Hawkesbury Institute for the Environment, Hawkesbury Campus, University of Western Sydney, Locked Bag 1797, Penrith, New South Wales, 2751, Australia.
Plant Cell Environ. 2014 Jul;37(7):1598-613. doi: 10.1111/pce.12260. Epub 2014 Feb 13.
It has been reported that elevated temperature accelerates the time-to-mortality in plants exposed to prolonged drought, while elevated [CO(2)] acts as a mitigating factor because it can reduce stomatal conductance and thereby reduce water loss. We examined the interactive effects of elevated [CO(2)] and temperature on the inter-dependent carbon and hydraulic characteristics associated with drought-induced mortality in Eucalyptus radiata seedlings grown in two [CO(2)] (400 and 640 μL L(-1)) and two temperature (ambient and ambient +4 °C) treatments. Seedlings were exposed to two controlled drying and rewatering cycles, and then water was withheld until plants died. The extent of xylem cavitation was assessed as loss of stem hydraulic conductivity. Elevated temperature triggered more rapid mortality than ambient temperature through hydraulic failure, and was associated with larger water use, increased drought sensitivities of gas exchange traits and earlier occurrence of xylem cavitation. Elevated [CO(2)] had a negligible effect on seedling response to drought, and did not ameliorate the negative effects of elevated temperature on drought. Our findings suggest that elevated temperature and consequent higher vapour pressure deficit, but not elevated [CO(2)], may be the primary contributors to drought-induced seedling mortality under future climates.
据报道，在长时间干旱条件下，高温会加速植物的死亡时间，而升高的[CO(2)]则可以作为一种缓解因素，因为它可以降低气孔导度，从而减少水分流失。我们研究了升高的[CO(2)]和温度对桉树幼苗相互依赖的碳和水力特征的交互作用，这些特征与在两种[CO(2)]（400 和 640 μL/L）和两种温度（环境和环境+4°C）处理下生长的干旱诱导性死亡有关。幼苗经历了两个受控的干燥和再水合循环，然后停止供水，直到植物死亡。木质部空化的程度被评估为茎水力传导率的损失。与环境温度相比，高温通过水力衰竭导致更快的死亡率，并且与更大的耗水量、增加的气体交换特征对干旱的敏感性以及木质部空化的更早发生有关。升高的[CO(2)]对幼苗对干旱的响应几乎没有影响，也没有减轻高温对干旱的负面影响。我们的研究结果表明，在未来气候条件下，升高的温度和随之而来的更高的蒸气压亏缺，而不是升高的[CO(2)]，可能是导致干旱诱导幼苗死亡的主要因素。
