Genetic Variation for Green Pod Yield and Quality Among Vegetable Soybean Genotypes

Abstract

Few studies have evaluated vegetable soybean (Glycine max [L]. Merr.) for green pod yield and individual and total sugar when harvested at green pod stage (R6 to R7). The purpose of this research was to assess the amount of genetic variation that existed among vegetable soybeans for green pod yield (GPY), hundred pod weight (HPW), pod length (PL), plant height (PH), and individual sugars (glucose, fructose, sucrose, raffinose, and stachyose) and total sugar, and to determine the association of GPY with the individual and total sugars. Thirty-one vegetable soybean genotypes from maturity groups (MGs) III, IV, V, and VI were planted at Virginia State University Research Farm during 1996,1997, and 1998. Each genotype was harvested at green pod stage. There was substantial genetic variation for GPY, PH, and PL as indicated by relatively large genotypic variance components. Heritability (h2) estimates of 0.85, 0.68, 0.81, and 0.85 were observed for GPY, HPW, PL, and PH, respectively. These high h2 estimates imply that selection for improved GPY along with PL and HPW can be achieved in a breeding population. Correlation values of HPW with sucrose and total sugar content were 0.598 and 0.447, respectively. Pod length had correlations of 0.598 and 0.447 with sucrose and total sugar, respectively. The PL was positively correlated (0.766) with HPW. The PL σ2 g variance was 22 times larger than σ2 gy variance, suggesting that selection for PL should be effective. Because pod length reaches the maximum size 30 days after flowering, it could be used an indirect selection criterion to identify genotypes with high sucrose and total sugar contents.