Efficacy Of Paenibacillus Polymyxa G15-7 In Growth Promotion&Disease Control Of Pepper And Its Application

Paenibacillus polymyxa G15-7 is a rhizosphere bacterium isolated from wheat rhizosphere.The antifungal effect of G15-7 against Phytophthora capsici was analyzed both in plate and pot assays and by filed experiment,the growth promoting effects of G15-7 on pepper was confirmed and the effects on pepper rhizosphere micro ecology was analyzed to understand its growth promoting effects.Meanwhile,the fermentation conditions were optimized and agricultural waste was used as accessories to develop functional microbial matrix,providing the theoretical basis for the further application.1.Identification of Paenibacillus polymyxa and its characteristicsAccording to the morphological characteristics,physiological and biochemical characteristics and sequence analysis of 16S rDNA,G15-7 was identified as Paenibacillus polymyxa;G15-7 soil had strong colonization abilities in pepper root and its rhizosphere soil,maintaining certain colonization densities in a long time,the colonization densities reached above 104cfu·g-1 both in pepper root and its rhizosphere soil at late fruiting stage;at the same time,G15-7 has a broad antibacterial spectrum,with antibacterial activities on 9 kinds of plant pathogens.2.Control effect of G15-7 on Phytophthora capsiciG15-7 significantly inhibited the mycelia growth,zoosporangium formation,zoospore release and germination of resting spore of Phytophthora capsici,and in pot experiment,G15-7 had a significant control effect on Pepper Blight,with the control effect of 93.30%.3.Growth promoting effects of G15-7 on pepperG15-7 significantly promoted the growth of seedling and field pepper;G15-7 significantly increased the chlorophyll content and root activity,compared to CK,chlorophyll content increased by 29.13%～62.05%,root activity increased by 27.07%～317.81%;G15-7 significantly improved the fruit quality indexes and yields of pepper,compared to CK,protein content,soluble sugar and vitamin C content increased by 73.81%.58.18%and 102.80%respectively,and the yield increased by 29.73%.4.Regulation of G15-7 on rhizosphere soil microecology of pepperG15-7 significantly increased soil enzyme activities in the rhizosphere of pepper,compared to CK,urease activity increased by 7.69%～31.43%,phosphatase activity increased by 1.22%～222.64%,invertase activity increased by 16.49%～118.75%,and catalase activity increased by 6.02%～61.38%;G15-7 significantly increased the amounts of bacteria and actinomycetes in rhizosphere soil of pepper,but reduced the amount of fungi,the number of bacteria increased by 35.44%～207.20%,and the number of actinomyces increased by 16.98%～73.68%,but the number of fungi reduced by 14.29%～74.03%;G15-7 significantly increased the contents of available nitrogen and available phosphorus in pepper rhizosphere soil,compared to CK,the contents of available nitrogen and available phosphorus increased by 7.69%～160.00%and 19.46%～107.60%respectively.5.Optimization of fermentation conditions of G15-7By single factor test and orthogonal test,the fermentation conditions of G15-7 were optimized,and the optimal medium was 1%Glycerol,0.1%KNO3,0.7%K2HPO4,0.2%KH2PO4,0.01%MgSO4·7H2O,the optimum culture condition was 30℃,50%volume of 250 mL,3%inoculum size,pH 6.0,160 r·min-16.Effect of functional microorganism substrateFunctional microbial substrates of T1 and T2 were made with G15-7,and its effectiveness was verified,functional microbial substrates T1 and T2 had no significant effects on pepper germination,but significantly promoted pepper growth,cultivating sound seedling,with the sound seedling indexes increasing by 23.53%and 11.76%respectively,meanwhile,G15-7 had significant control effect on Pepper Blight under artificial inoculation,the control effect of functional microbial substrates T1 and T2 against Pepper Blight were respectively 80.77%and 76.92%.