NODULATION, NITROGEN FIXATION AND YIELD POTENTIAL OF COMMON BEAN (Phaseolus vulgaris L.) VARIETIES UNDER SHADE

Abstract

Common bean (Phaseolus vulgaris L.) is a herbaceous annual crop which in a symbiotic relationship with specific soil bacteria, ‘fixes’ atmospheric nitrogen (N 2 ) into amino form that can be used for plant growth.A field experiment was conducted to determine the effect of shade and Rhizobium inoculation on nitrogen fixation, nodulation, yield and yield components of three common bean varieties at Hawassa University Research Farm, Hawassa Southern Ethiopia. The experimental treatments consisted of a factorial combination of 2 levels of shade (25% shading and non-shading), 2 levels of inoculation (inoculated and non-inoculated) and three common bean varieties (HawassaDume, Nasir and Ibbado). The experiment was laid out as a randomized complete block design with four replications. The result showed that inoculation of common bean with Rhizobium strain HB-429 significantly affected all parameters compared to the non-inoculated plants in the field trial. The interactions of variety,shade and inoculation affects leaf area, leaf area index, specific leaf area,grain yield and 100 seed weight of common bean. The highest nodule number was recorded from rhizobium inoculated plots, while the lowest nodule number was recorded from the 25% shade treatments. Similarly the highest grain yield was recorded from inoculated Hawassa dume variety of open treatments while the lowest grain yield was recorded from non-inoculated Ibbado variety at 25% shade treatments.Also this study indicated inoculated Hawassa dume variety from the open treatments derived the greatest percentage of N from N 2 fixation and the lowest percentage of N was derived from non-inoculated Ibbado variety from the 25% shade treatments N uptake of common bean grown on full light had significantly greater N content than wheat this increase in N uptake of common bean is presumably derived from N2-fixation capacity of the legumes. Therefore, variety Hawassa dume inoculated with rhizobium strain HB-429 in open generated the highest seed yield. It would be worthwhile to do similar experiments on the area with the inclusion of more shade levels to refine the findings