Salinity stress significantly hampers cotton seed germination and seedling growth. Employing plant growth regulators stands out as an effective strategy to mitigate salt stress. In this study, we assessed the impact of varying concentrations of natural composite salt conditions (0%, 0.6%, and 1.2%) on cotton seed germination, seedling growth, and physiology. Additionally, we explored the effects of compound sodium nitrophenolate (CSN: 2 mg·L⁻¹ and 10 mg·L⁻¹), 24-epibrassinolide (EBR: 0.02 mg·L⁻¹ and 0.1 mg·L⁻¹), and gibberellic acid (GA: 60 mg·L⁻¹ and 300 mg·L⁻¹), against a control (CK: distilled water) group. The results indicate that with an increase in the composite salt concentration, the germination potential (GP) and germination rate (GR) of cotton seeds gradually decrease. Simultaneously, the fresh weight and root vitality of seedlings also correspondingly decrease, while the degree of membrane lipid peroxidation increases. Under high-salt (1.2%) conditions, soaking treatments with CSN and EBR significantly enhance both GP (45–59% and 55–64%) and GR (30–33% and 39–36%) compared to the CK. However, the GA treatment does not increase the GP and GR of cotton. Moreover, under high-salt (1.2%) conditions, CSN and EBR treatments result in the increased activities of superoxide dismutase (56–66% and 71–80%), peroxidase (20–24% and 37–51%), and catalase (26–32% and 35–46%). Consequently, cotton exhibits a relatively good tolerance to natural composite salts. Soaking treatments with CSN and EBR effectively improve cotton germination by enhancing antioxidant enzyme activities, thereby strengthening cotton’s tolerance to salt stress. These findings offer new insights for enhancing the salt tolerance of cotton.

Excessive salt content in soil has adverse effects on cotton production, especially during the germination and seedling stages. γ-aminobutyric acid (GABA) is an important active substance that is expected to improve the resistance of plants to abiotic stresses. This study focused on two cotton cultivars (Gossypium hirsutum L.: Tahe 2 and Xinluzhong 62) and investigated the impact of exogenous GABA (0, 1, 2, 3, and 4 mM) on seed germination, seedling growth, and related morphological, physiological, and biochemical indicators under salt stress (150 mM NaCl). The results showed that salt stress significantly reduced the germination rate and germination index of cotton seeds (decreased by 20.34% and 32.14% for Tahe 2 and Xinluzhong 62, respectively), leading to decreased seedling height and biomass and causing leaf yellowing. Salt stress induced osmotic stress in seedlings, resulting in ion imbalance (marked reduction in K⁺/Na⁺ ratio) and oxidative damage. Under salt stress conditions, exogenous GABA increased the germination rate (increased by 10.64~23.40% and 2.63~31.58% for Tahe 2 and Xinluzhong 62, respectively) and germination index of cotton seeds, as well as plant height and biomass. GABA treatment improved leaf yellowing. Exogenous GABA treatment increased the content of proline and soluble sugars, with varying effects on betaine. Exogenous GABA treatment reduced the Na⁺ content in seedlings, increased the K⁺ content, and increased the K⁺/Na⁺ ratio (increased by 20.44~28.08% and 29.54~76.33% for Tahe 2 and Xinluzhong 62, respectively). Exogenous GABA treatment enhanced the activities of superoxide dismutase and peroxidase, and reduced the accumulation of hydrogen peroxide and malondialdehyde, but had a negative impact on catalase activity. In conclusion, exogenous GABA effectively improved cotton seed germination. By regulating osmoprotectant levels, maintaining ion homeostasis, and alleviating oxidative stress, GABA mitigated the adverse effects of salt stress on cotton seedling growth.

Soil salinization is a major limiting factor for cotton growth in Southern Xinjiang. Studying technologies and mechanisms to improve cotton salt tolerance is of significant importance for the development and utilization of saline–alkaline land. In this study, ‘Xinluzhong 40’ cotton was used as the material, and 150 mmol·L⁻¹ sodium chloride (NaCl) and 1.2% natural saline–alkaline soil extract were employed to simulate single-salt (SS) and mixed-salt (MS) stresses, respectively. The effects of different exogenous substances (sodium nitrophenolate, 24-epibrassinolide, and γ-aminobutyric acid) on the growth characteristics of cotton under salt stress were investigated. The results show that: (1) Under salt stress, the height and biomass of cotton (50 d old) were reduced. Both SS and MS stresses led to increased superoxide dismutase (SOD) activity, elevated proline (PRO) content (with an increase of 50.01% and no significant difference), and increased malondialdehyde (MDA) content (with increases of 63.14% and 32.42%, respectively). At the same time, catalase (CAT) activity decreased, Na⁺ and Cl⁻ contents increased, K⁺ content decreased, and the K⁺/Na⁺ ratio was reduced. (2) Application of sodium nitrophenolate (S), 24-epibrassinolide (E), and γ-aminobutyric acid (G) significantly improved SOD activity and PRO content while reducing MDA content (decreased by 29.33%, 25.48%, and 30.47% compared to SS treatment; and 1.68%, 5.21%, and 5.49% compared to MS treatment, respectively). They also increased CAT activity (increased by 75.97%, 103.24%, and 80.79% compared to SS treatment; and 91.06%, 82.43%, and 119.68% compared to MS treatment, respectively) and K⁺/Na⁺ ratio (increased by 57.59%, 66.35%, and 70.50% compared to SS treatment; and 38.31%, 42.97%, and 66.66% compared to MS treatment, respectively), reduced Cl⁻ content, and promoted increases in plant height and biomass. The effects of exogenous substances on antioxidant capacity and ion balance under salt stress were significant, particularly under SS stress. (3) Principal component analysis revealed that under SS and MS stresses, principal component 1 mainly reflects cotton’s antioxidant capacity, with SOD, CAT, and PRO having high weights; principal component 2 mainly reflects cotton’s ion balance and nutrient absorption, with root Na⁺, stem Na⁺, leaf Na⁺, root K⁺, and root Cl⁻ having high weights. These findings highlight the potential of exogenous substances to improve cotton salt tolerance and provide scientific evidence for cotton cultivation on saline–alkaline land, offering new insights into cultivation techniques from an applied research perspective.

