Effects of Root Exudation from Carya cathayensis on the Growth and Phosphorus Activation Ability of Phosphorus-Mobilization Bacteria
[Objective]Studying the impact of root exudation of Carya cathayensis(REC)on the growth and phosphorus(P)activation ability of exogenous phosphorus solubilizing bacteria in C.cathayensis is beneficial for further understanding the interaction between microorganisms and plants,and provides effective ways and scientific basis for alleviating P limitation in C.cathayensis forests.[Method]The liquid shake flask and soil culture experiments were conducted to study the effects of REC on the growth,reproduction,and P mobilization of two strains(Lysobacter enzymogenes CQ18 and Paenibacillus polymyxa QP22)that can mineralize organic P components.[Result]The results showed that application of REC had no significant effect on the growth of strain CQ18 in liquid culture,but promoted the reproduction of strain QP22.After inoculation in the liquid culture medium with lecithin as the sole P source,the acid,neutral,and alkaline phosphatase activities significantly enhanced;the soluble P concentration showed a trend of increase followed by a decrease and was significantly higher than that of the uninoculated treatment.Among the treatments inoculated with strain CQ18,the average soluble P concentration of the treatment at low level of REC was the highest(41.93 mg·L-1),while the treatment without REC was the lowest(37.01 mg·L-1)Among the treatments inoculated with strain QP22,the average soluble P concentration of the treatment in middle level of REC was the highest(30.14 mg·L-1),and the high concentration REC treatment was the lowest(18.09 mg·L-1).The number of strains,soil available P content and acid phosphatase activity in the inoculated soil showed a trend of increase followed by a decrease,while were all higher than those in the non-inoculated soil.At harvest,the number of tested strains in soils and soil acid phosphatase activity of treatments containing REC were higher than those in the treatment without REC,but there was no significant difference in soil avaliable P content between them.[Conclusion]Phosphatases could be of utmost importance in the mineralization of the organic P by strains of CQ18 and QP22,and REC could promote,their growth and P mobilization.Therefore,strains of CQ18 and QP22 are potential to be used as biofertilizer in Carya cathayensis forests.
root exudation of Carya cathayensisphosphorus-mobilizing microbeavailable phosphorusphosphatase
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