调亏灌溉对香梨叶片光合速率及水分利用效率的影响

Photosynthesis Rate and Leaf Water Use Efficiency of Korla Fragrant Pear Tree under Regulated Deficit Irrigation

试验研究了调亏灌溉对成龄库尔勒香梨树叶片生理指标的影响。在果实快速膨大前期分别施加了2种水分胁迫:轻度水分胁迫,灌水量为蒸发量的60%;重度水分胁迫,灌水量为蒸发量的40%。在果实快速膨大期,灌水量为蒸发量的80%。对照处理为香梨的整个生育期灌水量均为蒸发量的80%。结果表明,调亏灌溉期间,水分胁迫显著地降低了香梨树的叶片光合速率、蒸腾速率与气孔开度;果实快速膨大期,调亏处理恢复充分灌后,叶片光合速率、蒸腾速率及气孔开度均在一定程度上恢复,轻度调亏处理恢复到与对照相同的水平,而重度的水分胁迫处理却始终低于对照。叶片蒸腾速率比光合速率对土壤水分变化更敏感,水分胁迫可提高香梨树的叶片水分利用效率。

The experiment was conducted to study the effects of regulated deficit irrigation on these parameters of the Korla fragrant pear tree. The water deficit applied before the fruit enlargement stage included ： slight water deficit, the trees were irrigated with 60% of US Class A pan evaporation （Ep）; severe water deficit, the trees were irrigated with 40% of Ep. During the fruit enlargement stage, both water deficit treatments were irrigated with 80% of Ep. The control was irrigated with 80% of Ep during the whole growth season. The results indicated that the leaf photosynthesis rate, transpiration rate and stomatal conductance were significantly reduced by the soil water deficit. After full irrigation resumed, the leaf photosynthesis rate, transpiration rate and stomatal conductance restored rapidly to some extent, the physiological parameters of slight water deficit reached the control level in the middle August, however, those of the severe water deficit were always lower than the control. As compared with the photosynthesis, the transpiration was more sensitive to the soil water deficit, resulting in the improvement of the leaf water use efficiency