Comparative Analyses of Some Physiological Characters of Watermelon Seedlings under 10℃ and 15℃ Low Temperature Treatments Effects of Exogenous Proline on Nitrate Reduction in Melon Seedlings under Salt Stress Study on Growing Media pH on Growth and Photosynthetic Characteristics of Muskmelon Seedlings Effect of Calcium on Muskmelon Seedling Harmed by Acid Rain Effect of nutrient solution concentration on growth and photosynthetic characteristics of muskmelon seedling