盐害是影响农作物产量的主要因素之一，随着人类过度灌溉和工业污染等不合理的开发方式，使得土壤盐碱化程度越来越严重。棉花是一种耐盐作物，被认为是改良盐碱旱地的先锋作物。然而，棉花的耐盐性也是有限的，盐胁迫常抑制种子萌发、出苗，甚至导致死苗，盐碱地成苗难长期困扰棉花生产。近年来一些研究发现，通过生长调节剂缩节胺(DPC)浸种能提高植物的耐盐性，然而DPC调节其耐盐性的内在机理尚不清楚；为探究DPC浸种对盐胁迫下植物种子耐盐性的调节作用，拟选用四个耐盐性差异的棉花材料，从“种子萌发差异 — 渗透平衡态重建 — 离子平衡态重建”的思路进行剖析，阐述不同基因型种子萌发阶段的耐盐性差异，同时揭示DPC浸种调节“渗透和离子平衡态重建”耐盐策略的生理及分子机理。研究成果不仅明确棉花种子萌发阶段的耐盐机理，还可以为棉花耐盐性育种提供理论指导，具有较强的理论价值和实践指导意义。

Salinity is one of the major environmental factors that severely limits productivity and yield in many areas worldwide. Moreover, soil salinization is still expanding and becoming more serious in the world, mainly due to excessive irrigation and industrial pollution, posing a great threat to agricultural sustainability. Although cotton is classified as a salt tolerant crop, its growth is severely reduced at high salinity levels, especially at the germination stage. Salt stress can inhibit the metabolism of dividing and expanding cells, retarding germination and even leading to seed death. Germination is an important and vulnerable stage in the life cycle of plants in saline environments and determines seedling establishment and plant growth. Mepiquat chloride (DPC), a plant growth regulator, has been used worldwide to suppress excessive growth in cotton plants. In recent years, although previous studies have found that DPC can promote salinity tolerance of plants under salt stress, the mechanisms involved in underlying the specific components of protective mechanisms remain poorly understood. To better understand the role of DPC on germination stage, we conducted an experiment to investigate the effect of soaking seed with 200 mg L-1 DPC on germination stage by using four cotton cultivars (differing in salt sensitivities). Seed germination in, and recovery germination from, salt stress were recorded. The effects of salt stress on osmotic effect such as seed water uptake, osmotic adjustment substance and osmotic potential were measured. In addition, ionic effect such as absorption and distribution of Na+ and K+, expression level of ions transporter and H+-ATPase activity were also investigated. In the view of osmotic and ionic adjustment, we aim to investigate the mechanistic explanation for differential salinity tolerance among these cultivars and shed light on the effect of DPC soaking seed on the different coping strategies of salinity tolerance. This research will not only enrich knowledge of salinity tolerance of cotton germination stage in response to salt stress but also provide a framework to identify breeding targets for improving salt resistance in cultivated cotton.