Study On The Screening Of High-Efficient Sinorhizobium Meliloti For Medicago Sativa L. Cultivars And The Identification In Field

Alfalfa industry expand rapidly in China to meet the demand of modulating agricultural structure recently. The experience of legume production in the world indicated that inoculating rhizobia for legume was a key technique to increase its yield and improve its quality. This paper included investigating the indigenous inoculating alfalfa rhizobia in different soil and under different crops, selecting high effective strains for alfalfa utilizing different soil and testing the response to the inoculation of selecting strains in the field. Applying the technique of molecule biology to study the nodule occupy in the field. Establish a model for screening high effictive strains for alfalfa. The main results as follows:1. The number of indigenous rhizobia symbiant with alfalfa in the field is an important factor affecting the effect of inoculation. In the different soil type, in the same type soil under different crops and the same crop under different soil type, we test the indigenous rhizobia nodulating alfalfa and concluded that the indigenous number at low level in all testing area. Number of indigenous alfalfa rhizobia was 30-250 per g-1 dry soil in different crops in south of Jiangsu hilly areas, and 2.5+103-4.5+105 per g-1 dry soil in Loess Plateau. Indigenous number in Tongliao inner Mongolian and Huanghuaihai plain was 40-3000 size per g-1 dry soil except Wuqiao county. It is very important to inoculate high effective Sinorhizobium meliloti strains when plant alfalfa.2. Taking the Zhongmu No. 1, Rs, Vector, and WL323 as cultivars and 10 well tested strains to study the symbiotic relationship. The results indicated that effectiveness among the strains and the alfalfa cultivars was great different. Compare with the control uninoculated treatment, inoculating has significantly increased alfalfa dry matter and nodule numbers. And there was great difference among strains for each cultivar. Strains of CCBAUNM006, CCBAU30085, and CCBAU45236 are much better for Zhongmu no. 1, CCBAU30015, CCBAUQH180 and CCBAU45236 for RS line, CCBAU45236, CCBAU30015, CCBAU30085 and CCBAU30015, CCBAU45236, and CCBAU25132 for Vector and WL323 respectively.3. With soil from Wuqiao county Hebei province, Jurong county Jiangsu province, Tongliao inner Mongolian, and Xixian county, Shanxi province, we have done plot experiment for selecting high effictive strains. We selected CCBAUN210, CCBAU30138, and CCBAU96077 as good inoculant for Wuqiao soil and Vector cultivar, CCBAUNMG048-3, CCBAU038-2, CCBAUNM006, CCBAUNMG024-2, CCBAU099-1 for Tongliao, CCBAU048-3,CCBAU048-2 for Loess Plateau, and CCBAU43191, CCBAU3008 for Jiangsu hilly areas.4. Taking Wuqiao county as typical area, we conducted field inoculating experiment with the strains which selected in greenhouse, the result was successful, compare with the control uninoculating treatment, inoculating CCBAUN210, CCBAU30138, and CCBAU96077 increased hay yield 10.2%, 11.9%, and 13.7% respectively., at the same time, the crude protein yield increased 15.63%, 19.63%, and 13.59%. When planted alfalfa with tall fescue, bromegrass and rye grass to establish alfalfa-grass mixture, the results showed that inoculating CCBAU30138 for alfalfa made the yield of total hay was increased 16.3%, 20.5% and 6.8% respectively.5. Applying PCR technique to study the nodule occupy of CCBAU30138 in the field, result indicated that nodule occupy was 47.7% in pure alfalfa and 48.6% in alfalfa-tall fescue mixted. From this experiment, we concluded that CCBAU30138 has higher effectiveness with producing nodules and high competitive capability with the indigenous.6. Combining the knowledge of agronomy, forage, microbiology, and molecule biology , the highly effective symbiotic system between rhizobia and alfalfa was successful.