Effects Of Microbial Fertilizer And Biochar Applications On The Yield And Quality Of Pinellia Ternata And Soil Microecology

The dried tuber of Pinellia ternate,a species of Araceae family,is one of the most widely used Chinese traditional herbs.With the pharmaceutical development and the exhaust of wild P.ternate resources,the artificial cultivation become the most important source of the herb.However,the continuous cropping obstacles and the soil borne diseases make serious restrictions to the artificial cultivation of P.ternate.Beneficial microbial agents can regulate plant metabolism,enhance root activity to take up nutrients from soil and improve the fertilizer utilization of crops.Moreover,they can secrete pathogen inhibitors,inhibit the propagation of soil pathogens and reduce the incidence of crop diseases.Biochar can improve soil nutrient structure and adjust soil microbial structure.Nevertheless,the applications of biochar and/or microbial agents to alleviate the continuous cropping obstacles of P.ternate have not been reported.In this study,two potting experiments and a field experiment were conducted to test the effects of different doses of three kinds of bacterial agents,i.e.,Bacillus licheniformis F1,Bacillus amyloliquefaciens PC06 and Streptomyces sp.5406,and biochar(600°C charred rice husk biochar)on the growth,disease incidences,tuber yield and quality of P.ternate.Meanwhile,the effect of the bacterial agents and biochar on the rhizosphere microbial community of P.ternata was analyzed using high-throughput sequencing.The purpose of this study is expected to provide experimental basis for applying microbial and biochar fertilizers to reduce the soil borne diseases and alleviate continuous cropping obstacles in P.ternata production.The main results are as follows:1.The pot experiment showed that,the applications of bacterial agents significantly improved the plant growth and development,reduced the disease incidence and enhanced the tuber yield and quality of P.ternata.Among the treatments,the B.licheniformis showed the best effects.The disease incidence was lowest in the applications of medium and high doses of B.licheniformis,and the incidence rate was close to zero.The highest tuber yield was found in the application of high dose B.licheniformis,in which the fresh tuber yield was 85.91% higher and the dry tuber yield 68.34% higher than the control.The total alkaloid content in the dry tuber of the dose B.licheniformis treatment was 0.288‰,which was significantly higher than that of other treatments.2.The applications of bacterial agents significantly affected the microbial community structure in soils,reduced the diversity and abundance of the fungal community but increased the diversity and abundance of the bacterial community,resulted in the reduced the fungal/bacteria ratio and the evolvement of soil to bacterial and fallow types.The application of B.licheniformis significantly reduced the relative abundances of the pathogenic fungi Fusarium and Acremoniumzonatum of P.ternata in the soil,increased the bacterial abundances of Lysobacterium and Pseudobacteria enhance the biocontrol abilities and Bacillus with the ability to release phosphorus and potassium from soil.The activities of urease,phosphatase,catalase and peroxidase in soil were enhanced in the application of B.licheniformis,which may be helpful for the disease resistance of P.ternata and the activation of poorly soluble nutrients in soil.3.The applications of biochar significantly improved the plant growth and tuber yield of P.ternata,with the high dose of 6% being the best.The plant height,leaf length and leaf width and the SPAD reading of leaves increased by 86.32%,55.70%,106.85%,and 40.18%,respectively,in the high-dose treatment compared to the control at growth stage.The fresh tuber yield of low(2%),medium(4%)and high dose(6%)treatments was 64.01%,92.53%,and 102.17%,respectively,higher than that of the control.The dry tuber yield showed a similar trend to the fresh yield.The applications of biochar significantly reduced the disease incidence of P.ternata seedlings in the growing season.The incidence of medium-dose treatment was the lowest at the spathe stage,which was 53.21% lower than that of the control.The application of biochar significantly increased the water-soluble extract,organic acid and total alkaloid content in dried tuber of P.ternata.The water-soluble extract of medium-dose treatment was 2.48% and organic acid content 31.29% higher than that of the control,all the differences were statistically significant.4.The applications of biochar significantly increases the available nutrient contents in the soil,and the available nutrient content showed an increasing trend with the increase doses of biochar application.Biochar treatment reduced the relative abundance of Ascomycota but increased the relative abundance of Zygomycota and Acremoniumzonatum in the fungal community.The relative abundances of Acidobacteria and Chioroflexi were also reduced,but the Proteobacteria,the Pseudarthrobacter and Flavobacteria with biocontrol functions and the Bacillus with the functions of releasing phosphorus and potassium from soil were increased in the bacterial community in the treatments of biochar applications.5.The field experiment showed that,applications of B.licheniformis,B.amyloliquefaciens and Streptomyces significantly improved the growth potential of P.ternata and increased the tuber yield and quality of P.ternata.Observations at growth stage stage indicated that,the plant height,leaflet length,leaflet width and SPAD reading were increased by 12.75%,12.52%,12.76% and 17.03%,respectively,in the application of B.licheniformis than in the control treatment.The fresh tuber yield in the treatments of Streptomyces and B.licheniformis applications increased by 60.10% and 48.03%,respectively,than in the control treatment.The water-soluble extract in dried tuber increased by 1.20% and the organic acid content by 9.83% in both treatments and the total alkaloid content by 3.70% and 3.29%,respectively,in the treatments of Streptomyces and B.licheniformis applications,compared with in the control group.All the differences from the control were significant.However,there was no significant difference in the contents of the water-soluble extract,organic acid and the total alkaloids in dried tubers between the treatment of B.amyloliquefaciens and the control,although those of the former were slightly higher than those of the later.Our results laid a solid foundation for the popularization and utilization of these bacterial fertilizers and biochar in the plantation of P.ternata.