Symbiotic Effectivity of Four Phaseolus vulgaris Genotypes after Inoculation with Different Strains of Rhizobium under Controlled Conditions

B ernhard Epping, A lexander P. H ansen, Bahm an Djalali and Peter M artin Institut für Pflanzenernährung (330), Universität Hohenheim, Fruwirthstraße 20, D-70593 Stuttgart, Bundesrepublik Deutschland Z. Naturforsch. 49c, 343-351 (1994); received February 4, 1994 Phaseolus vulgaris L., Plant x Bacterium Interaction, Rhizobium leguminosarum bv. phaseoli, Rhizobium tropici, Symbiotic Effectivity Four varieties of P. vulgaris L. were tested for their symbiotic nitrogen fixation effectivity in combination with nine different strains of Rhizobium leguminosarum bv. phaseoli and Rhizobium tropici. Plants were grown under controlled conditions and harvested 23 days after planting. Acetylene reducing activity, total N-content and dry weight of individual plant components were determined. Significant differences due to plant x bacterium interaction were assessed by ANOVA, especially for the total nodule mass per plant and the acetylene reducing activity per nodule dry weight. Data for acetylene reducing activity per plant corre­ lated highly with the corresponding data for the total N-content. The comparison of the total N-content in symbiotically grown plants, lacking supply of mineral N, with plants luxuriously supplied with mineral N (relative N-accumulation rate) revealed high values (between 60% and 70% of maximal N-uptake) for some symbiotically active plant/bacterium combinations for this early developmental stage of the symbiosis N2 fixation potential for such symbioses.