Agronomic traits and genetic parameters in vegetable soybean evaluated in Puerto Rico

Abstract

In tropical regions of the Western Hemisphere, consumption of high-protein soybean [Glycine max (L.) Merr.] could improve the human diet. It would be necessary however, to develop adapted cultivars of appropriate seed size. The objectives of this study were to estimate heritabitity and phenotypic and genotypic correlations of agronomic traits, and to compare agronomic and reproductive traits of soybeans grown at different planting dates in Puerto Rico. Eighty-nine F_4:5  individual plants from the cross of IAC-8 [Maturity Group (MG) IX, not adapted for human consumption, and intermediate seed size] x Kanto-101 (MG IX, large-seeded cultivar developed for human consumption), the parents, and checks were planted in December 1992.  F_4:5 lines were evaluated in replicated tests in June and August 1993. Dates of full bloom (R2), of full seed (R6), and of full maturity (R8), plant height, pod width, and 100-seed weight were recorded. On an entry-mean basis, neritability values of all traits were moderately high (0.56) to high (0.96). Phenotypic and genotypic correlations ranged from zero to high (0.96). Rank correlations were moderately high, positive and significant, ranging from 0.41 to 0.79. In general for all traits, genotypes selected in the top 10% in the plantings of June and August, on the basis of entry means, would also have been selected as individual plants in the December planting. These results suggest that in the tropics genotypes may be selected in different planting seasons within the year, initially on the basis of individual plant performance, and later in replicated experiments.