采用方格法和分层法相结合的技术对江苏省如东县棉花原种场林网保护区内13年生梨园的树冠结构特征和光能分布与利用规律进行了系统研究。结果表明:梨树叶幕光能分布状况直接受叶面积系数、树冠结构、太阳位置及光强的影响。各层叶幕中的光合有效辐射(PAR)分布随自然光照条件的变化而改变,其日平均透光率大小和PAR日变化范围均从叶幕外围向内膛随累积叶面积系数(LAI)的增加而减弱;不同生长时期及不同天气变化下树冠光能分布存在明显的差异性;树冠结构与累积LAI对PAR的分布及利用率具有决定性的影响。在生产实践中,通过密度调控、整形修剪等农业技术措施,维持成年梨园盛果期高效光合生产的叶幕厚度在2.5m以上,有效LAI为4左右,是增强梨树光合生产能力、提高产量和品质的有效措施。

Using gird system and layer methods, the characteristics of canopy structure and the patterns of light distribution and utilization in the 13-year-old pear orchard conserved by forest network were studied in Ru Dong county, Jiangsu Province. The result showed that the light distribution in the canopy were obviously affected by the leaf area index ( LAI) , the structure of canopy, solar radiation and its apparent movement, etc. The light distribution in the different layers of the canopy varied with the changes of the natural sunlight, the mean daily light transmissivity and the daily changes of PAR were reduced as the accumulative total LAI increased from the external to the internal part of the canopy; There were great different in the light distribution between different development stages and different weather condition. The light distribution and the efficiency of its utilization were directly determined by the structure of the canopy and the accumulative LAI. In order to enhance the light penetration and its efficiency in the photosynthesis, it was suggested that by controlling density, training and pruning and other agricultural techniques, the thickness of the canopy of a mature, bearing tree be maintained at more than 2 . 5 m, with an effective LAI of approximately 4 .