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以25a生“红富士”苹果为试材,于生长季节对饱和水分环境的离体枝条叶片与活体叶片的水势和光合作用进行了连续观测,以探索年周期内果树生长不同发育阶段叶片水分状况对光合作用和水分利用效率的影响。结果表明:在“红富士”苹果生育期前半阶段的展叶抽梢期、开花坐果期、花芽分化期,由于尚未进入降雨季节,叶片水势不断下降,光合速率和蒸腾速率都明显小于离体枝条叶片,叶片水势的降低在一定程度上限制了蒸腾速率,但是也同样降低了光合速率,导致水分利用效率逐渐下降。因此在4~5月份抽梢展叶期和开花坐果期应当及时进行灌水补充,6月份适度的水分胁迫则有利于花芽分化。在7、8月份冠层蒸腾作用强烈,叶片的水势下降明显,此时的水分胁迫限制了蒸腾速率,提高了水分利用效率。由于此期已经进入雨季,除个别干旱年份以外,通常无需灌溉。在9月份以后进入果树生长发育后期,随着日照时数和气温逐日下降,活体叶片的光合速率和蒸腾速率与离体枝条叶片的差异变小,树体的水分利用效率提高,一般不予灌溉。
Taking 25a green “Red Fuji ” apple as test material, the water potential and photosynthesis of detached shoot and live leaves in saturated water environment were observed continuously in the growing season to explore the growth of fruit trees at different developmental stages Effect of Water Status on Photosynthesis and Water Use Efficiency. The results showed that in the first half of the growth period of “Red Fuji” apple, the flowering and setting stages and flowering and bud differentiation stages had no significant effects on the leaf water potential and the photosynthetic rate and transpiration rate. The decrease of leaf water potential in body branches and leaves has limited the transpiration rate to a certain extent, but also reduced the photosynthetic rate and decreased the water use efficiency. Therefore, from April to May, leaf-setting and flowering stage should be timely supplemented with irrigation. Moderate water stress in June is conducive to flower bud differentiation. In July and August, there was strong canopy transpiration, and the water potential of the leaves decreased significantly. At this time, the water stress limited the transpiration rate and improved the water use efficiency. Since this period has entered the rainy season, irrigation is usually not required except in individual drought years. After entering the late growth and development stage of fruit trees after September, the difference of photosynthetic rate and transpiration rate of live leaves with that of in vitro shoots became smaller as the sunshine duration and temperature dropped day by day, and the water use efficiency of trees was increased. .