Maternal and Cytoplasmic Effects on Seed Protein Content in Soybeans, <i>Glycine max</i> (L.) Merrill¹

Abstract

Protein contents (in percent) of individual soybean, Glycine max (L.) Merrill, seeds from F 1 , F 2 , backcross and parental populations associated with crosses between high and low protein lines were estimated by analyzing small pieces of cotyledons by the micro‐Kjeldahl method. Mean percent protein of F 1 seeds did not differ from that of selfed seeds produced on the same plants indicating strong maternal effects. Overall means of F 2 and backcross seeds obtained from two pairs of reciprocal crosses differed significantly in percent protein indicating cytoplasmic effects with a 3 to 4% increase being associated with cytoplasms from the high protein lines. Variances of selfed seeds on plants of both high and low protein parental lines were as large as variances of selfed seeds on F 1 plants from crosses between these lines. Our results suggest that the genotype of a soybean seed has little influence on percent protein of the seed. Thus selection among individual seeds from a single plant to increase protein percent is probably ineffective in soybeans.