Studies On Alleviating Cucumber Continuous Cropping Obstacle By White-rot Fungus

In this article we use PHanerochaete chrysosporium to biodegrade pHenolic acids in the soil on site. We studied the relationships between the decreases of pHenolic acids amount and the cucumber growth condition and cucumber disease index. We also studied the effects of autotoxins on cucumber continuous cropping obstacle and provide the theory supports to discover the origin reason of cucumber continuous cropping obstacle.On the foundation of single factor experiment, we used the orthogonal array to optimize the PHanerochaete chrysosporium growth conditions in the soil. Instant nutrition, H₂O₂, inoculation amounts and sawdust were selected as the four factors of orthogonal array and each factor was divided into three levels. The orthogonal test indicated that, the optimal levels combination of the four factors on PHanerochaete chrysosporium CFU was A₁B₃C₂D₃ . The optimal levels combination of the four factors on PHanerochaete chrysosporium MnP enzyme activity was A₂B₃C₃D₁, and the LiP enzyme activity was A₃B₂C₃D₃.According to the comprehensive analysis, we determined the optimal levelscombination was A₃B₃C₂D₁ . In addition, should maintain the soil pH within 7-8, soilwater content scope 10-20%, soil temperature 20-28℃ .The total amount of three pHenolic acids, vanillic acid, p-hydroxybenzoic acid and ferulic acid, declined 54.34% after two months when the solid PHanerochaete chrysosporium was inoculated to the soil with continuous cropping obstacle. Of the three detected pHenolic acids, ferulic acid showed the highest degradation rate of 50.93%. Though there was a little improvement in cucumber seedlings height (at two leaves stages), stem width, fresh and dry weight in the bioremediation field plot, the increment was not so significant. However, we found evident alleviation of cucumber root diseases, the disease severity of wilt and root knot nematode declined 10.2% and 14.6% respectively.