The Inhibition Effect Of Nano-silver On Plant Pathogenic Fungi

In this dissertation,the antifungal activities of nano-silver to phytopathogen were studied.Protective effect on rice blast of nano-silver were mainly detected by in vitro inoculation.Results were as followed:The toxicity of nano-silver to 15 plant pathogenic fungi,Colletotrichum musae,C. capsici,Fusarium oxysporum f.sp.vasinfectum,F.oxysporum f.sp.Cucumerinum, Pyricularia grisea,Alternaria brassicae,C.higginsianum Sacc,Rhizoctonia solani, Peronophythora litchii,P.capsisi,F.oxysporum f.sp.cubense,Sclerotinia sclerotiorum, Penicillium digitatum,Botrytis cinerea and Sclerotium rolfsii were determined by using bioassay.The results showed that the nano-silver had substantial inhibitory activity against mycelium growth of 15 tested fungi with EC₅₀from 2.7267μg·mL^-1to 36.2465μg·mL^-1,of which the inhibited effects on R.solani(EC₅₀=2.7267μg·mL^-1)and C.musae(EC₅₀= 3.8871μg·mL^-1)were the best.The toxicity of nano-silver on spore germination of 9 tested fungi were stranger than on mycelium growth of the fungi.The EC₅₀were from 0.0275μg·mL^-1to 1.0927μg·mL^-1,of which the inhibited effects on M.grisea (EC₅₀=0.0275μg·mL^-1)was the best.However,there were little inhibitory activity on B. cinerea,S.rolfsii and P.digitatum.The study on toxicology of nano-silver to phytopathogen showed that the nano-silver could induce the cells of hyphae distorted,expanded,breakdown and wilted.It could also reduce the respiration of mycelia.The inhibition rate of the respiration was 63.05%to A. brassicae,and 57.71%to M.grisea after inoculated in the nano-silver for 2 hours (concentration:9μg·mL^-1.Nano-silver could damage cell membrane and increase cell permeability.After inoculated in the 9μg·mL^-1nano-silver for 2 hours,the permeability of the hyphal cell membrane was about one time higher than control check.It was possible that the distortion of hyphae' cells was due to the increase of membrane's permeability.The result of in vitro inoculation technique showed that protective efficacy of nano-silver was 72.23%to the rice blast under the concentration of 60μg·mL^-1.The protective efficacy were 20.14%and 47.91%under the concentration of 20μg·mL^-1and 40μg·mL^-1 respectively.It was suggested that nano-silver could be developed into the fungicide.