Field experiments were conducted in 2017 and 2018, in order to investigate the effects of potassium (K) application on photosynthetic capacity and carbohydrate metabolism of the leaf subtending the cotton boll (LSCB) under salt stress. Three salinity treatments (EC = 1.68∼1.78, 6.21∼6.42 and 10.59∼11.08 dS m⁻¹) with three K levels (0, 150, 300 kg K₂O ha^-1) applied in each salinity treatment, were imposed on two cotton (Gossypium hirsutum L.) cultivars differing in salt sensitivity (CCRI-79, salt tolerant and Simian 3, salt sensitive). The results indicated that under salt stress: (1) K application increased LSCB K⁺/Na⁺ ratio since Na⁺ concentration decreased and K⁺ concentration increased. Cotton boll (capsule wall, seed and lint) biomass, total boll number, boll weight and seed cotton yield were also increased; (2) K application improved net photosynthetic rates (Pn) of LSCB by increasing stomatal conductance rates (Gs), chlorophyll a and b concentrations and chlorophyll a/b ratio; (3) K application decreased soluble sugar, sucrose and starch concentrations of LSCB through increases in sucrose phosphate synthase (SPS) and sucrose synthase (SuSy) activities and decreases in sucrose acid invertase (SAI) activity. The results of this study indicated that K fertilizer application rates have a regulating effect on LSCB’s photosynthetic properties and carbohydrate metabolism under salt stress, thus providing a theoretical foundation for increasing cotton yield under salt stress.

2017年和2018年进行了田间试验，研究了钾（K）施用对盐胁迫下棉铃（LSCB）叶片光合能力和碳水化合物代谢的影响。三种盐度处理（EC = 1.68∼1.78、6.21∼6.42 和 10.59∼11.08 dS m ^-1），在每个盐度处理中应用三个 K 水平（0、150、300 kg K ₂ O ha ^-1），对两个棉花 ( Gossypium hirsutum L.) 品种的盐敏感性不同（CCRI-79，耐盐和 Simian 3，盐敏感）。结果表明，盐胁迫下：（1）施钾增加了LSCB K ⁺ /Na ⁺比值，因为Na ⁺浓度降低，K ⁺浓度增加。棉铃（荚膜壁、种子和皮棉）生物量、总铃数、铃重和籽棉产量也有所增加；(2) 施钾通过提高气孔导度 ( Gs )、叶绿素a和b浓度以及叶绿素a / b来提高 LSCB 的净光合速率 ( Pn )比率; (3) 施钾通过增加蔗糖磷酸合酶 (SPS) 和蔗糖合酶 (SuSy) 活性以及降低蔗糖酸转化酶 (SAI) 活性来降低 LSCB 的可溶性糖、蔗糖和淀粉浓度。本研究结果表明，钾肥施用量对盐胁迫下LSCB的光合特性和碳水化合物代谢具有调节作用，为提高盐胁迫下棉花产量提供了理论基础。