Contrasting accumulations of calcium and magnesium in seed coats and embryos of common bean and soybean

How plant genotypes affect accumulation and within-seed distribution of Ca and Mg in soybean (Glycine max L.) and common bean (Phaseolus vulgaris L.) seed is important because of concerns in regards to human nutrition. Accumulation of seed Ca and Mg in separate experiments, each with 12 genotypes, was studied. Genotype affected seed Mg concentration [Mg] and especially seed Ca concentration [Ca] in the two species. Percentages of total seed Ca in seed coats ranged from 67% to 81% for the common bean genotypes and from 17% to 27% for the soybean genotypes. Percentages of total seed Mg in the seed coats ranged from 16% to 28% for the common bean genotypes and from 6% to 10% for the soybean genotypes. Percentages of seed dry matter in the seed coats were 9.3–11.0% for the common bean genotypes and 7.0–12.4% for the soybean genotypes. Four common bean and two soybean genotypes were next grown under similar environmental conditions in a greenhouse experiment. Results confirmed that seed coats of common bean are enriched in Mg and especially Ca relative to dry-matter distribution. In contrast, seed coats of soybean are enriched in Ca, but to a lesser extent than in common bean, and are not enriched in Mg.