Effect of rhizobial strains on nodulation and yield of Soyabean in smallholder areas of Zimbabwe

Abstract-A study was conducted in four districts of Zimbabwe of varying rainfall, temperature and soils. The objective of the study was to evaluate the interaction of selected rhizobial strains (MAR 1305, 1306, 1326, 1494, 1497 and 1515) and two soyabean varieties, a promiscuous and a specific one, on nodulation, grain and biomass yield. This study was carried out during the 2011/2012 and 2012/2013 seasons. The trials were laid out in a Randomized Complete Block Design (RCBD) with two factors (variety and strain) replicated three times. Both nodulation and yield responded significantly (p0.05) to rhizobial inoculation at all test sites. Strain MAR 1305 gave the highest yield in terms of both biomass (2.95 ton/ha) and grain (1.4 ton/ha). Results point to the need for matching soyabean varieties with rhizobium strains for given soils, rainfall patterns and temperature for economic yields. Also seed inoculation is essential for smallholder soyabean production in the soils investigated.