Synopsis In soils free of soybean rhizobia, some strains of Rhizobium japonicum were more effective than others on Lee soybeans. In rhizobia‐contaminated soil, none of the strains caused any detectable growth responses on seed‐inoculated plants.

Sypnosis The degree of susceptibility of 40 varieties of the soybean (Glycine max L.) to a bacterial‐induced chlorosis is reported. Ten varieties showed no chlorosis when given selected inoculants in greenhouse tests; 7 others proved to be negligibly susceptible; 11 varieties showed a light or variable susceptibility; 6 were moderately susceptible; and 6 were highly susceptible. The results are discussed in relation to nodulation and symbiotic nitrogen fixation and yield.

Competition between genotypes of Rhizobium japonicum was studied by using chlorosis‐inducing strains 76 and 94 to facilitate identification of strains recovered from the nodules of soybean plants. Chlorosis‐inducing strains were individually mixed in varying proportions with each of nine normal strains and the mixtures were used as inoculants on the Hawkeye and Lee varieties. The plants were cultured in the greenhouse under conditions previously described. Technique studies indicated that with rare exceptions a single nodule contained only one bacterial strain and that chlorosis of sorghum seedlings produced by a water extract of a nodule was a reliable indication that the nodule contained a chlorosis‐inducing strain. Strain 76 had a pronounced competitive advantage over all normal strains regardless of the proportions of the strain in the mixtures. As little as 1.1% of strain 76 in the mixture with strain 38 caused 85% of the nodules. Strains 31 and 71 were more competitive against strain 76 than were the other normal strains. Chlorosis‐inducing strain 94 was much less competitive against 8 of the 9 normal strains than was strain 76. The extent of chlorosis of the soybean plants gave a rough estimate of the competitive relationships between strains. The varieties Hawkeye and Lee were essentially identical in response to the various mixtures.

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A RICULTURAL Experiment Station workers in the United States are interested in the pasture and forage potentialities of Lotus corniculatus L. (birdsfoot trefoil) and Lotus uliginosus Schkuhr (big trefoil). Since the growth habits of these two species are quite different they naturally respond to different soil and climatic conditions. The broad-leafed type, L. corniculatus var. arvensis Ser., finds wider use in the midwestern and northeastern states, whereas the narrow-leafed type, L. corniculatus var. tenuijolius L., is generally grown in Oregon