Overcoming the Stressful Effects of Salinity and Acidity on Soybean Nodulation and Yields Using Signal Molecule Genistein Under Field Conditions

Soil stresses such as salinity and acidity may adversely affect nitrogen (N)₂-fixation. The hypothesis of this study is that soil salinity and acidity inhibit soybean Glycine max (L.) Merr.] nodulation and N₂-fixation due to, at least in part, disruption of the signal exchange process. The objectives were: 1) to determine the effects of stressful soil salinity and acidity on the signal exchange processes between soybean and Bradyrhizobium japonicum, and 2) to determine whether or not the addition of signal molecule genistein to B. japonicum can overcome at least part of the inhibition of nodulation, caused by stressful soil salinity and acidity. Salt (sodium chloride) and sulfur (S) were applied. Genistein (0, 5, and 20μ M) was tested. Genistein addition could partially overcome the salt and acidity stresses by increasing soybean yields up to 21% and 23%, respectively. These novel findings may be very useful for planting soybean under salinity and acidity stresses.