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Trifolium (Trifolium L.) is an important class of forage. Xining region clover rhizobia (Rhizobium leguminosarum var.trifolii) conduct research to find energy efficient nitrogen-fixing rhizobia inoculant developed can be widely applied to further improve the yield of clover Xining region basis. In this study, collected from different regions of Xining nodule, Rhizobium strains isolated from nine through tieback early screening test compared to three traits excellent strains are numbered NY6-1, NY6-2 and BY5-2 strains by rescreening Selected NY6-1 as bacteria, agents conducted research. To filter to strain as a starting strain of Rhizobium clover biological characteristics and effects of symbiotic nitrogen fixation. Race interconnected tests showed that clover rhizobia may have race-specific, can not make soybean, alfalfa, clover genus peanut non-nodulation. Separating the resulting strain YMA plate 3 by 25 ℃ for 48h, 1-3mm grow into single colonies, colonies were round, white or translucent, smooth, slightly raised, neat edge, sticky, wax-like gloss; grown in culture medium does not produce biofilm, 48h static culture will produce some smoke-like precipitate disappears after shaking. Gram-negative bacteria Rhizobium display clover, clover rhizobia flagella staining showed a single flagellum raw side. Beef extract - peptone medium, no growth, BTB acid reaction, negative gelatin liquefaction, starch hydrolysis is not 3 - keto-lactose test was negative, citrate utilization test is negative, oxygen tests showed nodules bacteria are aerobic, acid tests showed that rhizobia produce a good at a pH of 5-8, with a certain acid and alkali resistance. Small nodules, showing staghorn or granular. Clover rhizobia are fast-growing rhizobia. According to morphological and physiological and biochemical characteristics, NY6-1, NY6-1 and BY5-2 strain was identified as R. leguminosarum clover biotypes (Rhizobium leguminosarum var.trifolii). Medium optimization tests showed that the optimum medium ratio of glucose (C 6 H 12 O 6 ) 15g, sodium chloride (NaCl ) 0.1g, dipotassium hydrogen phosphate (K 2 HPO 4 ) 0.5g, magnesium sulfate (MgSO 4 · 7H 2 < / sub> O) 0.6g, yeast extract 0.4 g, calcium chloride (CaCl 2 ) 0.05g, Rh trace element solution 4ml; optimum fermentation conditions were inoculated 1.5%, fermentation temperature 25 ℃, medium initial pH 7.5, incubation time 32h. Agents used for pot experiment showed that the preparation of the four agents on the impact of clover are highly significant difference (P lt; 0.01), agents B (garden soil: ash = 7:3) promoting effects best , followed by the agents A (garden soil: ash = 1:0) and agents D (vermiculite).
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