A pot experiment with two potassium (K) levels 0.15 (+K) and 0 (−K) g K₂O kg⁻¹ soil and two irrigation regimes well-watered (W_w) and water-deficit (W_d) imposed on two rice genotypes drought-sensitive (CR) and drought-resistant (WDR) was conducted to explore the effects of K deficiency on water use efficiency, leaf water status, osmotic adjustment, gas exchange traits and stomatal characteristics of rice under water deficit. The results showed that K deficiency broke water balance of plants under deficit irrigation by reducing relative water content and water potential of leaf, thereby limited water deficit tolerance of both rice genotypes. In addition, K deficiency resulted in a reduction in stomatal area and conductance, which aggravated the negative impact of water deficit on leaf gas exchange, thereby reduced grain yield and water use efficiency of rice. It should be noted that sufficient K is an important prerequisite for WDR to show water deficit tolerance. The decrease of leaf water potential and stomatal area was the main reason for the limited water deficit tolerance of WDR caused by K deficiency. Our results indicated that K plays an important role in maintaining water deficit tolerance of rice, which provides scientific basis for the breeding of drought-resistant genotypes and management of water and K in paddy fields.

对两种钾 (K) 水平 0.15 (+K) 和 0 (-K) g K ₂ O kg ^-1土壤和两种灌溉方式充分浇水 (W _w ) 和缺水 (W _d ) 进行盆栽试验以干旱敏感（CR）和抗旱（WDR）2个水稻基因型为研究对象，探讨缺钾对缺水条件下水稻水分利用效率、叶片水分状况、渗透调节、气体交换性状和气孔特征的影响。结果表明，缺钾破坏了植物水分平衡通过降低叶片的相对含水量和水势来进行亏缺灌溉，从而限制两种水稻基因型的缺水耐受性。此外，缺钾导致气孔面积和导度降低，加剧了水分亏缺对叶片气体交换的负面影响，从而降低了水稻的产量和水分利用效率。需要注意的是，充足的钾是 WDR 表现出耐缺水能力的重要前提。叶水势降低气孔面积是缺钾引起的WDR耐缺水能力受限的主要原因。我们的研究结果表明，K在维持水稻耐缺水性中起重要作用，为水稻抗旱基因型选育和水钾管理提供科学依据。