Screening of high efficient symbiotic rhizobium for Medicago sativa cv. Gannong No.3 and M. sativa cv. Longdong

Using a combination of greenhouse pot and field experiments, this study determined the effect of inoculation with different rhizobial strains on seedling growth and nodulation capacity of two cultivars of Medicago sativa. Further, seedling photosynthetic characteristics and biomass components of M. sativa cv. Longdong were analyzed. The results showed that seedling biomass, plant height, number of branches and number of leaves of M. sativa cv. Gannong No.3 increased by 102%, 100%, 17% and 102%, respectively, after inoculation with 17767 strains in greenhouse; while Longdong inoculated with 17625 strains increased seedling biomass, plant height, number of branches and number of leaves by 187%, 48%, 80% and 47%, respectively. In the field condition, seedling biomass and plant height of M. sativa cv. Gannong No.3 was increased by 21% and 13%, respectively after inoculation with 17650 strains; while Longdong cultivar inoculated 17574 strains increased seedling biomass and plant height by 348% and 70%, respectively. Inoculated 6-3, 17537, 129, 17670, 17582, 17578 and 17650 strains treatments increased plant water use efficiency to some extent in Longdong cultivar, whereas seedling photosynthetic rate was increased only by inoculating 17578 and 17582 strains. Based on their performance in the greenhouse and field condition, the optimal symbiotic rhizobial strains with M. sativa cv. Gannong No.3 and M. sativa cv. Longdong was B2 and 17650, respectively.