锦橙树冠光能分布对光合效应与结实的影响

EFFECTS OF LIGHT DISTRIBUTION IN THE CANOPY ON PHOTOSYNTHETIC EFFICIENCY AND FRUIT SETTING IN "JINCHEN" ORANGE (Citrus sinensis) TREES

锦橙树冠内各部位光能分布差异显著。光照对光合效应、结果和果实品质有明显的影响。在重庆地区11:00～11:30时,相对光照率南部>东部>西部>北部,15:00～5:30时则南部>西部>北部>东部。全天光强度均为叶幕外层>内层>树冠中心,叶幕上层>中层>下层。净光合速率、光合产物输出率及产量与光照有相似的变化趋势。各方位不同高度叶幕层的着果率与相对光照率呈极显著正相关。中层单果重分别比上、下层果高10%～26%和20.5%～52.9%。果实 Vc 含量,叶幕中层>上层>下层。固形物含量与光照率变化势相似。可食率、果酸变化与单果重相反。

Significant differences were noticed in light distribution at different locations in the canopy of sweet orange(Citrus sinensis,cv.“Jinchen”)trees.Light intensity.appeared to have great influence on photosynthesis,fruit yield and fruit quality of the tree.From 11: 00 to 11:30 a.m.,the sunshine was directly on the southeast of the tree canopy with the “relative light received rate”being in the order of south>east>west>north while from 3:00 to 3:30 p.m.,another order of light intensity distribution was observed:south>west>north>east.The daily average light intensity appeared in the or- der of outer part of the canopy>inner part of the canopy>central part of the tree crown and Upper part>middle part>lower part of the canopy.The patterns of variation in net photosynthtic rate,photosynthate export rate and fruit yield were significantly correlated with fruit setting,the correlation coefficient r being in the range of 0.9425**to 0.9997**. Average fruit weight in the middle canopy layer was 10%～26% and 20.5%～52.9% great- er than that in the upper and lowerparts of the canopy,respectively.Ascorbic acid content in the fruit also varied with different locations within the canopy,the pattern being middle layer>upper layer>lower layer.The variation in total soluble solids followed a similar pat- tern to that of“relative light received rate”while acid content showed an opposite pattern.