Isolation?Indentification And Application Of Elite Soybean Rhizobia Strains

Elite rhizobia inoculant can provide nitrogen nutrition for the legume crop by symbiotic nitrogen fixing.The application of rhizobia inoculant can not only increase the yield of legume crop,it also replace a part of chemical nitrogen fertilizer and keep soil in nature condition.In China,there are some problems in the rhizobia inoculant application on soybean planting.In this study,we test the symbiosis efficiency of some rhizobia strains inoculated on some soybean cultivars from different area in China.We also study the application of inoculant in soybean farmland.Experimental experience from this study were hoped to improve the rhizobia inoculant application in soybean planting.Firstly,six fast-growing soybean rhizobia strains and two slow-growing soybean rhizobia strains were selected for matching experiments between rhizobia and 27 soybean cultivars from different area in China.The data of sand pot experiment showed that: all the 6 fast-growing soybean rhizobia strains can nodulate on 24 soybean cultivars.The plant biomass of soybean inoculated with rhizobia was significantly increased than that of non-inoculated soybean.Among them,the rhizobia strains HN01,GR3,HH29 and HH103 demonstrated high nitrogen fixation efficiency no less than that of USDA110,they have potential merit to be applied in North-east China,Valley of the Yellow and Huaihe Rives,Valley of the Yangze River,and South-east China.The soybean varieties Zhongdou 39,BD2 and Tianlong 1 showed higher biomass when inoculated with eight tested rhizobia respectively.The outstanding rhizobia-soybean pair are:GR3+Zhongdou ? HN01+Liaodou 14 ? HN01+Xudou14 ? HN01+BD2.These rhizobia-soybean pairs are fit for Valley of the Yangze River?Northeast China?Valley of the Yellow and Huaihe Rives?Southeast China respectively.The pot data of Hebei soil shown that: HN01 can significantly increase the shoot biomass of Jidou17 and its nodule nitrogenase activity by 40.8% and 65.8% respectively;Nodule occupancy of HN01 in Hebei soil pot account for 81.86%.Compare with indigenous rhizobia in Hebei soil,HN01 shown high competitive ability.Secondly,some indigenous rhizobia were isolated from soil and their symbiosis efficiency were tested.More than fifty rhizobia strains were isolated from 10 soil samples from Heilongjiang,Hebei and Hunan provinces.Thirty-six of them were identified to be Bradyrhizobium japonicum by BTB color reaction and 16 SrDNA analysis.From them,four stains with better symbiosis and nitrogen fixing ability on soybean from Heilongjiang Province were screened by sand and soil pot experiment successively.Sand pot test showed that: the strains SN2-5,NW5-3,SN7-2 and SN10-3 could effectivelynodulate on seventeen soybeans cultivars from Heilongjiang Province,and the nitrogenase activity in nodule and biomass of soybean were significantly increased than those of the negative control.Their symbiosis efficiency are better than HN01 and USDA110.The strains NW5-3,SN10-3,SN7-2 also shown strong symbiosis efficiency on soybean Heinong61 planted in black soil from Heilongjiang Province.Under 10 mM NH4NO3 stress,the strains SN2-5,NW5-3,SN7-2 and SN10-3 can still nodulate on soybean Heinong61.Compare with the nodules without nitrogen stress,the nodules formed by NW5-3 and SN10-3 under NH4NO3 stress still remained 50% nitrogenase activity.The best matching performance under NH4NO3 stress is SN10-3+ Heinong61.Base on greenhouse experiment,the field plot experiment were carried out in Shijiazhuang Hebei and Haerbin Heilongjiang Province.Solid and liquid inoculants containing HN01 and USDA110 were made for field plot.The result indicated that:Under the full-conventional fertilization condition,the solid rhizobia inoculant increased the yield of Jidou 12?Heilong61?Longha10-4139 by 11.33%?19.5%?7.1% respectively;and the liquid rhizobia inoculant increased the yield of Jidou12?Jidou17 by 6.52%?8.27%respectively.Under the half-conventional fertilization condition,the solid inoculant increased the yield of Jidou17 by 4.68 %.Under the condition of no-conventional fertilization,solid inoculant increased the yield of Longha10-4139 by 20.3 %;liquid inoculant increased the yield of Jidou17 by 20.3 %.Two inoculants could promote soybean nodulation,growth and yield in different degree.At last,the symbiosis efficiency of co-inoculation with rhizobia and PGPR was tested in this study.The Bacillus sp strains HZP1?HZK1 was identified to have the abilities of dissolving phosphorus and nitrogen fixing.The nodulation and biomass of Astragalus sinicus planted in soil pot were improved by co-inoculated with Mesorhizobium huakuii 7653 R and Bacillus sp HZP1.The test data shown that: HZP1 had potenial application value.By this study,the compatibility between rhizobia strains and soybean cultivars in this study were preliminarily identified.The potential application value of three PGPR were also evaluated.It would provide some guidance for the field application of these soybean rhizobia.