Study On Screening Of Biocontrol Strains Of Bacillus Spp. Isolated From Qinghai-Tibet And Its Practical Application Effect

Bacillus is a type of plant rhizosphere-promoting bacteria that produces plant-derived metabolites after colonization of the roots.Some of these substances act as inducing factors and induce plant tolerance.In addition,Bacillus can improve the micro-ecology of plant root soils,and can convert nutrients that are not directly absorbed by plants in the soil into an absorbable state and promote plant growth.In this paper,Bacillus strains resistant to disease,growth,low temperature and salt tolerance were selected,and strains with good comprehensive performance were selected and applied to the control of field diseases and the preparation of antifreeze microbial fertilizers.The actual promotion and application provide a theoretical basis.1.Screening of Bacillus spp.strains isolated from Qinghai-TibetIn this experiment,46 strains of Bacillus licheniformis isolated from different habitats in Qinghai were selected to explore their growth and stress resistance characteristics.By detecting the growth-promoting properties of the strain,the strains Bacillus sp.GBSW19,Bacillus sp.LLTC93,Bacillus atrophaeus CKL1,Bacillus sp.LNXM10,Bacillus velezensis GBSW11 and Bacillus atrophaeus TS1 were screened to promote the seed germination and seedling growth of rice.Significant growth promotion.By screening the antagonistic activity of the strain,the strains Bacillus atrophaeus TS1,Bacillus sp.NMCC46,Bacillus atrophaeus NMTD54,Bacillus toyonensis NMTD92,Bacillus halotolerans DGL6,Bacillus atrophaeus CKL1,Bacillus velezensis GBSW11 were screened to inhibit fungi and bacteria.By testing the low temperature resistance of the strain,17 strains which can grow normally under the low temperature condition of 4℃were screened,among which the strains Bacillus sp.LNXM10,Bacillus sp.RJGP41 and Bacillus sp.GBSW19 were the most prominent under low temperature conditions.Compared with other strains,obvious colonies were observed at 3℃ at 4℃.By detecting the salt tolerance of the strain,the strains Bacillus sp.NMCN1,Bacillus sp.GBSW19,Bacillus sp.NMTD17,Bacillus safensis GBSW22 and Bacillus subtilis SYST2 were screened and grown normally on a plate containing 15%NaCl,stronger than the salt tolerance of other strains.2.Effect of Bacillus licheniformis preparations on rice growth in Qinghai-Tabit areaIn order to explore the effects of strain preparations on rice growth in Qinghai-Tibet region,we selected Bacillus sp.TS1 and Bacillus velezensis GBSW11,which have a promoting effect on rice and have inhibitory effects on fungi and bacterial pathogens,and increased against Fusarium graminearum and Verticillium dahliae.Add the strain Bacillus polymyxin E681 with strong inhibition effect,using Bacillus sp.FZB42 as indicator strain,was made into fermentation broth,soaked in rice seed stage,and sprayed on rice seedling stage and mature stage.The results showed that the incidence of rice sheath blight in rice fields without pesticide treatment was 65.50%,and the disease index was 51.46%.The incidence of rice sheath blight was 35.41%and the disease index was 21.17%.The disease prevention effect was 58.86%.The incidence of rice field disease treated with Bacillus fermentation broth was 46.82%,and the disease prevention effect was 58.08%.At the same time,we tested the yield of rice.The results showed that in the rice field without chemical treatment,the yield per stalk of rice was 223.75g,and the weight per thousand was 20.71 g.The weight of the rice field sample controlled by conventional chemicals was 254.08g,the weight of 1000-grain was 22.72g,and it was fermented with Bacillus.The maximum yield of the panicle weight of the liquid-treated rice field was 280.73 g,and the highest yield of the thousand-grain weight was 23.25 g.Bacillus is non-toxic and non-polluting,and has a larger promotion and application prospect than pesticides.This study provides some data support for the application and research and development of biopesticide.3.Low temperature tolerance and application of Bacillus salt-tolerant to fertilizerUsing nitro-compound as a fertilizer variety,we explored the effect of low-temperature and salt-tolerant bacillus strains combined with fertilizer on the growth of cucumber under low temperature conditions.This study selected to promote the growth of plants and enhance the cold resistance of plants bacillus sp.GBSW19 with salt-tolerant properties was developed as a fertilizer coating agent,wrapped on the surface of the fertilizer,and the prepared fertilizer was applied to cucumber to see the antifreeze effect of cucumber at low temperature.On the one hand,this study simplifies the fertilizer coating process,improves the state of the fertilizer coating agent,and on the other hand,innovatively adds natural plant source hormones,screens out the best hormone ratio,enhances the antifreeze effect of the fertilizer,and compensates for the natural nature of the bacillus.The effect of attenuation is reduced.The prepared fertilizer was applied to the two-leaf stage seedlings of cucumber.The results showed that the leaves of cucumber two-leaf stage seedlings began to wilting at 10℃ after 72h,and the leaves of the treatment group were intact,and the antifreeze rate was as high as 95%.This study provides theoretical and data support for the application of bacillus in the chemical industry.