Genotypic Differences in Symbiotic N2 Fixation of Some Alfalfa (Medicago sativa L.) Genotypes

Abstract

In a highly controlled laboratory experiment, four alfalfa ( Medicago sativa L.) cultivars were grown in all combinations with five strains of Sinorhizobium spp. with the aim to assess differences in nitrogen fixation among alfalfa genotypes and compatibility of symbionts. Based on shoot dry weight and total N content, it was noted that each cultivar showed a great compatibility with particular strains. Variety K-28 inoculated with all investigated strains exhibited the highest shoot dry matter, compared to other investigated cultivars. Using symbiotic N fixation, cultivar K-28 inoculated with L3Si strain gained high compatible association due to the 87% of shoot dry weight in relation to uninoculated control with full N content (100%). The significant coefficient of variation (CV%) for shoot dry matter of inoculated treatments was found (19.41–57.83%) depending on bacterial strain and plant genotype. Higher CV% values of inoculated plants compared to uninoculated plants indicated the influence of strain on increasing variability of the plants. As the effectiveness of the N 2 fixation varies widely in different rhizobia-host combinations, it would be possible to identify the highly effective rhizobial strains, which would represent commercial strains of microbiological fertilizers for particular cultivars.