Soil salinization is a global constraint that significantly hampers agricultural production, with cotton being an important cash crop that is not immune to its detrimental effects. The rhizosphere microbiome plays a critical role in plant health and growth, which assists plants in resisting adverse abiotic stresses including soil salinization. This study explores the impact of soil salinization on cotton, including its effects on growth, yield, soil physical and chemical properties, as well as soil bacterial community structures. The results of β-diversity analysis showed that there were significant differences in bacterial communities in saline-alkali soil at different growth stages of cotton. Besides, the more severity of soil salinization, the more abundance ofProteobacteria,Bacteroidotaenriched in rhizosphere bacterial composition where the abundance ofAcidobacteriotaexhibited the opposite trend. And the co-occurrence network analysis showed that soil salinization affected the complexity of soil bacterial co-occurrence network. These findings provide valuable insights into the mechanisms by which soil salinization affects soil microorganisms in cotton rhizosphere soil and offer guidance for improving soil salinization using beneficial microorganisms.

Introduction: Soil moisture, temperature, and salinity critically constrain cotton production in saline soils. Understanding how cotton photosynthetic characteristics and yield respond to seasonal water-heat-salt dynamics is essential for improving management practices in these challenging environments.Methods: A two-year field study (2015–2016) was conducted comparing cotton growth, photosynthetic characteristics, and yield in mildly, moderately, and severely salinized fields. Seasonal soil water-salt dynamics in the 0–200 cm layer were monitored.Results: seasonal rainfall and temperature fluctuations significantly influenced soil water-salt dynamics in the 0-140 cm layer. During spring (April-May), drought maintained soil salinity above 3 g/kg, while low temperatures delayed cotton germination by over a day. In rainy season (July-August), rainfall leached salts from topsoil (0-40 cm), reducing salinity to below 5 g/kg and alleviating salt stress. Mildly saline fields exhibited superior photosynthetic performance, with leaf area index, chlorophyll content, and canopy photosynthetic rate being 1.2–1.5 times higher than in moderate/severe fields. These fields also showed extended "source-sink" organ development periods (16–28 days for "source," 4–24 days for "sink") and 13.8%–18.8% greater boll weight, ultimately achieving a seed cotton yield of 3,303 kg/ha—34.3%–120.7% higher than yields from moderate/severe fields.Discussion: Our results indicate that excessive soil salinity primarily impairs photosynthetic capacity and disrupts photosynthate allocation to bolls. Strategic interventions like drip irrigation could mitigate salt stress while improving photosynthetic efficiency and yield, providing practical solutions for cotton cultivation in saline fields.

Restructuring tilth layers (RTL) is a tillage method that exchanges the 0–20 and 20–40 cm soil layers that can be applied during cotton cultivation to increase cotton yield, eliminate weeds and alleviate severe disease, including Verticillium wilt. However, the mechanism by which RTL inhibits Verticillium wilt is unclear. Therefore, we investigated the distribution of microbial communities after rotary tillage (CK) and RTL treatments to identify the reasons for the reduction of Verticillium wilt in cotton fields subjected to RTL. Illumina high-throughput sequencing was used to sequence the bacterial and fungal genes. The disease incidence and severity of Verticillium wilt decreased by 28.57% and 42.64%, respectively, after RTL. Moreover, RTL significantly enhanced bacterial richness and evenness at 20–40 cm and -reduced the differences in fungal evenness and richness between soil depths of 0–20 and 20–40 cm. The number of Verticillium dahliae decreased, while the relative abundance of biocontrol bacteria such as Bacillus and Pseudoxanthomonas increased significantly following RTL. Overall RTL improved bacterial diversity, decreased the number of Verticillium dahliae and increased the relative abundance of biocontrol bacteria, which may have suppressed the occurrence of Verticillium wilt in cotton fields.

Background Restructuring tilth layers (RTL) is a tillage method that exchanges the 0–20 cm and 20–40 cm soil layers that can be applied during cotton cultivation to inhibit Verticillium wilt. This inhibitory effect may be related to changes in the soil microbial community after RTL. Therefore, we investigated the distribution of microbial communities after rotary tillage (CK) and RTL treatments to identify the reasons for reduction of Verticillium wilt in cotton fields subjected to RTL. Results Illumina high-throughput sequencing was used to sequence the bacterial 16S rRNA (V3–V4) and fungal internal transcribed spacer (ITS2) genes at soil depths of 0–20 and 20–40 cm. The incidence rate and incidence index of Verticillium wilt decreased by 28.57% and 42.64%, respectively, after RTL practice relative to CK. Moreover, RTL significantly enhanced the richness and evenness of bacteria at 20–40 cm and narrowed the difference in fungal evenness and richness between soil depths of 0–20 and 20–40 cm. The number of Verticillium dahlia decreased, while the relative abundance of biocontrol bacteria such as Bacillus and Pseudoxanthomonas increased significantly. Conclusion RTL improved bacterial diversity, decreased the number of Verticillium dahliae and increased the relative abundance of biocontrol bacteria, which may have suppressed the occurrence of Verticillium wilt in cotton fields.

Background In order to study the effects of spatial distribution and yearly migration variations of soil water and salt in coastal saline land on photosynthetic production and yield formation of cotton, spatial distribution characteristics of water content, salinity, and pH in soil at 0–200 cm depths in 3 cotton fields that were similar in locality but differed markedly in degree of salinization were determined in April through October, and photosynthetic characteristics and photosynthate accumulation of cotton were also determined. Results The study shows that, the slightly salinized cotton field had lower soil salinity and pH, where soil water content was lower in rainy season (July–August), and at the late reproductive stage (September–October), soil water content was markedly higher than that in the moderately salinized cotton field, where cotton suffered smaller salt-alkali stress, photosynthetic production matched well with hydrothermal resource, the sink organ had a long photosynthate accumulation time and was at the active material accumulation stage for a long time; salt-alkali stress to the moderately salinized cotton field was relieved in rainy season, but at the early reproductive stage (April–June) and the late reproductive stage of cotton, salt-alkali stress remained evident, and photosynthetic production fit more poorly with the rich photothermal resource stage; the severely salinized cotton field subjected to prolonged high salt-alkali stress resulted in low levels of photosynthetic production capacity and yield. Conclusions For the severely salinized cotton field, salt inhibition and other relevant agronomic actions should be taken with greater efforts; for the moderately salinized cotton field, water and fertilizer management should be tightened at the early reproductive stage of cotton; for the slightly salinized cotton field, high-quality efficient cotton production should be developed.