A Study On Solid Granule Of Bioherbicide Sclerotium Rolfsii Strain SC64

The bioherbicide made from Sclerotium rolfsii strain SC64,which was firstly isolated from an invasive alien weed Solidago canadensis,can be used to control broadleaf weeds in cropping wheat(rape)-rice fields,cropping wheat-corn and gramineous lawn.In previous studies,we have developed a technology for mas-production of solid granules containing mycelium by solid fermentation of crop straw and waste.However,solid fermentation cycle takes 7-10 days or even longer,rough granules are not uniform,and shelf life of the granules is shorten due to the loose growth of mycelia.These negatively impact commercialization potential and the value of practical application.Hence,in the present study,submerged fermentation replacing solid fermentation shortened the time-consuming of mass-production procedure and improved shelf life and increased herbicidal efficacy.An improved mass-production technique of S.strain bioherbicide would be established to provide theoretical basis with this product commercilization.Two production process procedures of solid granule were established as the following:Firstly,submerged fermentation-centrifugated mycelia-straw powder made through grinding and sieving-pelletized(The weight ratio of power,mycelia of Sclerotium rolfsii,carbon-white and water=30:35～55:1:12～16)o—air-dried to 10%water content--stored.Secondly,submerged fermentation—centrifugated mycelia--straw powder made through grinding and sieving-pelletized straw powder granule(powder,carbon-white and water=30:1:75～100)—re-pelletized through mixed straw powder granule and mycelia(the weight ratio of straw powder granule and mycelia=1:1.17～1.83)—air-dried to 10%water content-stored.The storage is an important factor to affect the pentential of commercialization of bioherbicide products.Hence,the shelf life of solid granules of Sclerotium rolfsii was studied under different conditions.The solid granules were stored under four conditions of room temperature-vacuum,room temperature-normal pressure,4℃-vacuum and 4℃-normal pressure.Mycelium germination and pathogenicity of the granules were regularly tested to determine the optimal storage conditions.After four months’ storage the results show that under room temperature or 4℃ at normal pressure,mycelium germination of solid granules were still as high as 60%～70%.In particular,under room temperature-normal pressure,mycelium germination and pathogenicity of solid granules kept at 68.1%and 65.7%respectively.After 9 months,the parameters still were around 49%and 45%respectively.However,under 4℃ temperature-normal pressure,they only were at around 23%and 20%.Moreover,in whatever room temperature and 4℃ under the vacuum conditions,mycelium germination rate and pathogenicity of solid granules were reduced to 5～0%and 10-0%respectively after storage four months.In addition,the storage of room temperature and normal pressure is easy and lowest-cost.The room temperature-normal pressure storage may be the suitable commercializing storage method for solid granule bioherbicide of S.rolfsii SC64.The great potential regrowth of Solidago canadensis L.is the key factor to influence its control effect despite input of a large amount of manpower and material resources.Based on the previous study,field trial on a control of S.canadensis was conducted under the populus tree in the Lishui of Nanjing city on August 21,2014.Three treatmens were designed as the plowing plus application of bioherbicide Junkekuo with S.rolfsii SC64(solid fermentation substrate of sclerotium rolfsii strain SC64)at 120g/m2,chemical herbicide glyphosate and blank control.Results showed that the plant mortality of both bioherbicide and chemical herbicide treatment reached above 87%at 15d,and the former even closed to 100%control efficiency while glyphosate got 93.42%control effect at 30d.Therefore,those two kinds of treatments could control S.canadensis effectively at the early stage.However at 90 and 180 DAI,when the regenerations of underground rhisome were investigated,the average number of regeneration of S.canadensis only were 5.17/m2 and 9.25/m2 in plowed-bioherbicide plots,while in glyphosate treatment plot they were 27.20/m2 and 46.24/m2.This indicates that plowed-treated with S.rolfsii SC64 not only controlled sexual reproduction of S.canadensis,but also completely eliminated its underground rhisomes.Glyphosate only effectively reduces the regeneration ability of the underground part.Therefore,the combination of plows and application of the bioherbicide may be one of greatly potential control strategies for S.canadensi.In order to detect weed control effect of solid granules of bioherbicide Sclerotium rolfsii SC64,pot and field trials were conducted in the greenhouse at Pailou experimental base of Nanjing Agricultural University and wet direct seeded rice field at Jinagpu Farm.The doses of SC64 solide granule were designed for pot-experiment as 30kg/ha,60kg/ha,90kg/ha,120kg/ha,240kg/ha and 480kg/ha.The plant mortality was mainly measuered at 14DAI.The field experiment trials were designed 9 different treatments:chemical weeding,manual weeding,Junkekuo 600kg/ha,Junkekuo 100kg,solid granules 120kg/ha,180kg/ha,240kg/ha,360kg/ha and blank control.We test and evaluat plant mortality(%)at 14DAI and 28DAI and fresh weight reduction(%)at 28DAI respectively.The results show that with the dosage increase,weed control efficiency of solid granules increased apparently.In greenhouse experiment,when concentration of SC64 solide granule were 240kg/ha and480kg/ha,the plant mortality reached 70%and 100%accordingly.In the field trial,the plant mortality(%)at 14DAI could reach 60.9～69.1%,the fresh weight control(%)at 28DAI is 46.2%-75.5%.The plant mortality and fresh weight control were 56～82.8%and 56.8～83%respectively.Based on these above studies,solid granules may be great potential bioherbicide to control broadleaf weeds effectively.In conclusion,new solid granule of bioherbicide Sclerotium rolfsii SC64 can extend the storage period,and maintain high activity of the mycelia,consequently reduce the actual application dosage of unit area.This technique for mass-production of the solid granule has a high potential value of commercialization.