Changes of photosynthetic characteristics of cucumber leaves during unfolding in solar-greenhouse

不同时期黄瓜叶片的展开速度有较大差异。10月14日伸出叶片的叶面积35 d时达到最大，12月1日伸出叶45 d时才完全展开，且其最大叶面积明显小于10月14日伸出叶。2月1日伸出叶的叶片展开速度与最大叶面积介于10月14日和12月1日伸出的叶片之间。各时期叶片的色素含量于叶片展开前期逐渐升高，20～30 d后下降。随着叶片展开程度的增加，各时期伸出叶片的Pn逐渐增加，20 d左右时达到最大值，然后逐渐降低。光饱和点和补偿点多随叶片伸出时间的延长而降低。AQY变化曲线呈单峰型，高峰分别在叶片伸出后20～40 d出现。CE于叶片伸出20～30 d时达到最大，升降速度以10月14日伸出叶的最快，12月1日的最慢。叶片伸出前期，Fv/Fm和фPSⅡ随叶龄增大而增加，40～50 d时开始下降。叶片初展时，气孔与非气孔因素同时影响叶片的Pn；而叶片衰老时，光合功能的衰退主要与叶肉因素有关。 Changes of photosynthetic characteristics of cucumber leaves during unfolding in solar-greenhouse were studied. The results showed that the unfolding rate of cucumber leaves at different stages was different obviously. The leaves unfolded at quicker speed in Oct.-Nov., and the leaf area was the largest on 35 d after leaf came out. While those of Dec. 1 leaves on 45 d, and their largest leaf area were less than those of Oct. 14 leaves. The unfolding rate and the largest leaf area of the leaves which came out on Feb. 1 were among those of leaves came out on Oct.14 and Dec. 1. The pigment content of leaves at different stage