RELATIONSHIPS BETWEEN NUCLEAR-DNA CONTENT AND SEED AND LEAF SIZE IN SOYBEAN

A correlation between genome size and agronomically important traits h as been observed in many plant species. The goal of the present resear ch was to determine the relationship between genome size, seed size, a nd leaf width and length in soybean [Glycine mas (L.) Merr.] Twelve so ybean strains, representing three distinct seed size groups, were anal yzed. Flow cytometry was used to estimate their 2C nuclear DNA content s. Data on seed size and leaf size of the 12 strains were obtained fro m 1994 and 1995 field experiments. Variation of 2C nuclear DNA among t he 12 soybean strains was 4.6%, ranging from 2.37 pg for a small-seed strain to 2.48 pg for a large-seed strain. Strain seed size was positi vely associated with leaf width (r = 0.92) and leaf length (r = 0.93). Genome size was highly correlated with seed size (r = 0.97), leaf wid th (r = 0.92), and leaf length (r = 0.93). The results of our study in dicate that there is a significant correlation between genome size and leaf and seed size in soybean. It is possible that selection for grea ter seed size either leads to, or results from, greater genome size. I f so, this relationship might be worth exploring at a more fundamental level.