Research Of Grafted Cucumber (Cucumis Statirus L) Replant Problem

Cucumber (Cucumis statirus L.) is the favorable vegetable for Chinese and has become the main variety of greenhouse vegetables. However, the contradiction between limited land and market supply all yearlong resulted in the fact that continuous cropping obstacles become common and serious more and more. Allelopathy is one of the most important factors of continuous cropping obstacles. At present, cucumber is cultivated in greenhouse generally by grafted with squash as rootstock. But systematic research concerning continuous mono-cropping grafted cucumber obstacle isn't reported. This paper systematically studied the effect of continuous cropping soil on grafted cucumber in aspect of its growth, yield and edaphon in pot experiments. Further more, root exudates of squash and grafted cucumber were collected by solution cultivate and adsorption of XAD-4 resins, and bioassay of the root exudates was did with cucumber and squash as receptors, studied allelopathy of grafted cucumber and squash root exudates on cucumber and squash , physiobiochemistry as well as. It is significant to production of greenhouse vegetable in reason, improving and adjusting existing disadvantageous cultivated measures of protected cucumber. The main results are as follows:In the seedling period, long-term continuous mono-cropping grafted cucumber isn't worse than no-replanting grafted cucumber in height of plant, number of the leaves, diameter of stem, number of the roots, diameter of the root and the area of the leaves. However, in the late stage of growth, long-term continuous mono-cropping grafted cucumber is significantly worse than short-term continuous mono-cropping and no-replanting grafted cucumber in these aspects, and in water use, biomass, economic yield , photosynthesis and the content of chlorophyll gained similar result. In the research about the effect of continuous cropping on protective enzyme of grafted cucumber, though superoxide dismutase, peroxydase and catalase have different representation, after continuous mono-cropping for 6 years or more earlier, their activity significantly decrease. So long-term continuous mono-cropping soil lead to continuous cropping obstacle of grafted cucumber, short-term continuous mono-cropping soil don't bring this result.The respiratory rate of continuous mono-cropping soil of grafted cucumber decreased with increase of the number of years. So this show the total and activity of microbe in soil decreased with increase of the number of years. The species of microbe in soil also have changed with increase of the number of years, and bacteria and fuggi increased with increase of the number of years, but actino myces decreased with increase of the number of years. So worked resistance decrease of grafted cucumber.Grafted cucumber and squash root exudates have the inhibitory effect of germination of cucumber, elongation of root and hypocotyls, and have the same effect on squash. This effect have a direct correlation with the concentration of root exudates. and found root exudates have the promotable effect on the activity of IAAoxidase of cucumber and squash, .So explaining it can reduce the IAA of them, accordingly restrain the growth of them. And root exudates restrain the activity of amylase of cucumber and squash. This inhibitory effect also have a direct correlation with the concentration of secretion of grafted cucumber root.