Genetic variability for phytic acid phosphorus and inorganic phosphorus in seeds of soybeans in maturity groups V, VI, and VII

Abstract

Phytic acid (PA; myo-inositol 1,2,3,4,5,6 hexakisphosphate) in soybean [Glycine max (L.) merr.] meal is a major source of P in animal excreta, a serious environmental pollutant. Genetic mutants in which seed PA is reduced by 60% have been developed. The objectives were to assess (i) natural variation in seed PA-P and inorganic phosphorus (Pi) concentrations in soybean breeding lines and cultivars of Maturity Groups (MGs) V, VI, and VII; (ii) genotype X environment (G X E) interactions for Pi and PA-P, and (iii) relations among PA-P, Pi, and seed protein concentrations. Three sets of cultivars and breeding lines were tested separately in two or three environments. Variation among lines was highly significant, ranging from 3.77 to 5.07 g kg-1 PA-P and from 0.19 to 0.37 g kg-1 Pi. The G X E interactions were highly significant for Pi concentration, but significant variation for PA-P concentration was observed only among cultivars, not across environments nor as G X E interactions. Rank correlation coefficients for Pi concentrations between environments were large (0.65-0.88), suggesting that the G X E interactions were due to differences in average Pi concentration in various environments. Variation in seed protein was highly significant in all three sets, but protein was not correlated with PA-P and was correlated with Pi (r = 0.56) only in the MG V breeding lines test. Therefore, generic relationships between protein and either PA-P or Pi could not he established. Significant natural genetic variation indicates that PA level of potential adapted parents may be useful in breeding low-PA soybeans. © Crop Science Society of America.