干旱胁迫对三峡库区消落带桑树生长的影响

Effects of Drought Stress on Growth of Mulberry （Morus alba L. ） Trees in the Hydro-Fluctuation Belt of the Three Gorges Reservoir Area

在温室条件下模拟三峡库区消落带夏季伏旱时土壤水分变化特征,以盆栽桑树为材料,设置对照(CK)、中度干旱胁迫(T1)和特大干旱胁迫(T2)3个含水量梯度,研究了不同程度干旱胁迫对桑树生长的影响。结果表明:1)随着干旱胁迫的加剧,桑树的株高、地径和根表面积逐渐降低,差异显著(p<0.05);根冠比在处理初期逐渐升高,而后期逐渐降低;比根面积总体呈上升的趋势,差异显著(p<0.05)。2)随着处理时间的延长,各处理组的株高、地径、根表面积以及根冠比呈不同程度的上升趋势;比根面积基本上呈逐渐降低的趋势。研究结果表明,在不同程度的干旱胁迫条件下,桑树的生长受到一定程度的抑制,但能够通过合理调节自身生物量的配置,以增强吸水能力,减轻干旱伤害,维持植物体的正常生长,从而表现出一定的抗旱耐旱潜力。

To examine possible effects of soil water conditions in summer in the hydro-flue.tuation belt of the Three Gorges Reserw）ir Area on mulberry, we grew potted muberr in a greenhouse under three soil water regimes designed to simulate normal irrigation （ CK） , moderate drought stress （ TI ） and elevated drought stress （T2）. The results showed the fillowing. 1） With drought stress increasing, the heights, base diamelers, and root surface areas of mulber trees decreased signifi- cantly relative to the corresponding earlier period. The fontshoot ratio increased gradually in the earlier stage, and decreased gradually in Ihe later stage. The specific root area of mulberry trees on the whole increased significantly relative to the corresponding earlier period. 2） With the elongation of treatment time, the growth of mulberry seedlings decreased gradually, and the heights, base diameters, root surthce area and root/shoot ratio of the nmlberry trees in the three treatment grnt,ps increased to different degrees. Tie specific not area of mulbertw trees on the whole decreased gradually. We eoncluded that under the different degrees of drought stress the grwth of mulberry trees would be inhibited, but the plants were also able to adapt to tie stress, thely maintaining physiological and metabolic viability. Biomass appeared to be re-allocated such that waler absorption capacity was improved. Accordingly it can be eonclnded that the mulbeny trees demonstrated potential for resisting and tolerating drougbt stress.