气孔的开闭情况及在一天内的变化与果树的光合作用、呼吸作用及蒸腾作用密切相关。果树光合作用的日中低落(即“午休”现象)降低了果树的光合生产力,限制了产量的提高,其主要原因就是中午出现强烈的太阳辐射和高温低湿使叶片过热,水份代谢失调,引起气孔关闭。有研究报道苹果等落叶果树存在着明显的午休现象。本试验研究了苹果、梨、枣 Stomatal opening and closing of the situation and the changes within a day and fruit tree photosynthesis, respiration and transpiration are closely related. The low day-to-day photosynthesis of fruit trees (ie, “midday depression”) reduced the photosynthetic productivity of fruit trees and limited the increase of yield. The main reason was the intense solar radiation and high temperature and low humidity at midday, which overheated the leaves and caused the imbalance of water metabolism Stomata closed. Studies have reported apples and other deciduous fruit trees there is a clear phenomenon of lunch break. The experiment studied apple, pear, jujube