土壤干旱胁迫对臭椿苗木生理指标的影响

Effects of Soil Drought Stress on Seedlings Growth and Physiology of Ailanthus altissima

在田间设置4种土壤含水量水平,即严重干旱、中度干旱、轻度干旱、适宜含水量(分别为田间持水量的12.5%、25%、50%和75%),研究臭椿幼苗在土壤干旱胁迫下的生长与生理响应。结果表明:在田间干旱胁迫下,随着干旱胁迫程度的增大和胁迫时间的持续,幼苗叶片的质膜相对透性、过氧化物酶(POD)活性、超氧化物歧化酶(SOD)活性、丙二醛(MDA)的量、脯氨酸质量分数等增加,净光合速率、蒸腾速率、气孔导度、瞬间水分利用效率等减小。不同处理间臭椿幼苗叶片的净光合速率、蒸腾速率、气孔导度、瞬间水分利用效率的差异均达到极显著水平(P<0.01)。臭椿幼苗能忍耐中度以下的土壤干旱胁迫。

An experiment was conducted to study the growth and physiological response of Ailanthus altissima at seedling stage to soil drought stress with four different soil water content levels： W1 （severe soil drought stress, 12.5% of the field capacity）, W2（ moderate soil drought stress, 25% of the field capacity）, W3 （mild soil drought stress, 50% of the field capacity ）, and W4 （optimal soil water content, 75% of the field capacity as CK）. The drought resistance of A. altissima was evaluated. Results showed that with the increasing of soil drought stress, the membrance permeability, POD and SOD activities, MDA content and prohne content of the seedlings increased, but the net photosynthesis （Pn）, evaporation rate （ E）, stomata] conductance （ g, ） and instant water utilization efficiency （IWUE） were reduced. The values of Pn, E, g,, and IWUE in the seedlings from different water stress treatments were significantly different （P 〈 0.01 ）. It is proved that the tolerance of A. altissima seedlings to soil drought stress is just under moderate levels.