Effect of Heterodera glycines on Yields of Nonnodulating Soybeans Grown at Various Nitrogen Levels.

Response of a nonnodulating soybean strain to infection by Heterodera glycines was greatly affected by applications of NaNO. Soybean yields from nematode infested microplots were reduced 71.8, 44.4, and 10.7% at low, medium, and high N levels, respectively, when compared with yields of noninfested plots at similar N levels. The results indicate that besides reducing root nodulation and N fixation, H. glycines causes soybean yield reductions by inciting deleterious host responses that increase with N deficiency.