Department of Horticulture, University of Georgia, 1111 Miller Plant Science Building, Athens, GA 30602, USA.
Physiol Plant. 2011 Oct;143(2):166-77. doi: 10.1111/j.1399-3054.2011.01493.x. Epub 2011 Jun 28.
Our understanding of plant responses to drought has improved over the decades. However, the importance of the rate of drought imposition on the response is still poorly understood. To test the importance of the rate at which drought stress develops, whole-plant photosynthesis (P(net) ), respiration (R(dark) ), daily carbon gain (DCG), daily evapotranspiration (DET) and water use efficiency (WUE) of vinca (Catharanthus roseus), subjected to different drought imposition rates, were investigated. We controlled the rate at which the substrate dried out with an automated irrigation system that allowed pot weight to decrease gradually throughout the drying period. Fast, intermediate and slow drying treatments reached their final pot weight [500 g, substrate water content (θ) ≈ 0.10 m³ m(-3) ] after 3.1, 6.6 and 10 days, respectively. Although all drying treatments decreased P(net) and R(dark) , slow drying reduced P(net) and R(dark) less than fast drying. At a θ < 0.10 m³ m(-3) , DCG and DET in the slow drying treatment were reduced by ≈50%, whereas DCG and DET in the fast drying treatment were reduced by 85 and 70% at a θ of 0.16 m(3) m(-3) . Plants exposed to slow drought imposition maintained a high WUE, even at θ < 0.10 m³ m(-3) . Overall, physiological responses to low θ were less severe in plants subjected to slow drying as compared with fast drying, even though the final θ was lower for plants exposed to slow drying. This suggests that the rate at which drought stress develops has important implications for the level of acclimation that occurs.
几十年来，我们对植物响应干旱的理解有所提高。然而，干旱施加速度对响应的重要性仍未得到充分理解。为了测试干旱胁迫发展速度的重要性，我们研究了不同干旱施加速度下长春花（Catharanthus roseus）的整株光合作用（P(net)）、呼吸作用（R(dark)）、日碳增益（DCG）、日蒸腾耗水（DET）和水分利用效率（WUE）。我们使用自动化灌溉系统来控制基质变干的速度，使盆重在整个变干过程中逐渐下降。快速、中速和慢速干燥处理分别在 3.1、6.6 和 10 天后达到最终盆重[500g，基质含水量（θ）≈0.10m³m(-3)]。虽然所有干燥处理都降低了 P(net)和 R(dark)，但慢速干燥降低的幅度小于快速干燥。在θ<0.10m³m(-3)时，慢速干燥处理中的 DCG 和 DET 减少了约 50%，而在θ为 0.16m³m(-3)时，快速干燥处理中的 DCG 和 DET 减少了 85%和 70%。暴露于缓慢干旱施加下的植物保持高 WUE，即使在θ<0.10m³m(-3)时也是如此。总的来说，与快速干燥相比，在θ<0.10m³m(-3)时，缓慢干燥处理下的植物对低θ的生理响应不太严重，尽管暴露于缓慢干燥下的植物的最终θ更低。这表明干旱胁迫发展速度对发生的适应水平具有重要意义。
