The objective of this study was to investigate the growth and physiological responses cotton plants to salt stress. At seven leaf stage, cotton plants were subjected to two treatments; 0 mM NaCl as the control and 150 mM NaCl as the salt stress treatment, respectively. The effect of salt stress on leaf gas exchange rates, leaf nitrogen concentration, chlorophyll content, leaf K⁺ and Na⁺ concentrations, plant water status, endogenous phytohormone concentrations, dry matter accumulation and partitioning in plant organs was evaluated. The results showed that salt stress significantly decreased plant growth, water consumption, leaf water relations characteristics and leaf gas exchange rates as compared to the control. Under salt, photosynthetic rate was reduced to less extend than did stomatal conductance (g_s) and transpiration rate, resulting in greater intrinsic and instantaneous water use efficiencies compared to the control plants. g_s decreased linearly with decreasing leaf water potential and leaf hydraulic conductance under salt. Salt-stressed plants possessed a significant higher concentration of abscisic acid ([ABA]_leaf), while a significantly lower concentrations of gibberellic acid ([GA3]_leaf) and zeatin riboside ([ZR]_leaf) in leaf than those grown under control. Negative linear relationships were found between g_s and [ABA]_leaf, ratio of [ABA]_leaf to [GA3]_leaf, ratio of [ABA]_leaf to ([GA3]_leaf+[ZR]_leaf), respectively. Salt stress significantly decreased leaf K⁺ concentration, the ratio of K⁺/Na⁺ in leaf, shoot growth and biomass partitioning into leaf and stem, whereas increased leaf chlorophyll content, leaf nitrogen concentration and biomass partitioning into boll. Although the water use efficiency of plant biomass was unaffected, the water use efficiency of boll biomass was significantly enhanced by salt stress. Collectively, salt-induced changes in both hydraulic and chemical properties were involved in mediating the leaf gas exchange response to salt stress, and the enhanced leaf nitrogen concentration and biomass partitioning into boll may lead to a sustained yield with less water consumption in cotton plants grown under moderate salinity stress.

中文翻译：

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棉花对盐胁迫的生长和生理响应

这项研究的目的是调查棉花植物对盐胁迫的生长和生理响应。在七叶期，对棉花植株进行了两次处理。分别以0 mM NaCl作为对照和150 mM NaCl作为盐胁迫处理。盐胁迫对叶片气体交换速率，叶片氮浓度，叶绿素含量，叶片K ⁺和Na ^+的影响浓度，植物水分状况，内源性植物激素浓度，干物质积累和植物器官中的分配进行了评估。结果表明，与对照相比，盐胁迫显着降低了植物的生长，耗水量，叶片水分关系特征和叶片气体交换率。在盐条件下，光合速率的降低幅度小于气孔导度（g _s）和蒸腾速率，因此与对照植物相比，其固有和瞬时的水分利用效率更高。g _s在盐胁迫下随叶片水势和叶片水力传导率_的降低而线性下降。盐胁迫的植物中脱落酸（[ABA]_叶的浓度显着较高），而_叶中的赤霉素（[GA3]_叶）和玉米素核糖苷（[ZR]_叶）的浓度明显低于对照。g _s与[ABA]_叶，[ABA]_叶与[GA3]_叶的比例，[ABA]_叶与（[GA3]_叶+ [ZR]_叶）的比例分别为负线性关系。盐胁迫显着降低了叶片K ⁺浓度，K ⁺ / Na ⁺之比在叶片中，枝条生长和生物量分配到叶片和茎中，而增加的叶绿素含量，叶片氮浓度和生物量分配到铃中。尽管植物生物量的水分利用效率没有受到影响，但盐胁迫显着提高了棉铃生物量的水分利用效率。集体地，盐诱导的水硬性和化学性质的变化都参与了调解盐胁迫下的叶片气体交换反应，并且增强的叶片氮浓度和生物量分配到铃中可能导致棉花产量持续降低而耗水量减少在中等盐度压力下。