高温干旱复合胁迫及复水对刺槐幼苗水分运输的影响

The combined stress of elevated temperature and drought and rewatering on water transportation of Robinia pseudoqcacia Linn. seedling

近年来,随着全球变暖,部分地区干旱情况加重,且高温干旱同时发生的概率增加,对植物的生长与分布产生重要影响。采用室内模拟方法,研究高温干旱复合胁迫对刺槐幼苗水分运输的影响。主要结果表明:随胁迫程度增加,比导率(K_s)、导水率(K_h)下降,刺槐幼苗水分运输受阻,40℃下田间持水量40%时K_h、K_s仅为对照的3.6%和5.3%;气孔导度、蒸腾速率则在33℃下田间持水量70%时达到最大,40℃下田间持水量40%时有所下降但仍高于对照;复水后的补偿效应随胁迫的增加而降低,轻度单一胁迫下各项指标在复水后均有所恢复,但胁迫程度过大以及复合胁迫下补偿效应不明显。单一胁迫与复合胁迫之间存在差异,高温干旱复合胁迫对刺槐幼苗水分运输影响较大,且复水之后补偿效应不明显。

Worldwide monitoring shows that the ongoing global warming process has enhanced the extent and increased the frequency of drought events in some subtropical regions.The co-occurrence of elevated temperature and drought can generate great effects on the growth and distribution of plants.In this study,we investigated the effects of combined stress of elevated temperature and drought on water transportation of Robinia pseudoqcacia Linn.seedlings in a controlled greenhouse experiment.The results showed that the specific conductivity(Ks)and hydraulic conductivity(Kh)of seedlings decreased with the increase of stress level.The minimum levels of Ks(3.6%of the controlled level)and Kh(5.3%of the controlled level)appeared in the treatment of 40℃with 40%of field capacity.The stomatal conductance and transpiration rate reached their maximal levels in the treatment of 33℃with 70%of field capacity,and then decreased in the treatment of 40℃with 40%of field capacity.However,in the latter situation,the values were still higher than those in the controlled treatment.The compensation effect of rewatering also decreased with the increasing of stress level;and all related indicators showed signs of recovery only in the treatments of single stress at low levels,but not in the treatments of single stress at high levels or in the treatments of combined stress.These results suggest that compared to the single stress of elevated temperature or drought,their combined stress has greater negative impacts on the water transportation of Robinia seedlings,and also can inhibit the compensation effects of rewatering.