Interactions of Seleted Glycine soja Sieb. & Zucc. Genetypes with Fast‐ and Slow‐Growing Soybean Rhizobia1

Abstract

Seven genotypes of Glycine soja Sieb. & Zucc. (wild soybean) weree xaminedfo r effectiveness of N2‐fixing symbiosesw ith fastand slow‐growing soybean rhizobia. Some genotypes were identlfied whichd emonstrated ifferential effectiveness with the two rhlzobia groups, while other lines had no apparent preference. Two genotypes with opposite preferences were tested with six strains of each rhizobia group. Glycine soja PI 342434 formed very effective symbioses with the slow growers, fixing over three times as much N with this group of strains as with the fastgrowing strains. Conversely, PI 468397 formed the most effective symbioses with the fast growers, fixing about three times as much N as with the slow growers. The demonstration of greater symbiotic effectiveness with the fast‐growing rather than the slowgrowing rhizobia has not previously been reported in Glycine species. PI 468397 was the genotype from which one of the fastgrowings trains was originally isolated. Thus, differential rhizobia group (fast or slow) interactions found in G. soja genotypes indicate that G. soja possesses a greater diversity of reaction to the two rhizobia groups for this characteristic than common North American G. max genotypes.