High temperatures and water-deficit stress limit cotton production around the world. Their individual effects on plant physiology and metabolism have been extensively studied, however, their combination has received considerably less attention. To that end, growth chamber experiments were conducted using cotton (Gossypium hirsutum L.) cultivar ST5288B2F and the objectives were to discern physiological and metabolic alterations after heat and water stress application (single or combined) and recovery, during cotton's vegetative stage. Under water stress conditions, leaf physiological parameters were suppressed and changes in carbohydrate levels, due to alterations in sucrose-metabolizing enzymes activities, were observed. Heat stress alone increased carbohydrate content, and activities of sucrose-degrading enzymes, while leaf physiology remained unaffected. The combined stress did exacerbate decreases in leaf water potential and soluble acid invertase activity, but the rest of the responses were similar to those of water stress. After stress alleviation, leaf physiological parameters of water-stressed plants did not manage to recover and substantial decreases were observed in leaf starch levels and activities of sucrose-cleaving enzymes, while the majority of parameters of heat-shocked plants returned to control levels. Recovery of the plants subjected to the combined stress was comparable to that of water-stressed plants, but significant differences were observed in carbohydrate levels and sucrose synthase activity. Our study demonstrated that under combined stress and post-stress conditions, water stress was the dominant factor affecting cotton leaf physiology and sucrose metabolism, highlighting however, the unique responses of some traits that could not be deduced from the additive effects of the single stresses.

中文翻译：

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热量和水分胁迫及恢复对棉花（Gossypium hirsutum L.）叶片生理和蔗糖代谢的单一和综合影响。

高温和缺水胁迫限制了世界各地的棉花生产。它们对植物生理和代谢的个体影响已得到广泛研究，但是，它们的组合受到的关注却很少。为此，使用棉花（Gossypium hirsutum L.）品种ST5288B2F进行了生长室实验，目的是识别棉花营养期热和水分胁迫（单次或联合施用）和恢复后的生理和代谢变化。在水分胁迫条件下，由于蔗糖代谢酶活性的改变，叶片的生理参数受到抑制，碳水化合物水平发生变化。单独的热应激会增加碳水化合物含量，并增加蔗糖降解酶的活性，而叶片生理却不受影响。组合胁迫确实加剧了叶片水势和可溶性酸转化酶活性的下降，但其余响应与水分胁迫相似。缓解胁迫后，水分胁迫植物的叶片生理参数无法恢复，并且观察到叶片淀粉水平和蔗糖裂解酶活性显着降低，而热休克植物的大多数参数恢复到对照水平。经受联合胁迫的植物的恢复与水分胁迫的植物的恢复相当，但是在碳水化合物水平和蔗糖合酶活性方面观察到显着差异。我们的研究表明，在压力和后压力共同作用下，