Symbiotic properties of soybean rhizobia isolated from soils of the Nigerian Sudan Savanna

Abstract

Soybean is one of the most important legume crops that form symbiosis with native rhizobia (Zhang et al., 2011). The distribution, abundance and nitrogen-fixing efficiency of soybean rhizobia are strongly related to genotypes or cultivars of soybeans (Saeki et al., 2008). Many soils contain native rhizobia while at other times, desired rhizobia strains can be indirectly introduced as inoculants to the soil or plants to add nitrogen from the atmosphere to the soil in order to improve soil fertility. Response to such inoculations are often times challenged by host-strain limitations. Hence the need to screen native rhizobia on the basis of effective symbiosis for use in inoculation program . The objectives are to: 1. assess growth and nodulation characteristics of specific soybean varieties 2. quantify the amount of nitrogen fixed through their symbiotic effectiveness ( percent)