关键词: 光合有效辐射;叶面积指数;冠层

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