The Growth-promoting Effect By White-rot Fungi And Its Degradation To Chlorothalonil And Metalaxyl

Chlorothalonil is a tetrachlorinated benzonitrile fungicide widely applied in rice, wheat,beans, vegetables and fruit trees. Metalaxyl is an important acylanilide fungicide typicallyused to protect crops against diseases caused by oomycetous fungi such as downy mildew,late blight and millet downy mildew. These two fungicides are heavily used because of theirhigh efficiency, but its high residual also caused serious pollution to environment. White-rotfungi are known as capable to degrade a wide spectrum of pollutants. However, oomycetousfungicides degradation by white-rot fungi is seldom investigated. In order to verify thedegradation ability of white-rot fungi to Chlorothalonil and Metalaxyl, the investigations werecarried out in this study. Phlebia sp. Y3667and Cerrena unicolor Y4941were screenedfrom70strains of white-rot fungi and used to degrade Metalaxyl and Chlorothalonil,respectively. This study aimed at the development and application of white-rot fungi asmicrobial soil conditioner and plant growth-promoting rhizofungi (PGPB) provide theoreticalbasis and superiority strains. The influence of the two strains to the growth of crop seedling isalso conducted. The results show as follow:(1)70strains of white-rot fungi have the capabilities to degrade four fungicides indifferent levels. The most effective strains are as follows (degradation rate>80%): Cerrenaunicolor Y4941, Perenniporia tenuis D5785and Schizophyllum commune Y5298. The strainswhich have the capabilities to degrade Dimethomorph are Trametes suaveolens D8888andFomes fomentarius Yang48. To Mancozeb: Fomes fomentarius Yang48and Trametesversicolor W4614. To Chlorothalonil: Funalia trogii W4289, Lenzites betulina Y4962,Rigidoporus crocatus D10146, Schizophyllum commune D9466and Trametes versicolorW4614. To Azoxystrobin: Perenniporia tenuis D10265. A lowest Chlorothalonil residue of1.92%was detected after72h degradation with the liquid culture under140r/min shakingspeed with the temperature at30°C. The amount of mycelium adsorption is0.91mg/g.(2) After72h incubation period, a highest metalaxyl removal of77.44%was observed byPhlebia sp. Y3667under140r/min, temperature at30°C and metalaxyl concentration at10mg/L. The amount of mycelium adsorption is0.56mg/g.(3)10times and100times zymolytic liquid of Cerrena unicolor Y4941and Phlebia sp.Y3667have significant growth-promoting effect to the plant height, stem diameter, leaf length, leaf width, root length, fresh weight, dry weight and water content of green bean andcucumber seedling, while the effect is not significant on corn seedling.