It is important to find methods, which may alleviate the adverse effect of stress on the growth of plants. Salinity is an important stress world wide, unfavorably affecting plant growth and crop production, Here we have presented a new method, which can efficiently alleviate salinity stress on the growth and nitrogen fixing ability of soybean and the associative N fixing bacteria, Bradyrhizobium japonicum. During the process of symbiotic N fixation between soybean and B. japonicum, the initial stages of the process, most importantly the exchange of signal molecules between the two, symbionts, are unfavorably affected by the stress. Accordingly, we hypothesized, tested and proved that if the bacteria is preincubated with the specific signal molecule, genistein, they are able to alleviate salinity stress on the growth and N fixing ability of soybean and B. japonicum. The book can be used by a wide range of audience including students, researches, academicians and scientists at the related disciplines, including plant biology, plant physiology, microbiology, biotechnology, molecular biology, environment, etc. Hoping that such a contribution can be used efficiently and widely.