Nitrogen (N), phosphorus (P), and potassium (K) are important nutrients limiting cotton yield. Although N, P, and K fertilization is an important practice for improving cotton productivity, their fertilizer use efficiencies remain insufficiently evaluated in Xinjiang, China. In this study, field experiments were conducted at 57 sites across the major cotton-growing areas of Xinjiang during 2021–2022. Four fertilization treatments, PK, NK, NP, and NPK, were established to evaluate cotton yield response, nutrient accumulation, and fertilizer use efficiencies of N, P, and K under different soil fertility conditions. The results indicated that the cotton yield in both southern and northern Xinjiang significantly increased under NPK treatment, with mean yields of 6300 and 7361 kg ha⁻¹, respectively. The use efficiencies of N, P, and K were 39.8%, 19.5%, and 51.4% in southern Xinjiang, and 40.3%, 20.2%, and 66.1% in northern Xinjiang, respectively. For every 100 kg of seed cotton produced, nutrient uptake was 4.64 kg N, 1.43 kg P₂O₅, and 3.67 kg K₂O in southern Xinjiang, and 4.74 kg N, 1.48 kg P₂O₅, and 4.58 kg K₂O in northern Xinjiang, indicating relatively high N and K requirements but lower P demand in cotton production. Cotton yield in southern Xinjiang was significantly and positively correlated with soil alkali-hydrolyzable N. In northern Xinjiang, cotton yield was significantly and positively correlated with soil organic matter, alkali-hydrolyzable N, and available K, but negatively correlated with available P. Overall, cotton yield was mainly positively affected by soil organic matter, alkali-hydrolyzable N, and available K, whereas K use efficiency was significantly and negatively correlated with N and K rates. The suitable N, P, and K rates for cotton were 285, 120, and 106 kg ha⁻¹ in southern Xinjiang, and 243, 101, and 91 kg ha⁻¹ in northern Xinjiang, respectively. Based on soil fertility classification of cotton fields, the recommended N, P, and K rates were 256–313, 96–117, and 125–153 kg ha⁻¹ in southern Xinjiang, and 219–267, 97–119, and 136–166 kg ha⁻¹ in northern Xinjiang, respectively. Accordingly, reducing N and P inputs in southern Xinjiang, maintaining N and P at appropriate levels in northern Xinjiang, and moderately increasing K are recommended to achieve coordinated improvements in yield stability and N, P, and K use efficiencies.

Soil salinization is a primary environmental factor leading to reduced crop yields, and oil shale waste residues may have the potential to alleviate plant salt stress. This study aims to investigate the effects of three types of oil shale waste residues (fine concentrate ore, fine ore, and semi-coke) on the growth and physiological characteristics of maize seedlings in saline–alkali soil. The results indicate the following: (1) All three types of oil shale waste residues increased the root vitality of seedlings and reduced the root proline content. (2) The three types of oil shale waste residues increased the activity of superoxide dismutase (1.70% to 97.19%) and peroxidase (29.39% to 61.21%) in maize seedlings, but there were differences in their effects on catalase activity. The fine ore and semi-coke treatments increased catalase activity (4.98% to 77.42%), while fine concentrate ore decreased catalase activity (39.28% to 5.30%). (3) The three types of oil shale waste residues effectively alleviated the degree of membrane lipid peroxidation in maize seedling leaves. (4) Principal component analysis showed that the semi-coke treatment was beneficial to the growth and physiology of maize seedlings in saline–alkali soil, with the optimal effect occurring at a 0.2% addition rate. In conclusion, adding semi-coke to saline–alkali soil promotes the growth of maize by regulating its physiological and biochemical mechanisms, alleviating the salt stress on maize seedlings caused by salt content.

Salt stress severely restricts plant growth and reduces crop yield. Strigolactones (SLs) are carotenoid-derived phytohormones involved in the regulation of plant salt tolerance. Salt stress can modulate the expression of SL biosynthetic and signaling genes, thereby affecting SL accumulation and signaling responses. SLs also interact with abscisic acid (ABA), reactive oxygen species (ROS), and other signaling molecules to coordinate downstream stress responses. At the physiological level, SLs alleviate salt stress by maintaining Na⁺/K⁺ homeostasis, enhancing osmotic adjustment and antioxidant defense, and reducing damage to the photosynthetic system. In addition, SLs can enhance plant resource acquisition and adaptive capacity under salt stress by regulating root architecture and promoting hyphal branching of arbuscular mycorrhizal fungi (AMF). This review focuses on SL-mediated regulation of plant salt tolerance at the molecular and physiological levels and further summarizes exogenous SL application strategies for alleviating salt stress, as well as research progress on key genes in the SL pathway for the genetic improvement of salt tolerance. Clarifying the potential of SLs in regulating plant responses to salt stress could provide new insights into sustainable crop production in saline-alkali environments.