Nodulation of Stylosanthes guyanensis: prediction of Rhizobium effectiveness response with seed isozyme patterns

Abstract

Forty-nine introductions of S. guyanensis were tested against 22 strains of Rhizobium for effectiveness of the symbiosis in nitrogen fixation. A wide range of effectiveness between strains on individual accessions, and significant strain x accession interactions, were obtained. Two major groups of accessions were obtained on pattern analysis, a wide effectiveness response group with an average of 42% strains effective (containing 30 accessions) and a narrow response group with only 6% strains effective (19 accessions).

The seed isozyme patterns (esterase and acid phosphatase) were also determined on the 49 introductions. Classification of these data also revealed two major groups containing 28 and 21 accessions which corresponded on a broad basis with the accessions containcd in Lhc wide and narrow effectiveness response groups respectively.

The use of seed isozyme analysis as a guide to Rhizobium effectiveness response is proposed as a rapid screening technique for introductions of S. guyanensis.