| In order to efficient rhizosphere growth-promoting bacteria with soybean affinity,a total of 36 rhizosphere-promoting bacteria with specific affinity to soybean were screened from soybean rhizosphere by a double screening technique of selective culture medium combined with soybean agglutinin(SBA).Among them,12 strains had the ability to dissolve inorganic phosphorus,9 strains had the ability to degrade organophosphorus,and 15 strains had the ability to dissolve potassium.The results of morphological,physiological and biochemical tests and 16SrRNA gene sequence showed that the 36 strains belonged to Megaterium sp.,Caulobacter sp.,Arthrobacter sp.,Enterobacter sp.,Pseudomonas sp.,Rhizobium sp.and Caulobacter sp.,respectively.The growth-promoting characteristics of 36 strains of soybean-compatible rhizosphere bacteria were tested.It was found that 6 of them had the ability to dissolve tricalcium phosphate more than 100 mg·L-1,4 strains could degrade calcium phytate more than 100 mg·L-1,and 15 strains could hydrolyze potassium more than 10 mg·L-1..All of the 36 strains could produce IAA,13 of which produce IAA with a capacity of more than 10 mg·L-1,17 strains could produce siderphores,and 16 islates displayed three plant growth-promoting traits.Two strains,DN9 and DW12,were selected from 36 strains of growth-promoting bacteria.The luciferase luxAB gene was transferred into the two strains by electrotransformation to generate DW12-L and DN9-L.The colonization dynamics of the labeled strains in soybean rhizosphere were tracked and the effects of the strains on root development and seedling growth of soybean were studied.The results showed that PGPR strain without affinity to SBA could not clonize the soybean rhizosphere,however,the two soybean-compatible strains,DN9-L and DW12-L were able to colonize and reproduce stably in soybean rhizosphere,and significantly promote the growth and root development of soybean.Seven affinity strains with good growth promoting performance were selected for pot experiment.The results showed that DW1,DN9 and DN11 had significant promoting effects on leaf fresh weight,leaf dry weight,effective branch number,single plant bean weight,root fresh weight and root dry weight..Among them,DW1 strain had the best promoting effect on soybean plant growth,and the application of DW1 in soybean yield,root fresh weight,root dry weight,leaf phosphorus content,soil nitrogen content,soil phosphorus content,soil content The amount of potassium increased by 242.35%,3.14%,12.17%,74.58%,2.63%,143.41%,and 4931%,respectively,compared with the control group.The effect of 7 strains of soybean affinity-promoting strain on the growth and yield of soybean was further tested by field test.Further,the field experiment was conducted to test the growth of soybean growth and yield by7 strains of SBA affinity PGPR strains.The experimental results show that DW1,DN9 and DN11 can promote the growth of soybean plants,increase the number of pods per plant,the number of single plants,100-grain weight,3 pods,4 pods,and increase soybean yield.Compared with the uninoculated control,DN9 showed the best growth effects on The 100-grain weight,number of grains per plant,and number of pods in soybean inoculated with DN9 were increased by(respectively 37.9%,70.9%,and 65.9%than those in uninoculated control. |
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