most genotypes are more adapted to Ibadan site while Abakaliki and Enugu similar in adaptation. Hence, AYB adaptation is dependent on genotype, environment and G × E interaction.

Keywords: Sphenostylis stenocarpa; genotype, environment, yield component, interaction, yield