土壤干湿交替对青檀幼苗生理及生长的影响

采用盆栽试验人工模拟喀斯特地区常见的干湿交替环境,研究青檀幼苗生理和生长指标的变化以及旱后复水的恢复能力.结果表明,干湿交替环境下幼苗各项生理指标的变化因干湿交替处理次数而异.经过1次干湿交替处理的幼苗叶片水分饱和亏缺,根和茎木质部水势,叶片光合速率、蒸腾速率,叶片质膜透性等指标变化剧烈,2次处理变化相对缓和,而3次处理变化幅度又加大,这反映了幼苗从反应、适应到不适应的过程.干旱复水后,各项指标的恢复度与干湿交替处理次数呈负相关.恢复过程中补偿效应普遍存在,尤其以生长上的补偿效应最明显,这是幼苗对反复干旱-复水环境的一种适应策略.干湿交替处理对生长初期青檀幼苗生理指标的影响大于速生期,对生长指标的影响则相反.因此,速生期幼苗遭遇反复的干旱-复水处理会严重制约其生长潜力的发挥.

Effect of Soil Drying-Wetting Alternation on Physiology and Growth of Pteroceltis tatarinowii Seedlings

The spot experiments of Pteroceltis tatarinowii seedlings were carried out by simulating soil condition of drying-wetting alternation similar to karst region.The variation of physiological indexes,growth indexes and the restoration ability of seedlings after re-watering were studied.The results showed that the variation of physiological indexes was different with the times of soil drying-wetting alternation.The variation of water saturation deficit,xylem water potential of root and stem,net photosynthetic rate,transpiration rate,leaf plasm membrane permeability of seedlings changed greatly at one cycle,and relatively stable at two cycles,but the variation enlarged again at three cycles.These changes reflected a process from the reaction,and adaptation to inadaptation of the seedlings to soil drying-wetting alternation condition.After re-watering,the restoration degree of these indexes had a negative correlation with the cycle times.The compensatory effect was common in the restore process,especially for growth indexes,it is an adaptative strategy of seedlings to soil drying-wetting alternation condition.The effects of soil drying-wetting alternation on physiological indexes of P.tatarinowii seedlings were more serious at the early growth stage than at the rapid growth stage,but for the growth indexes were contrary.Therefore,the growth potential of seedlings would be restricted by repeated drying-wetting alternation condition at the rapid growth stage.