Effect of Low-temperature Stress on the Chlorophyll Contents and Chlorophyll Fluorescence Parameters in Muskmelon Seedling Leaves

Two muskmelon cultivars,Zaojin and Elizabeth were treated under different low-temperature(30℃/20℃,21℃/12℃,15℃/8℃,d/n),the effects on the Chlorophyll contents and Chlorophyll fluorescence parameters in seedling leaves were determined.The results indicated that under low-temperature,Chlorophyll contents was reduced with the temperature was decreased.Analysis results of Chlorophyll fluorescence parameters indicated that under different low temperature,Fv/Fm,Fv/Fo and qP decreased,but qN increased.That situation was most serious under the circumstance of 15℃/8℃.The result explain the center of PS Ⅱ activity was injured and FPS Ⅱ of light chemical reaction was declined under low-temperature.At the same time,the result explain that electronic transmition process was inhibited and electronic transmition rate was decreased in photosynthesis.