The individual effect of high temperatures or water-deficit stress on cotton has been studied extensively; however, their combined effects were less studied. To that end, an experiment was imposed with a heat-sensitive (Sumian 15) and a heat-tolerant (PHY370WR) cultivar in 2016–2018 and two temperature regimes including ambient temperature (AT, 31.0/26.4°C) and elevated temperature (ET, 33.4/28.9°C), and three soil relative water content (SRWC) levels including (75 ± 5)%, (60 ± 5)% and (45 ± 5)% were performed. Results showed that the decline in boll number was the primary driver of yield loss, while the decreases in boll weight minimally impacted yield under drought and combined treatments. Besides, elevated temperature and drought stress performed significant interactions on boll weight (except in 2018) and seed cotton yield (except for Sumian 15 in 2017). Specifically, seed cotton yield was reduced by 23%–35% in Sumian 15 and by 8%–13% in PHY370WR under ET₆₀ (ET with SRWC (60 ± 5)%), while the reduction was 44%–54% in Sumian 15 and 37%–43% in PHY370WR under ET₄₅ (ET with SRWC (45 ± 5)%), which produced lower yields than any other treatment combination or any single abiotic stress factor. Furthermore, significant interactions between the two stresses were observed in fibre length of Sumian 15 and strength (except for PHY370WR in 2018) and micronaire (except for Sumian 15 in 2017 and for PHY370WR in 2018) of both cultivars. Elevated temperature exacerbated the negative impacts of drought on fibre length but offset them on fibre strength and micronaire. Finally, the economic benefit among different treatments was evaluated. Compared to the control, ET₄₅ suffered the biggest economic loss by 2,536.7 USD ha⁻² in Sumian 15 and by 2,167.8 USD ha⁻² in PHY370WR, respectively. Quantifying the interactive effects of drought and elevated temperature on cotton yield and fibre quality should allow researchers to better understand the economic implications of these two stresses which often occur concurrently under field conditions.

中文翻译：

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量化高温和干旱胁迫对棉花产量和纤维品质的个体和互动影响

高温或缺水胁迫对棉花的个体影响已得到广泛研究；但是，对它们的综合作用的研究较少。为此，在2016–2018年间对热敏（Sumian 15）和耐热（PHY370WR）品种进行了实验，并采用了两种温度模式，包括环境温度（AT，31.0 / 26.4°C）和高温（ ET，33.4 / 28.9°C）和三种土壤相对含水量（SRWC）水平包括（75±5）％，（60±5）％和（45±5）％。结果表明，铃数的减少是产量损失的主要驱动力，而铃重的减少对干旱和综合处理下的单产影响最小。除了，高温和干旱胁迫对棉铃重（2018年除外）和籽棉产量（2017年苏棉15号除外）具有显着的相互作用。具体而言，在ET下，苏棉15号的籽棉产量降低了23％–35％，而PHY370WR的种棉产量降低了8％–13％₆₀（ET SRWC（60±5）％），而在ET ₄₅下，苏美15下降44％–54％，PHY370WR下降37％–43％（SRWC（45±5）％的ET）比任何其他处理组合或任何单一非生物胁迫因素的产量都低。此外，两个品种的苏棉15的纤维长度和强度（2018年的PHY370WR除外）和马克隆值（2017年的Sumian 15和2018年的PHY370WR除外）均观察到两个应力之间存在显着的相互作用。温度升高加剧了干旱对纤维长度的负面影响，但抵消了它们对纤维强度和马克隆值的影响。最后，评估了不同处理方法之间的经济效益。与对照组相比，ET ₄₅遭受的经济损失最大，为2,536.7 USD ha ^-2在Sumian 15分别为PHY370WR和2,167.8 USD ha ^-2。量化干旱和高温对棉花产量和纤维品质的相互作用影响，应该使研究人员更好地了解这两种压力的经济影响，这两种压力通常在田间条件下同时发生。