Synergistic Actions And Mechanisms Of Tea Saponion To Fungicides

Inhibition on six kinds of plant pathogens and synergistic action to three kinds of fungicides of tea saponion were tested in the laboratory. Bioassay results showed that tea saponion had apparent inhibition to mycelial growth and spore germination of Pyricularia grisea(PG). Tea saponion (TC) has weak inhibition against mycelial growth and spore germination of Botrytis cinerea (BC), TS had synergistic actions to Tricyclazole (Tr), The mixture (Tr.TS=l:3) had obvious synergistic action against PG, in vitro condition with CTC value!58.05 for mycelial growth inhibition and 142.04 for spore germination inhibition. In vivo test in glass house showed that the mixture (Tr: TS=1:3) had synergistic action against rice blast, synergistic coefficient is 1.35. TS had synergistic action, with a CTC value 163.84 of mycelial growth inhibition, when mixed with Benalaxyl (Be) in a ratio of 4:1 against BC. In vivo test also showed that this mixture had synergistic action against gray mould of cucumber, with a synergistic coefficient of 1.88, but this mixture had no synergistic action against spore germination of BC.The mechanism of TS's synergistic action to several fungicides was primarily studied. The results showed that Tr, TS and their mixture (1:3) had weak effect on the penetration of PG, but apparent inhibition to the synthesis of PG protein. Inhibition of TS is stronger than that of Tr. In the meanwhile, TS and its mixture with Tr apparently enhanced the SOD activity of PG and inhibit POD activity. A poisonous substance-H2O2 in the cell of PG was over accumulated, the cell's normal metabolism was disturbed severely, the cell itself was hurt eventually because the two enzymes were affected. Both TS and TS/Be mixture caused easy penetration of membrane, with a concentration dependent curve. Be itself has little effect to the penetration of membrane. The mixture (1:4) damaged the cell membrane more severely than single, resulting in the cell content over-leakage. The over-leakage may be one of the reasons of synergistic action. At the same time, both TS and TS/Be mixture had evident inhibition to protein synthesis of BC, and enhanced SOD activity of BC. Be itself has little effect in the two aspects.Based on experimental result and considered comprehensively the physical and chemical characteristics, source, processing of TS, this paper put forward that exploiting TS and applying it into pesticide field as a synergist of fungicides haveextensive use.