Cotton is often negatively impacted by drought periods; thus, plant traits that alleviate the impacts of drought on cotton are highly desirable. The limited‐transpiration rate (TR_lim) trait under high vapour pressure deficit (VPD) can conserve soil water and prolong crop physiological activity as water deficit progresses. The current research objective was to compare the expression of TR_lim in cotton cultivars under variable VPD and temperatures by whole‐plant transpiration in controlled environments and by leaf‐level gas exchange measurements in the field. All cultivars expressed the TR_lim trait in a controlled environment with high VPD at 32°C; however, at 38°C, only 5 out of 7 commercial and 2 out of 4 conventional cultivars expressed TR_lim. Field trials during 2017 and 2018 showed all 4 commercial cultivars that expressed TR_lim in a controlled environment at 38°C expressed TR_lim, but shifts in VPD breakpoints were observed. Among conventional cultivars, 2 out of 4 expressed TR_lim trait. Cultivars that expressed TR_lim also delayed wilting under rainfed environments when soil water deficits developed and resulted in greater lint yields. Three commercial and two conventional cultivars that expressed the TR_lim trait in field trials also resulted in greater predawn leaf water potential (LWP). Cultivars that expressed the TR_lim trait had significantly higher lint yields only during 2017. This study indicates that the impact of TR_lim trait on yield is relatively small in years with adequate rainfall.

中文翻译：

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受控和雨养环境下棉花品种气孔导度对高蒸气压亏缺的响应变化

棉花经常受到干旱时期的不利影响；因此，非常需要减轻干旱对棉花影响的植物性状。高水分压亏缺（VPD）下的限制蒸腾速率（TR _lim）性状可以节约土壤水分，并随着水分亏缺的发展延长作物的生理活性。当前的研究目标是通过受控环境中的全植物蒸腾和田间叶水平的气体交换测量，比较可变VPD和温度下棉花中TR _lim的表达。在32°C的VPD高的受控环境中，所有品种都表达了TR _lim特性; 然而，在38°C下，只有7个商业品种中的5个和4个常规品种中的2个表达了TR _lim。2017年和2018年的田间试验表明，所有4个在38°C受控环境中均表达TR _lim的商业品种均表达TR _lim，但观察到VPD断点发生了变化。在常规品种中，每4个品种中就有2个表现出TR _lim特性。表达TR _lim的品种还可以在雨养环境下延缓枯萎，因为土壤缺水会导致皮棉产量增加。在田间试验中表现出TR _lim特性的3个商业品种和2个常规品种也产生了更大的黎明前叶片水势（LWP）。表达TR _lim的品种该性状仅在2017年才有较高的皮棉产量。这项研究表明，在降雨充足的年份中，TR _lim性状对产量的影响相对较小。