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In this study, two melon cultivars in Xinjiang early gold Elizabeth as test material, the use of artificial climate chamber (RXZ, Ningbo Jiangnan Instrument Factory manufacturing) a temperature-controlled way, three temperature conditions (30 ℃ / 20 ° C (day / night, the same below), 21 ° C / 12 ° C, 15 ° C / 7 ° C) of two muskmelon seedling growth and physiological and biochemical characteristics, in order to reveal the physiological and ecological differences between different melon varieties for breeding low temperature resistant varieties and identification methods provide a theoretical basis. The main results are as follows: 15 ° C / 7 ° C, muskmelon seedling growth was inhibited seedling height, plant and leaf area, dry matter accumulation increased slowly, chlorophyll content decreased with the low temperature prolonged duration; 15 ℃ / 7 ℃ under processing 10d, as early as gold in leaves serious loss of green, yellow, yellow growing point, individual plants died; the seedling leaves Elizabeth mild symptoms; melon seedling growth inhibition of less than 15 ° C in the 21 ° C / 12 ° C / 7 ° C , the temperature inhibit the growth of early payment than the heavier inhibition of Elizabeth; 30 ° C / 20 ° C conditions caused early as gold seedlings newborn leaves thin and small, petiole and internode length, and Elizabeth seedling growth had no effect. The low temperature of the early gold seedlings growth inhibition is stronger than that of Elizabeth. Two varieties in the temperature of the root activity over time extension of the first and then decreased trend. Proline, soluble protein and soluble sugar trend with the temperature gradient of the decline and rise, and rise with the duration of the extension now dropped. 15 ℃ / 7 ℃, proline and soluble sugar were significantly higher than 30 ° C / 20 ° C, 21 ° C / 12 ° C conditions. The contrast between the two varieties of data can be drawn Elizabeth indicators over as early as gold, Elizabeth, more tolerant of low temperature stress. Than 30 ℃ / 20 ℃, 21 ° C / 12 ° C and 15 ℃ / 7 ℃ caused two the melon varieties of seedlings light compensation point, elevated CO2 compensation point, light saturation point, reduce CO2 saturation point low temperatures reduces the the melon seedlings photosynthetic capacity and CO2 utilization range; two leaves of 15 ℃ / 7 ℃ stomatal conductance, transpiration rate, stomatal limitation, water use efficiency, instantaneous photosynthetic efficiency than 20 ° C / 12 ℃, 30 ℃ / 20 ℃ significantly decreased but intercellular CO2 increased, indicating that the reasons for the decline in net photosynthetic rate of the the melon seedlings under low temperature stress non-stomatal limitation. Low temperatures Fv / Fm and Fv / Fo significantly reduce reflect the low-temperature stress so that the melon leaves light system Ⅱ (PS Ⅱ) active center damaged; Chilling Stress can also affect the melon seedlings of qP and qN, performance for qP the decline and qN elevated. The qP reduced QA re-oxidation of reduced capacity, decreased activity of PS II electron transport; the qN rise melon seedlings by the dissipation of excess energy to protect the photosynthetic apparatus from chilling injury enhancement. 4 cell membrane permeability, MDA content and SOD, POD, CAT activity as muskmelon seedling cold tolerance identification basis. Low temperature stress melon seedlings relative membrane permeability increased MDA levels increased significantly increasing trend over time, under the conditions of 15 ℃ / 7 ℃. Presents the trend first and then decreased processing time, as the temperature decreases and extend the duration of the two varieties of SOD activity, POD activity showed a tendency to increase, while CAT contrary show a downward trend. Under various temperature conditions, Elizabeth membrane permeability, MDA content and SOD, POD, CAT activity were lower than early payments. Elizabeth patience cryogenic, stronger than the ability to adapt to the low temperature early as gold, can be used as one of the facilities in winter and spring melon cultivation of suitable varieties. In summary, the cryogenic great impact on melon seedling growth and physiological activities, the study confirmed that 15 ° C / 7 ° C conditions and longer duration of 21 ℃ / 12 ℃ conditions will affect the growth of the melon. -Season production should be to select the low-temperature-resistant varieties to develop technical solutions to the premise, the low temperatures encountered in the production process, should pay attention to the use of the facility has controllable and adjustable performance given insulation warming.
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