干旱胁迫对苏北沙质海岸3个树种水分光合生理特性的影响

Effects of Water Stress on Water Photosynthetic Physiology Characteristics of Three Tree Species in Sandy Shores of Northern Jiangsu Province

[目的]为了了解苏北沙质海岸3个造林树种的耐旱能力,为沿海防护林体系建设提供理论依据和技术支持。[方法]通过盆栽苗木水分胁迫试验,着重分析了在水分胁迫条件下榉树、弗吉尼亚栎、女贞2a实生苗的水分生理和光合作用日变化特征。[结果](1)随时间推移和胁迫程度加强,3个树种的叶片相对含水量均呈递减趋势,榉树的下降幅度高于女贞和弗吉尼亚栎;胁迫58d的重度水分胁迫处理下,3个树种相对含水量分别比对照下降了78.8%,61.9%和65.5%,弗吉尼亚栎和女贞的相对含水量变化较小;(2)3个树种叶片净光合速率日变化曲线在CK,60%和45%含水量条件下均呈双峰型;在正常和轻度水分胁迫下,弗吉尼亚栎蒸腾速率和气孔导度表现出双峰特征,而榉树和女贞则为:典型的单峰曲线;随着胁迫程度加强,3个树种的净光合速率、蒸腾速率、气孔导度和水分利用效率的日均值均为:CK>60%含水量>45%含水量>30%含水量;同一水分条件下,4个指标的日均值呈现出:榉树<女贞<弗吉尼亚栎的规律。[结论]3个树种的抗旱能力由强至弱依次为:弗吉尼亚栎>女贞>榉。沿海防护林的建设中应优先选择弗吉尼亚栎。

[Objective] To study the drought tolerance of three afforestation trees on the sandy shores of Northern Jiangsu Province. [Methods] Based on the experiment of water stress in pots, the index variation of water physiological characteristics and daily dynamics of photosynthetic characteristics of 2-year-old Zelkova schnideriana, Quercus virginiana and Ligustrum lucidum under water stress were analyzed. [Results] （1） With time and stress intensity increasing, the relative water content in leaves of the three tree species all decreased, and the decreasing range of Zelkova schnideriana was bigger than that of Quercus virginiana and Ligustrum lucidurn; water content of the three tree species decreased by 78.8%, 61.9% and 65.5% under severe water stress of 58 days, and the relative water contents of Quercus virginiana and Ligustrum lucidum changed a little. （2） Under treatments of CK, 60% and 45% water content, the diurnal curves of the photo- synthetic rate of the three tree species were ＂double-peak＂. Under normal and light water stress, the diurnal curves of the transpiration rate and stomatal conductance of Quercus virginiana were ＂double-peak＂, while the same curves of Zelkova schnideriana and L igustrum lucidum were ＂single-peak＂. With increasing stress, the order of Pn, Tr, Gs and WUE of the three tree species was： CK〉60% water content〉45% water content）30 % water content. In the same soil water grades, the daily averages of the four indexes of Zelkova schnideriana were relatively small, followed by Ligustrum lucidum, whereas those of Quercus virginiana were the largest. [Conclusion] The drought tolerance characteristics of Zelkova schnideriana were relatively small, followed by Ligustrum lucidum, whereas those of Quercus virginiana were the largest.