分根交替不同灌水量对苹果生长和叶片生理特性的影响

Effects of Partial Root Zone Alternative Irrigation on Growth and Leaf Physiological Characteristics of Apple Trees

【目的】在确保苹果树体正常生长情况下,探讨不同根区体积灌水及灌溉量对树体生长和叶片生理特性的影响,以期提高水分利用效率,节约灌溉水。【方法】以3年生盆栽分根皇家嘎拉苹果为试材,研究根系分区交替灌溉不同水量对苹果树体生长和叶片生理特性的影响。【结果】1/4和2/4根区体积灌水显著抑制了苹果新梢和干周生长,随灌溉体积增加抑制作用逐渐解除,减少灌水量也显著抑制了新梢生长。根系分区交替灌水显著影响苹果叶片水势和气孔阻力,1/4和2/4根区体积灌水处理叶片水势显著低于3/4和4/4处理,气孔阻力随灌水体积增加显著降低。减少根区灌水部位降低了苹果叶光合速率、蒸腾作用和气孔导度,并且蒸腾作用降低的幅度显著大于光合作用的,从而提高了叶片水分利用效率。但减少灌水量对苹果叶片各项生理指标均没有影响。不同生长期根区交替灌水处理对叶片光合速率、蒸腾速率、气孔导度和水分利用效率的影响一致,以春梢停长期各生理特性指标最高。【结论】灌水量是影响新梢伸长生长和主干加粗生长的主要因子,叶片生理特性主要受灌水部位调控。通过调控灌水量和根区灌水部位可以调控树体生长,并能节约灌水量。本试验中,在没有考虑自然降水的情况下,为保证植株的正常生长,根区灌溉体积不能小于50%。

[Objective] To decrease the amount of irrigation and increase water use efficiency in apple orchard by improving the irrigation methods on the condition of maintaining the natural growth rate of apple trees. [Method] Effects of partial root zone alternative irrigation on growth and leaf physiological characteristics of three-year old roots of potted Gala apple trees were investigated in this study. [ Result ] Growth of new shoots and trunk diameter were retarded by the treatments of 1/4 and 2/4 root zone irrigation significantly, and that were released by increasing root zone irrigation. Leaf water potential and stomatal resistance were affected by partial root zone alternative irrigation, leaf water potential of 1/4 and 2/4 root zone irrigation was lower than that of 3/4 and 4/4 treatments, and stomatal resistance decreased with the amount of irrigation increasing significantly. Net photosynthetic Rate （Pn）, transpiration rate （Tr） and stomatal conductance （Gs） of apple leaves decreased with root zone irrigation decreasing, and the extent of decreasing of transpiration rate was significantly larger than that of net photosynthetic rate, therefore, water use efficiency （ WUE ） increased. However, Pn, Tr and Gs of apple leaves were not affected by the amount of irrigation. At different growth stage, partial root zone irrigation had the same effect on Pn, Tr, Gs and WUE of apple leaves, while the highest value was shown at spring shoot growth stage. [ Conclusion ] Irrigation rate was the major factor affecting the growth of new shoots, however, leaf physiological characteristics were regulated, by root zone irrigation. To maintain formal growth and development of apple trees, the root zone irrigation should not less than 50% of total root zone, the precipitation is not considered.