Application Research Of Microbial Seedling Substrate And HG15-7 Agent

Paenibacillus polymyxa HG15-7 is a PGPR strain with rhizosphere colonization ability,plant growth promotion and disease control.MSS-PGB is a microbial seedling substrate for vegetable formulated with HG15-7.In this study,under the greenhouse cultivation conditions,verifying the application effect of MSS-PGB and HG15-7 bacteria on pepper;and further optimize the formulation of MSS-PGB to prepare a microbial seedling substrate MSS-PGS with stable effect and good storage performance;At the same time,the conditions for sporulation of HG15-7 strain were optimized to ensure the configuration of MSS-PGS.The results are as follows:Under greenhouse cultivation conditions,the combined application of MSS-PGB and HG15-7 can promote the growth of pepper,increase the chlorophyll content,the root activity,the yield and fruit quality,Chlorophyll content increased by 12.37%?30.84%,root activity increased by 5.97%?43.46%and yield increased by 20.23%,respectively.The contents of protein,vitamin C and soluble sugar in pepper fruits increased by 20.82%?44.46%,18.40%?29.49%and 12.15%-47.90%,respectively.In addition,the combined application of MSS-PGB and HG15-7 bacteria increased the enzyme activity in the rhizosphere soil of pepper,increased the content of available nitrogen and phosphorus,increased the number of rhizosphere bacteria and actinomycetes,reduced the number of fungi.The activities of phosphatase,urease,catalase and sucrase in rhizosphere soil increased by 4.01%?29.26%,8.39%?26.72%,4.98%?13.67%and 17.38%?44.69%,respectively.The available nitrogen and phosphorus contents in rhizosphere soil increased by 5.36%?25.02%and 5.84%-19.16%.The number of culturable bacteria and actinomycetes in rhizosphere soil increased by 41.4%?81.%and 14.54%?67.06%,respectively,and the number of cultured fungi decreased by 32.73%?71.47%.The MSS-PGB was further optimized to prepare a microbial seedling MSS-PGS with stable storage performance.The pH,EC value,bulk density,total porosity,venting porosity and water holding porosity of MSS-PGS are in line with general vegetable seedling substrate standards.During the storage of MSS-PGS,the survival of HG15-7 in the matrix was stable.When stored for 180 days,the survival of HG15-7 in MSS-PGS could still reach 6.03×107 cfu·g-1;Breeding peppers and cucumbers with MSS-PGS after 180 days of storage,the promoting effect on pepper and cucumber seedlings,the rhizosphere colonization ability of HG15-7 and the control effect on the disease were relatively stable.The colonization density of HG15-7 in the rhizosphere matrix of cucumber reached 107 cfu·g-1and the colonization density of HG15-7 in pepper and cucumber roots reached above 105 cfu·g-1.respectively.The control effect on pepper blight still reaches 64.45%.To ensure adequate spore suspension for the preparation of microbial seedling substrate MSS-PGS,the single factor test and orthogonal test were used to optimize the spore condition of HG15-7.Results,drying 60 mesh sieve dried bean dregs 25 g·L-1,NaCl 0.5 g·L-1,KCl(0.25 mol·L-1)10 ml·L-1MgCl2(2 mol·L-1)and glucose(1 mol·L-1)20 ml·L-1,initial pH 6.5,40%liquid loading,200 r·min-1,at 30? the spore formation rate reached 100%at 78 h.