Primary Study Of The Control Mechanism Of 2-allyl Phenol And 4-butanoyl Phenol On Wheat Rhizoctonia Root Rot

With the means of microscopy, High performance liquid chromatography (HPLC), and biochemical techniques, this study evaluated the ftmgicidal activities of 2-allyl phenol (LvDi) and 4-butanoyI phenol (YinTai). Also investigated were pharmacology of the two fungicides in wheat and their mechanisms inhibiting Rhizoctonia cerealis in vitro.Studies on growth rate, spore-bourgeoing rate and turbidity disclosed that LvDi and YinTai inhibited the growth of Rhizoctonia cerealis, Botrytis cinerea, Fulviafulva, Sporisoriian reiliana, Physalospora piricola, Valsa mali, Piricularia oryzae, and Pythium aphanidermatum. The In vitro median effective concentrations (EC50) ranged from 1.0/ml to 60.0g/ml. The results suggested that the two fungicides had broad fungicidal spectrum.HPLC was applied to investigate the intake and distributional mechanism of LvDi and YinTai in wheat seedling. With a treatment level of LvDi at 500 ug/ml, the intake reached 389.67g per gram of plant tissue in 72 h (standard deviation (SD=9.5). YinTai was not detected in the seedling treated with different levels of the fungicide. In comparison with carbofuran (a typical intake reagent) as well as thiram (a typical non-intake reagent), this was the first time that revealed LvDi could be intaken into wheat seedling. It was transported in a high speed from the root to the top of the seedling. The accumulation levels of LvDi in stem (Y1) and leaves (Y2) were positively correlated with treatment time (X) in linear relationships of Y1=2.9586X+44.217 and Y2=1.6281X-4.4412, respectively. The corresponding coefficients of determination were 0.8486 and 0.8591, respectively. LvDi was distributed in whole seedling at 72 h after the treatment. The accumulation levels at root, stem, and leaves were 99.70 (SD=10.58), 243.86 (SD=19.87), and 137.37 (SD=2.44) ug per gram of plant tissue, respectively. CCCP, temperature, and the properties of amino acid and sucrose significantly affected the intake of LvDi by wheat seedling. This indicated that wheat tend to intake and transport it actively.The inhibition mechanisms of LvDi and YinTai on the growth of Rhizoctonia cerealis were studied by means of microscopy, membrane permeability, HPLC, cell wall degradingenzyme, and respiration assays. There is no evident difference in the fungal toxicity of the two chemicals on the growth of the pathogen on PDA media of different pH. The space between hyphal branches of Rhizoctonia cerealis was significantly reduced when it was incubated and grown on the PDA media containing LvDi and YinTai. The two fungicides did not affect membrane permeability and the content of ergosterol in Rhizoctonia cerealis. They inhibited the activities of three pectinases (PQ PMG, PMTE) of Rhizoctonia cerealis. The inhibition of respiration increased with the concentration of the fungicides, but did not change notably with time in the treatment levels ranging from 10g/ml to 100g/ml. At 1g/ml, the two fungicides had no effect on respiration.