Study On Regulation Of Plant Morphology Of Cucumber Seedling In Summer And The Particle Size Of Cultivation Substrate

In order to improve the yield and quality of cucumber,the suitable regulation of plant morphology of seedling and the proportion of grain size of cultivation substrate were screened out by using the tidal seedling system and the closed tank cultivation system of Vegetable Research Center of Beijing Academy of Agricultural and Forestry Sciencesl.The experimental variety"Jingyan 118"was used to study the effects of spraying different concentrations of CCC(100 mg·L^-1,200 mg·L^-1,300mg·L^-1)and different irrigation water temperatures（5℃,10℃,15℃）on the growth,seedling strength index and photosynthetic parameters of cucumber seedlings.The effects of different matrix particle size ratios on plant growth,root system,yield,quality and photosynthetic characteristics of closed cultured cucumber were studied.The research results of this paper are as follows:（1）Application of CCC and cold water irrigation could effectively inhibit the growth of cucumber seedlings.CCC and cold water irrigation can inhibit the growth of hypocotyl,internode length and plant height of cucumber seedlings,deepen the leaf color and increase the stem diameter.The robust seedling index and root-cap ratio under C2T2 treatment were 137.5%and 62.5%higher than those under CK treatment,respectively.It was concluded that the combined measures of spraying CCC concentration at 200 mg·L^-1and cold water temperature at 10℃had the best dwarfed and strong seedling effect in summer.（2）The perlite particle size ratio had a significant effect on the physical properties of the substrate and the growth of cucumber.The physical properties of pure small size perlite treated with T9 are the best.T9 treated cucumber had the best growth potential and root adaptability,the best quality and the highest yield.The Pn,Gs and Tr of cucumber leaves treated with T9 were the largest.T9 processing Fv/Fm,ΦPSⅡand a significant rise in q P,Fo and NPQ dropped significantly.The proportion of light energy absorbed by T9 leaves to P is the largest,and the carbon assimilation efficiency and photosynthetic capacity of cucumber leaves treated by T9 are the strongest.It was concluded that the treatment with pure pearlite ratio with small grain size（less than 2 mm）was suitable as the substrate for cucumber cultivation under closed tank culture.