GROWTH, SYMBIOTIC AND YIELD PERFORMANCE OF SOYBEAN (Glycine max L.) VARIETIES IN RESPONSE TO Bradyrhizobium INOCULATION AND PHOSPHORUS APPLICATION AT ASSOSA, WESTERN ETHIOPIA

Abstract

This research was conducted during 2016 main cropping season on field at Assosa, in Benishangul Gumuz Regional State with the objectives of investigating growth, symbiotic and yield performance of three soybean (Glycine max L.) varieties in response to Bradyrhizobium inoculation and P fertilizer application. The treatments studied included three P levels (0, 10 and 20 kg P ha -1 ), two inoculation levels (uninoculated and inoculated with Bradrhizobium strain; MAR-1495) and three soybean varieties (Gizo,Belessa-95 and Local) in randomized complete block design with factorial arrangement using three replications. The results revealed that Bradyrhizobium inoculation with MAR-1495 significantly (P<0.01) increased most of the parameters studied as compared to the control. Inoculation with strain MAR-1495 significantly (P < 0.01) increased nodule number, nodule dry weight, shoot dry weight, root dry weight, leaf area, grain yield, and above ground total biomass as compared to the control. Application of P at 20 and10 kg ha -1 significantly increased nodule number, nodule dry weight, and root dry weight, shoot dry weight, leaf area, above ground total biomass and grain yield. There was significantly (P < 0.01) cultivars effect for most of studied parameters; Belessa-95 variety had better responded on nodule number, nodule dry weigh, grain yield and above ground total biomass as compared to Gizo and Local varieties. The highest grain yield was recorded from Belessa-95 variety 3.29 ton ha -1 from combined application of 20 kg P and Bradyrhizobium inoculation. Nodule number plant -1 was positively and significantly correlated with most of growth parameters, yield and yield components. It could, thus, be deduced that use of MAR-1495 Bradyrhizobium strain and Belessa-95 variety with application of 20 kg P markedly increased the productivity of the crop at Assosa area, however economic analysis revealed that the highest net return was obtained from application of 10 kg P and Bradyrhizobium inoculation with strain MAR-1495. The use of MAR-1495 strain and Belessa-95 variety with application P at 10 kg ha -1 could be recommended, but verification of the results on different farmers’ field could be required before wide use of this study.