‘富士’苹果不套袋与套袋密度对树体光合特性的影响

为进一步探讨不套袋与套袋对苹果品质影响的机理,以8年生‘富士’苹果（‘天红2号’/‘M26’/八棱海棠）为试验材料,共设5个套袋密度处理（不套袋、套袋1/3的果实、套袋1/2的果实、套袋2/3的果实、套袋所有果实）,所用果袋为小林果袋（双层纸袋,内红外棕）,研究不同套袋密度对果实套袋前（6月19日）、套袋后2天（6月21日）、套袋中（8月22日和9月27日）、摘袋后2天（10月9日）和采收后1天（11月3日）苹果叶片光合特性的影响。结果表明,套袋不仅降低了苹果树冠层内的光照强度,而且显著降低了叶片的光合速率,而随着套袋密度的增加,苹果树冠层内的净光合速率显著降低,尤其是在8月和9月。5个处理的冠层光强、气孔导度、叶绿素含量、类胡萝卜素含量和叶片比重的变化与净光合速率的变化基本一致,说明果实套袋导致叶片光合性能下降。套袋苹果光合速率的降低是由气孔导度的降低引起的,这可能与光照强度降低有关;而在9月光合速率的降低还可能与高温弱光,套袋苹果叶片出现非气孔限制有关。

Effects of No-Bagging and Bagging Density on Photosynthetic Characteristics of ‘Fuji’ Apple Trees

To explore the effects of fruit bagging on apple quality, eight-year-old red ‘Fuji’ apple trees (‘Tianhong 2’/‘M26’/Malus× robusta) were used as experimental materials, and five treatments (no-bagging, bagging 1/3 of all fruits, bagging 1/2 of all fruits, bagging 2/3 of all fruits and bagging all fruits) were set up. The Kobayashi fruit bags (double layer paper bag, inner red and outer brown) were used in all treatments. The effects of different fruit bagging densities on photosynthetic characteristics of tree leaves were studied before fruit bagging (June 19), 2 days after bagging (June 21), during bagging (August 22 and September 27), 2 days after bag removal (October 9) and 1 day after harvest (November 3). The results showed that bagging not only decreased the light intensity within the apple tree canopy, but also significantly reduced the photosynthetic rate of the leaves, while the net photosynthetic rate within the apple tree canopy significantly decreased with the increase of fruit bagging density, especially in August and September. The changes of the light intensity in the canopy, stomatal conductance, chlorophyll content, carotenoid content and specific leaf weight of leaves in the five treatments were basically consistent with the change of net photosynthetic rate, suggesting that fruit bagging could lower the leaf photosynthetic performance. Our experiments also indicated that the decrease of photosynthetic rate was caused by the decrease of stomatal conductance and this might be associated with the decrease of light intensity, while in September, the decrease of photosynthetic rate might also be related to high temperature and weak light intensity, and non-stomatal limitation in leaves of bagged apples.