Screening Of Superior Soybean Rhizobial Strains And Approach Of Application For Region Of HuangHuaiHai

Three hundred soybean rhizobial strains were collected from 11 regions of 3 provinces in region of HuangHuaiHai. Initial classification was conducted employing IGS and ERIC-PCR. More than twenty representative strains and seven control strains were selected according to the geographical location, types of molecular genetics of strains and the host species. Superior soybean (Glycine max) rhizobial strains were screened using vermiculite and soil two-step screening that match Fudou9765 and Zhonghuang13 and applied in soil pot experiment and plot experiment. Preliminary studies of its application were carried out and the results are as follows:Most strains from the screening by vermiculite pot promoted the nodulation and improved the dry weight of plant. The number of root nodule and dry weight were classified and combined using the method of QUARTILE. The total N of the plants that behaved well in both aspects were tested. B. japonicum 4302,B. japonicum 4321,S. fredii 4543,S. fredii 4822,S. fredii USDA205,B. japonicum 2178 behaved well in the nodule number and dry weight in the Fudou9765 experiment, and the total N were increased by 114.49%,113.04%,137.68%,126.09,115.94%,121.74% than the control respectively. S. fredii 4203,B. japonicum 4219,B. japonicum 4231,S. fredii 4644,S. fredii 4823,B. japonicum 2178 behaved well in the nodule number and dry weight in the Zhonghuang13 experiment, and the total N were increased by 95.50%,89.19%,91.89%,108.11%,109.91%,87.39% than the control respectively. The results demonstrated that these strains have a good match with the host plant and high efficiency in nitrogen fixation. The strains were screened by soil pot in the next step.The competitive capacity of the strains compared with indigenous rhizobium was investigated in the screening by soil pot. The rate of nodulation occupancy was tested by BOX-PCR finger-print method. The results of the experiment suggest: Six tested strains on Fudou9765 improveed the nodulation activity. The nodulation number, dry weight of plant and total N of B. japonicum 4302,S. fredii 4822 were increased by 55.64%,88.72%,30.60% and 39.15%,34.06%,29.10% respectively. The rate of nodulation occupancy reaches 30% which is significantly higher than other strains. Therefore, B. japonicum 4302 and S. fredii 4822 were selected as superior strains for Fudou9765. The nodulation number, dry weight of plant and total N of B. japonicum 4219,S. fredii 4823 in the six tested strains on Zhonghuang13 were increased by 53.64%,30.54%,19.60 and 66.89%,26.14%,10.92% respectively. The rate of nodulation occupancy reached 20% which is significantly higher than other strains. Consequently, B. japonicum 4219 and S. fredii 4823 were selected as superior strains for Zhonghuang13.The effect of the amount of different starter fertilizers, different inoculation methods, different types of nitrogen fertilizer, reduction in N fertilizer and trace element on the nodulation were determined on the plants inoculated by the screened strains in the further study. The results suggest: The starter fertilizers has less effect on the nodulation, but has a greater impact on the nitrogen fixation ability of root nodule. The root nodule inoculated with N0.06 (3 Kg/mu) played a significant role in nitrogen fixation. The seed dressing exhibited well in Anhui region, improved the rate of nodulation occupancy significantly and then promoted the effect of nitrogen fixation the yield. The experiment of different types of fertilizer illustrated that the difference in the effect of different types of fertilizers on the nitrogen fixation of nodulation is not significant. CON₂H₄ is a bit better than (NH₄)₂HPO₄. Trace element has little impact on the inoculated strains in Anhui region. The plot experiment of additional N fertilizer amount suggests that additional fertilizer has less impact on the yield when inoculated rhizobial. Inoculation promoted the yield as the common manure did.