Effects of phenolic compounds on the growth of Cucumis sativus seedlings and Fusarium oxysporum hypha

This paper studied the categories and contents of phenolic compounds in greenhouse continuous cropping soil,and their effects on the growth of Cucumis sativus seedlings and Fusarium oxysporum hypha.The results revealed that with the increasing year of continuous C.sativus cropping,soil vanillic acid,p-hydroxybenzoic acid and ferulic acid accumulated gradually.The total amount of the three phenolic compounds reached 29.8 mg·kg-1 dry soil after 7 years cropping,being markedly higher than that after 1 or 3 years cropping.After treated with these compounds,the root length and stem width of C.sativus seedlings decreased markedly,but plant height and dry mass were less affected.Compared with the control,treating with phenolic compounds could promote plant POD activity within a short period,but 5 days after,the POD activity decreased again.Plant SOD activity also showed a similar up-and-down trend.High concentration phenolic compounds could continuously induce the seedlings producing MDA.Within 42 hours,the growth of F.oxysporum hypha was stimulated by low concentration phenolic acids(≤50 mg·L-1)but restrained at the concentration higher than 50 mg·L-1.With extending treated time,the tolerant ability of C.sativus seedlings to phenolic compounds enhanced,and the restraining effect of high concentration phenolic compounds on C.sativus seedling growth was not so evident.