Abstract:

In order to understand the diurnal variation, characteristics of 3 dimensional distribution of Photosynthetic Available Radiation (PAR) and the size of leaf area index (LAI) on 2 kinds of shape for Korla Fragrant Pear, in the HOBOware automatic weather station and SUNSCAN canopy analysis system were used. The results showed that there were big differences of the diurnal variation of PAR in different azimuths of the 2 tree forms. A single peak curve expressed the general tendency of “low-high-low”, and the PAR of different tree forms exhibited a unstable floating. There were 2 tendencies of 3 dimensional distribution of PAR. The PAR of delayed-open central leader shape was gradually descended from upper to lower, outer to inner, and had a larger fluctuation in the upper canopy, but in the lower was opposite. The PAR of open center shape was gradually descended from inner to outer, upper to lower. The mean value of LAI in different directions of delayed-open central leader shape was all greater than these of open center shape. By compared the mean value of LAI of different tree forms in different periods, it was considered that the mean value of LAI in senescence phase was obviously greater than full fruit period.

Key words: photosynthetic available radiation, leaf area index, canopy

摘要：

为了解两种树形库尔勒香梨树冠内的光合有效辐射日变化、三维分布特征和叶面积指数大小,利用HOBOware自动气象站和SUNSCAN冠层分析系统进行测定分析。结果表明：两种树形不同方位之间的光合有效辐射日变化趋势具有较大差异,总体趋势是“低-高-低”的单峰变化曲线,不同树形辐射值表现出不稳定的上下浮动；光合有效辐射的三维分布大致呈现两种趋势,疏散分层形辐射值由树冠外围向树干内膛呈现递减趋势,由冠层下部到冠层上部递增,其冠层上部辐射值波动较大,而冠层下部则维持较低稳定水平：开心形的辐射值由冠层外围向冠层内膛递增,由树冠上层向树冠下层递减。疏散分层形的叶面积指数在不同方向上的均值显著大于开心形,同种树形在不同时期的叶面积指数均值比较认为,衰老期叶面积指数均值明显高于盛果期。

关键词: 光合有效辐射;叶面积指数;冠层