Consortium Effect Of Rhizobium Strains To Regulate Physiological And Biochemical Response In Common Bean (Phaseolus Vulgaris) During Water Stress

Abstract

Common bean (Phaseolus vulgaris L.) is one of the important legume crop grown throughout the world as main dietary source of nutrient. It also plays a major role in soil fertility through biological nitrogen fixation. The major abiotic stress affecting common beans are drought stress and water stress, which cause the loss of productivity in Ethiopia and other countries. The aim of this study was to minimize the impact of water stress on common bean by using consortium effect of Rhizobium strains of Haricot Bean-429 (HB-429) and Haricot Bean of Ethiopia Agricultural legume-429 (HBEAL-429). This synergism acts as plant growth promoting rhizobacteria and expected to reduce the effect of water deficit and improve the yield. The study was carried out by using two contrasting drought tolerant (Awash-2) and drought susceptible (Nasir) common bean cultivars treated with the inoculants under greenhouse condition. Two soil water contents (80% and 40% of field capacity) for growth, physiological and biochemical adjusts were evaluated along with HB429 or HBEAL-429 strain alone, co-inoculation of HB-429 and HBEAL-429 strains and uninoculated seeds were grown in greenhouse condition. The experiments in greenhouse showed that co-inoculation has alleviated the plants situation under drought stress than Rhizobium strain alone and uninoculated control plants. Co-inoculation had significantly enhanced fresh and dry weight of leaves, fresh root and shoot (p<0.05). Then, the relative water content, fresh and dry weight of leave, root nodules number as well as proline content and chlorophyll a and b content were significantly affected (P< 0.05) in both varieties while a non-significant difference was observed at root nodule and root dry weight. Hence, positive effect through co-inoculation was observed in Awash-2 than in Nasir bean varieties. The present study showed that synergistic application had improved the potential to confer drought tolerance in common bean by changing various growth, physiological and biochemical parameters under drought stress conditions.