A preliminary study on adjustment of nutrient elements for allelopathic effect of Cucurbita moschata M. cultured roots

By regulating components in B5 culture media,under four concentrations(1/2 B5,B5,3/2 B5,and 2 B5) of the five necessary elements(P,Mg,Fe,Cu,and B),allelopathic effect of pumpkin root culture(Var.Jingou) filtrates on the growth of two receiving plant seedlings(Cucurbita moschata M.Var.Jingou and Var.Heizi) were studied.The results indicated that different elements showed various effects on growth of receiving plant seedlings,which depended significantly on their corresponding contents and varieties of the accepting plants.Pumpkin cultured roots filtrates exhibited marked inhibition under deficit(1/2 B5) and normal(B5) nutrient circumstance.And under enhanced nutrients conditions (3/2 B5 and 2 B5),it generally showed significant stimulation effects.Fe and B redundancy would lead to certain inhibition.On the other hand,under the most redundant environment(2 B5),B element causes strong auto-toxic effects of Var. Jingou.Meanwhile,Fe would induce inhibitory effect of Var.Jingou cultured roots on seedlings growth on seedling growth of Var.Heizi.In conclusion,it was preliminarily derived that both P and Mg elements could eliminate phytotoxic activity of pumpkin cultured roots.However,Fe,Cu,and B elements showed allelopathy regulation of pumpkin,which depend on acceptors accessions.The results of this study could provide important reference and guidance for removing the obstacles of continuous cropping by fertilizer manipulations in modern sustainable agriculture.