Weathering of soya bean [Glycine max (L.) Merr.] in the tropics, as affected by seed characteristics and reproductive development

Abstract

Small seed size, hard seed coat, and reduced interval from the R6 to R7 reproductive developmental stage are factors associated with resistance of soya bean [Glycine max (L.) Merr.] seed to field weathering. A study was conducted to evaluate the role of these characteristics on germination of 25 genotypes after exposure to field, incubator, and sprinkler-weathering treatments. At physiological and harvest maturity, and after both simulated weathering treatments, germination was negatively correlated with 100-seed weight and the number of days from R6 to R7. Only under the disease pressure of the incubator treatment was hard seed coat significantly correlated with germination (r = 0.48). Coloured seed was superior to yellow seed except for large-sized coloured seeds. Small-seeded genotypes had higher germination than large-seeded types, particularly when they matured late or had a short interval from R6 to R7. One genotype, OCB, matured early, had relatively large seeds, and few hard seeds, yet had good seed quality, possibly attributed to a short interval from R6 to R7. The incubator test was the least useful weathering treatment.