Study Of Screening High Efficient Rhizobium Of Faba Bean(Vicia Faba L.) In Sichuan & Study On The Decomposing Of Green Manure Of Faba Bean

The tested thirty rhizobia strains were isolated and screened from previous experiment,which matched well with the mainly planted faba bean cultivar Dabaidou in Sichuan,and those strains were isolated from 16 counties in Sichuan.The Stress resistance and Promoting ability of these 30 strains was determined by the conventional method.By low nitrogen double layer pots and low-N nutrition solution culture experiment,high efficient faba bean rhizobia which were best matched of mainly planted faba bean cultivars,Chenghu No.14,Chenghu No.15 and Panzhihua local variety,in Sichuan province were screened from these 30 rhizobia.Multilocus sequence analyses were applied to identify the phylogenetic position of these several strains were screened by matching test.And these several strains were verified through a field experiment,all of treatments were compared with non-inoculation treatments.After that,the highly effective rhizobium bacteria which were initially screened in the field test in the first year were re-screened in the field,all of treatments were compared with non-inoculation treatments.Finally the highly effective rhizobium bacteria suitable for the application in sichuan province were screened.In this study,the decomposition and nutrient release law of faba bean green manure inoculated with or without rhizobium during faba bean cultivation period were preliminarily explored by nylon mesh bag method.The main research results are as follows:(1)The stress resistance test results showed that the salt tolerance of faba bean rhizobia in sichuan was generally poor,only SCAUf148 can tolerate the NaCl concentration of3.5%.86.8% of the strains can grow within the acidity alkalinity scope of pH4-11,these strains with strong acid and alkaline resistant ability.The temperature growth range is narrow of tested strain,the temperature most favorable to growth of 76.7% of the strains is between8~28?.The results of growth-promoting test showed that 96.7% of the strains could secrete IAA,the maximum secretion amount was 21.0 mg/L(SCAUf148).All strains do not produce dissolving circles,but the quantitative determination results of phosphorus solubility in 10 strains which was best matched showed that some strains had organophosphorus solubility,and can dissolve aluminum phosphate,iron phosphate,calcium phosphate.Twopotassium-soluble strains and one iron-secreting strain(SCAUf148)were screened.(2)The matching experiment of 30 strains with the three main cultivars in sichuan.Results,the 10 strains were isolated from different areasand the highly effective rhizobium,The 10 strains were SCAUf8?13?43?48?73?76?110?118?123 and 148.Multilocus sequence analyses identified SCAUf123 as R.fabae,SCAUf48 as R.sophorae,SCAUf8?148?43?13?76?110 as R.anhuiense and SCAUf73?118 were assigned as new potential species of Rhizobium.The 10 strains of highly effective rhizobia screened by the matching test willbe applied in the field experiment.The results showed the yield of 50.0%strains increased significantly by 25.0%~37.7% compared with CK.Among them,SCAUf8 and SCAUf110 had the best effect,whose were re-screened.The grain yield of SCAUf148 was not significantly different from CK,but SCAUf148 was a strain with good stress resistance and promoting abilit.So this strain was re-screened as a backup strain.In order to study the double inoculation effect of two strains with better nitrogen fixing effect,SCAUf8 + 110 double inoculation treatment was also set up in the next year.The second year of field experiment showed that SCAUf110 and SCAUf8+110 could increased significantly by 10.4% ~12.0% compared with CK.In the first year of field experiment,SCAUf43 had the best effect on increasing the yield of green manure than CK,and the accumulation of nitrogen and potassium in green manure treated with SCAUf43 increased significantly by 50.0% and56.9% compared with CK,so the treated samples were collected as decomposition test materials.(3)Using nylon bags method studied the nutrience release tendency of faba bean green manure inoculated with SCAUf43 and without Rhizobium.The results indicated such tendencies,faster decomposition at earlier stage and slower decomposition at later period.The decomposition rate of samples inoculated with SCAUf43 was significantly faster than that of samples not inoculated with Rhizobium in the blooming stage,while the samples in the harvest stage did not show this rule.The decomposition rates of hemicellulose,cellulose and lignin of faba bean green manure also showed a fast-and-slow pattern,and the decomposition rates of hemicellulose and cellulose were faster when inoculated with SCAUf43 than thosewithout inoculated with Rhizobium in the two periods,but whether inoculated with SCAUf43 or not had no significant effect on the decomposition rates of lignin.(4)The nutrient release of faba bean green manure with SCAUf43 and without Rhizobium inoculation was studied.The results showed that the release of N,P and K from faba bean green manure in all treatments was faster in the early stage and slower in the late stage,and the release rate of nutrients was K > N > P.The nitrogen release rate of samples inoculated with SCAUf43 was higher than that of without inoculated with SCAUf43,the difference was significant,but the difference was small.The release rate of potassium was higher in SCAUf43 inoculation than in no inoculation,but there was no significant difference in the release rate of potassium between the two treatments at flowering stage.Phosphorus release rate of inoculated SCAUf43 treatment was lower than that of non-inoculated treatment.