Allelopathic effects of fresh parsley root acetone extracts on Fusarium oxysporum f. sp. cucumberinum and allelochemicals identification

In field production of cucumber (Cucumis sativus), it is relatively difficult to control wilt caused by Fusarium oxysporum. However, the extent of infection is reduced by crop rotation with parsley (Apium graveloens). To identify inhibitory allelochemicals released into the soil by parsley crop, acetone extracts from fresh parsley roots were examined after a repeated series of purification (four cycles) in column chromatography (10 mm × 300 mm) using a column with silicone coating. We used a bioassay that incorporated the various column fractions into PDA medium and co-cultured the plates with F. oxysporum f. sp. cucumberinum. By measuring colony diameter and spore germination rate, we screened the best fractions in terms of allelopathic inhibition effect and identified further allelochemicals of the fourth chromatography using GC-MS. Optimal fractions (RA3246, RA3344, RA9889 and RA91064) obtained from the fourth cycle of chromatography showed considerable allelopathic effect. The allelopathic inhibition effects of the four optimal fractions on hypha growth compared with the fourth cycle tomographic acetone (the control, ACK4) respectively were 28.69%, 37.83%, 42.44% and 33.83%, while spore germination inhibition rate were respectively 50.72%, 50.66%, 55.02% and 59.37%. Further identified were organic acids, phenols, alcohols, esters, heterocyclic organic matter, 6 forms of N compounds and 12 forms of allelochemicals in the GC-MS analysis. These included 3-Hydroxymandelic acid, thioglycolic acid, 2,4-Di-tert-butylphenoc, 2-Dodecanol, 2-Propenoicacid, 2-methyl-, tridecylester, 2-dimethylcyclohexylamine ester, dodecyl acrylate, 2-Propenoic acid, 2-methyl-pentadecyl ester, 3,4-epoxytetrahydrofuran, hexadecyldimethylamine, (Z)-octadec-9-enamide and dibutylcyanamide. The results provided the needed theoretical basis for the prevention and control of Fusarium wilt of cucumber by using extracts of parsley.