Study On Control Of Tobacco Black Shank Disease With Biochar-based Fertilizer Of Prickly Ash Seed

Tobacco black shank disease is one of the major destructive diseases of tobacco,caused by Phytophthora parasitica var.nicotianae.Currently,amide pesticides such as metalaxyl and enylmorpholine were mainly used on black shank control,which resulted in series of problems including pesticide residues,environmental pollution and pathogen fungicide-resistance.Therefore,it is of great significance to develop efficient,safe and eco-friendly biocontrol measures,because long-term application of chemical fertilizer lead to the decline in tobacco quality,soil hardening,organic matter reduction and imbalance of rhizosphere microorganisms as well as increasing of soil borne diseases.In this study,developed a new type of organic fertilizer called biochar-based biocontrol bacterial fertilizer of prickly ash seed,which were integrated of plant-based antimicrobial materials?Chinese prickly ash seed,PAS??Zanthoxylum bungeanum?,soil improvement materials?biochar?and antagonistic microbial materials?Bacillus subtilis Tpb55?.The results were as follows:?1?The chemical components of PAS were identified,and its disease control potential was evaluated.GC-MS revealed that the main components of PAS extract were cis-Vaccenic acid?40.81%?,n-Hexadecanoic acid?15.67%?,9,12-Octadecadienoic acid?Z,Z?-?15.25%?,Ethanone-1-?2-hydroxy-4,6-dimethoxyphenyl?-?10.32%?,cis-9-Hexadecenoic acid?6.21%?and Psilocin?11.75%?.A total of 28 volatiles were identified by HS-SPME-GC-MS with dominant compounds of Sabinene?13.45%?,?-Myrcene?7.72%?,Linalool?6.22%?,Piperitone?8.36%?,D-Limonene and?-Phellandrene?16.93%?.Among them,Linalool and Piperone showed stronger inhibitory activity against P.nicotianae with IC₅₀ of 18.03?L/L and 51.99?L/L.PAS showed potential to be used as a fumigant on tobacco black shank disease control,which can lessen the disease severity,promote plant growth,improve the capacity of soil microorganisms on carbon sources utilization,and increase soil physichemical properties.?2?Under scanning electron microscope,the Tamarix?Tamarix chinensis Lour.?biochar prepared at three temperatures had obvious pore structure.The pH,conductivity and ash content of the biochar were positively correlated with the temperature in a certain range,but the C/N ratio and water retention rate decreased first and then increased with the increase of temperatur.Tamarix biochar at high temperatureharbered higher content of K,Ca,Na and Mg.The microbial loading capacity of Tamarix biochar prepared at 300°C was significantly higher than that of other treatments.B.subtilis Tpb55 was well loaded on Tamarix biochar.The pot experiment showed that the application of biochar and Bacillus subtilis Tpb55 had a synergistic effect on the control of tobacco black shank,and could significantly suppress the root colonization of P.nicotianae?RT-qPCR?.Moreover,the soil pH,conductivity,carbon nitrogen ratio,available phosphorus,available potassium and alkali hydrolyzed nitrogen content were also significantly improved.?3?The organic fertilizer prepared by prickly ash seed,rice husk biochar and Bacillus subtilis Tpb55?PBB?was investigated.Rice husk biochar has the potential to be used as a soil amendment and organic fertilizer with high ratio of C/N?215.75?.The results of fermentation experiment showed that the rice husk biochar could promote the growth of Tpb55 strain,and served as the most significant factor affecting the fermentation.Germination and maturity experiments indicated that the fertilizer obteined exhibited neutral pH,high available potassium?7573.90mg/kg?and ammonium nitrogen?131.47 mg/kg?,which was in line with the national standard of compost production.The application of PBB can reduce the disease index of black shank disease as well as the population of P.nicotianae,and increase the soil pH,available potassium,alkali hydrolyzed nitrogen and organic matter.The?-diversity of soil fungi and bacteria was significantly increased with PBB application.PCoA analysis suggested that the structure of soil microbial community was shifted.PBB also increased the abundance of Bacillus,Pseudomonas,Thermomonas and Dyella while Fusarium was significantly suppressed compared to that of the control.