Growth and nodulation response of soybean (Glycine max L) to Bradyrhizobium inoculation and phosphorus levels under controlled condition in South Western Ethiopia

Abstract

The study was conducted to investigate growth and nodulation response of Clark 63-K soybean variety toBradyrhizobium japonicum inoculation and phosphorus levels under lath house condition at Jima Agricultural Research Center in 2010. The crop was evaluated in terms of nodule number, nodule volume, nodule dry weight, shoot nitrogen content, plant height, number of pod bearing branches, shoot dry matter and root dry matter. The result revealed that an interaction effect of the main factors did not significantly (P < 0.05) influence number of pod bearing branches, shoot dry matter and root dry matter yield of the crop. In terms of shoot nitrogen content and plant height, Clark 63-K soybean had no response to inoculation when it was grown without phosphorus. However, inoculation significantly (p < 0.05) increased these parameters over the uninoculated control when 60, 120 and 180 mg kg-1 phosphorus were applied. For uninoculated and inoculated treatments, phosphorus significantly (p < 0.05) influenced all nodulation and growth traits. The three phosphorus treatments (60, 120 and 180 mg kg-1) significantly (p < 0.05) improved pod bearing branches, shoot and root dry matter yield over the untreated control. Inoculation coupled with 120 mg kg-1 phosphorus level being considered an optimal combination for Clark 63-K soybean production in the area. Key words: Growth, nodulation, phosphorus, soybean.