The Research On The Damage Mechanism Of Hypothermia And Low Light To Cucumber And The Inductive Resistance Of BR

Temperature and illumination are necessary for plants' growth. In the process of vegetable's off-season cultivation, the lacks of temperature and illumination are the main obstruction of production increasing, quality improving and profitable agriculture increasing. This experiment choose cucumber, one kind of the main vegetables in modern greenhouse cultivation,as experiment material.And this experiment contains two parts.First,based on the experiment methods and achievements and cultivated in greenhouse,analog low temperature and light environment in greenhouse by ventilating for cooling and heating temporarily which is very common in vegetable's production in spring and winter.discussing its growth characteristics and adaptation mechanism in those aspects of form,photosynthesis,output and quality,the main purpose is providing theoretical basis for cucumber's cultivation and breeding work under low temperature and light.Then,considering the effects of low temperature and light on cucumber's growth,output and quality in its cultivation,study the control action of BR for cucumber's resistance on low temperature and light,in order to provide theoretical basis for agriculture production.The main results are as follows:1. Low temperature and low light might affected observably growth, production and quality of cucumber(1) Under the temperature and light setted in this experiment,it is clearly impacted in stem length and diameter,leaf area and dry matter. With the different temperatures and the same light intensity, stem length and diameter, leaf area and dry matter are declined clearly.with the temperature declined;with the same temperature,stem length,leaf area and dry matter are increased with light intensity declined,but stem diameter is declined. The longer treatment time,the more clearly the effects are.(2) Under the low temperature and light treatment,Pn,Tr,Gs and Ci of all treatment are declined clearly.But the photosynthesis characteristics of the six treatments have different performance between each other,the photosynthesis of lvdao No.1,fengguan No.3 and shuchun new transcend don't show clearly decline under low light.(3) Under the same light intensity and different temperature,the output of all treatment are declined when the temperature is declined;under the same temperature,the output of all treatment are declined when the light intensity is declined,but not clearly.The effects of low temperature on cucumber output are more clearly than low light,and different species shows different performance.(4) In this experiment,the quality of cucumber has been greatly effected.With the same light intensity and different temperature,the contents of soluble protein and organic acids are increased with temperature declined.but soluble solids,soluble sugar and the content of vitamin c are on the contrary;with the same temperature,the contents of soluble protein,organic acids and soluble sugar are increased not clearly when the light intensity is declined,the contents of vitamin c and soluble solids are declined.2.The adaption of different kind of cucumber production to hypothermia and Low Light. The production of South China type cucumber is lower than that of north china. The adaption to low light of "Jiza No.4" cucumber is better than the others, and the adaption to hypothermia of "ludao 1" cucumber is better than the others among the south china cucumber type. The adaption to certain low light and hypothermia of "shu chun xin chao yue" cucumber is better than the others among the north china cucumber type. In conclusion, the adaption of "fengguan No.3" cucumber to hypothermia, low light and the combination of the 2 factors is better than the others. So it is suggested to plant in native.3.Exogenous brassinolide might remitted injuries of cucumber under low temperature and light stress In the same experiment time,use different contents of BR inducing the cucumber seedlings,in order to discuss the effects of BR for cucumber seedlings on resisting low temperature and light in the drop back into grow time under the low temperature and light.As a result,no matter before the stress with low temperature and light or not,the activity of antioxidant enzymes,the content of chlorophyll are increased and the content of MDA is declined with the BR treat.However,the injury of cucumber can be reduced under the stress of low temperature and light.