| Muskmelon planting is a developing style in greenhouse for these years, which represents an important effect on innovating agricultural structure and improving rural economy in Xinjiang of China. Hence, it is indispensable to frame technique project of melon planting that researching how the chilling influence growth of muskmelon and how muskmelon respond to chilling in order to acclimatize itself to it. Zaojin and Elizabeth, Muskmelon seedlings(Cucumismelo L)of two cultivars of Xinjiang's leading planting as material were treated under different low-temperatures (30℃/20℃,21℃/12℃,15℃/7℃,d/n) in this study to research seedlings growth and on physiological & biochemical properties in seedlings leaves. The results weresummarized as following:1. Low temperature can inhibit height, the area of total leaves, fresh weight of the part above & under the ground, R/T, root vigor and dry weight accumulation of Muskmelon seedlings, the inhibitions of 15℃/7℃areserious than those under the other temperatures. Though height, the area of total leaves, fresh weight of the part above & under the ground of Elizabeth seedlings are lower than Zaojin seedlings, the R/T ratio, root activity and dry weight accumulation of Elizabeth are higher than Zaojin. It suggested that Elizabeth has stronger endurance to low temperature than Zaojin.2. The root activities of both cultivars increased at first and then decreased under any temperature. Praline, soluble sugar and soluble protein increased with the temperature decreased. The condition of 15℃/7℃, praline and soluble sugar were obviously higher than other condition of 30℃/20℃and 21℃/12℃. From the result of copare with two cultivars'date , we may discern all indexes of Elizabeth was higher than Zaojin.The results demonstrated Elizabeth have more harier than Zaojin.3. Under low-temperature(15℃/7℃) the net photosynthetic rate (Pn),evaporation rate (Evap.), stomatal conductance (Gs),and chlorophyll fluorescence kinetics parameters such as Fm, Fv, Fv/Fm , Fv/Fo,FPSⅡof leaves decreased, while the thermal energy dissipation rate and photosynthetic limitation increased. The intercellular CO2 concentration(Ci) was higher than it under the other two temperature. The cause of reduction of Pn in muskmelon seedling leaves under low-temperature might be mainly non-stomata limitation. The results also suggested that chloroplast were injured by 15℃/7℃in long-term treatment. Elizabeth has more stonger photosynthesis than Zaojin under low-temperature.4. It suggested that the membrane permeability, MDA and activity of SOD, CAT, POD can be used as target for identifying cold- tolerance cultivars. The membrane permeability and MDA increased in both culivars with the decrease of temperature . Under the condition of 15℃/7℃MDA was conspicuously high.With the temperature decreaded and the time prolonging , the activity of SOD and CAT were decreased, then POD activity was increased.All of every condition, the membrane permeability, MDA and activity of SOD, CAT, POD of Elizabeth were lower than Zaojin.5. Elizabeth has stronger ability to endure low temperature, which can be selected as one of the cultivars for muskmelon planting in greenhouse.In conclusion, low temperature would damage muskmelon seedlings. For anti-season planting in greenhouse, it is very important that establishing technique project of melon planting based on selecting chilling- tolerance cultivar. It is also very important that improving temperature to avoid chilling-damage occurrence on muskmelon seedlings.
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