[Objective] The study aims at investigating the optimal transformation system to enhance genetic transformation efficiency of cotton shoot tips. [Methods] The shoot tips of Baimian 1 seeds were used as the explant. Different concentrations of ethylenediaminetetra-acetic acid(EDTA), various water bath treatment times, and different concentrations of bacterial suspension were set during the infection stage. During the co-culture stage, six exogenous additives (lanthanum chloride, EDTA, salicylic acid, thidiazuron, zeatin, and silver nitrate) at varying concentrations were introduced. During the screening stage, the concentrations of spectinomycin and ratios of various plant growth regulators (kinetin, naphthalene acetic acid, 6-benzylaminopurine, indole butyric acid, and 2,4-dichlorophenoxyacetic acid) were adjusted. The effects of these treatments on the transient transformation efficiency, germination rate, seedling survival rate, and positive rate of cotton shoot tips were analyzed. [Results] During the infection stage, adjusting the OD₆₀₀ of bacterial suspension to 0.7 and pre-treating shoot tips with 100 μmol·L^-1 EDTA in a water bath for 15 min can significantly improve the transient transformation efficiency (28.09%). During the co-culture phase, adding 1.5 mg·L^-1 thidiazuron obtained the highest transient transformation efficiency (41.47%) and a relatively high germination rate (32.79%). In the screening phase, adding 200 mg·L^-1 spectinomycin resulted in a higher seedling survival rate (32.44%) and the highest positive rate (19.97%); 1 mg·L^-1 6-benzylaminopurine + 0.1 mg·L^-1 naphthalene acetic acid treatment yielded a significantly higher germination rate (34.73%) than other plant growth regulator combinations. Under the optimized conditions described above, the transformation efficiency of cotton shoot tips reached 7.62%, with a positive rate of 18.52%. [Conclusion] The cotton genetic transformation system has been optimized, providing a reference for further improving the transformation efficiency of cotton shoot tips.

[Objective] This study aimed to investigate the role of sucrose in cotton resistance against Verticillium wilt and verify the function of GhSWEET55, providing a theoretical basis for revealing the molecular mechanism of cotton resistance to Verticillium wilt. [Methods] Cotton were inoculated with Verticillium dahliae using the root-wounding method. Sucrose content in cotton roots was determined by spectrophotometry. Differentially expressed genes were obtained by transcriptome sequencing. The enrichment of differentially expressed genes was studied by KEGG pathway analysis. Differentially expressed genes and SWEET family expression patterns were analyzed by transcriptome sequencing, and validated by quantitative real-time polymerase chain reaction (qRT-PCR). Bioinformatics analysis was performed to characterize the protein sequence features and phylogenetic relationships of GhSWEET55, and its expression pattern was analyzed by qRT-PCR. The function of GhSWEET55 was verified by virus-induced gene silencing (VIGS). [Results] Sucrose content in cotton roots increased significantly at 12 h and 48 h after V. dahliae infection, and decreased significantly at 96 h after V. dahliae infection. Some differentially expressed genes were enriched in sucrose-related energy metabolism pathways and defense response pathways. Most members of the SWEET family were differentially expressed, and GhSWEET55 from Clade III was significantly up-regulated. GhSWEET55 was predominantly expressed in cotton leaves, and the encoded protein was localized to the plasma membrane. Silencing of GhSWEET55 enhanced cotton resistance to Verticillium wilt. [Conclusion] Sucrose is involved in cotton resistance against Verticillium wilt. The SWEET gene family responds to V. dahliae infection. GhSWEET55 negatively regulates cotton resistance to V. dahliae.

[Objective] A disease that damages cotton fiber has been found in the Xinjiang cotton fields in recent years. The infected cotton fiber turned into mouse-gray and failed to fluff as the boll opens, losing all commercial value. The purpose of this study was to identify the pathogen causing lint rot in Xinjiang cotton fields, and to explore the relationship between mite and disease transmission. [Methods] A total of 161 diseased boll samples were collected from 25 cotton-growing units across northern and southern Xinjiang in 2021 and 2023. The strains were isolated and purified using the tissue isolation method. The pathogen was identified based on morphological characteristics, molecular biological analysis, and pathogenicity test. Different tissues and organs of cotton plants were artificially inoculated in the field to determine the infection sites of the pathogen. The correlation between cotton boll rot and mite was investigated by examining the occurrence frequency of the mite in diseased bolls in cotton field, and combining with the experiment of artificially inoculating healthy detached cotton bolls with mites carrying conidia. [Results] The cotton Nigrospora lint rot is widespread in Xinjiang cotton fields, and the damage is gradually worsening. A total of 146 Nigrospora strains were isolated from diseased samples collected from cotton fields in Xinjiang. The morphological characteristics of the strains were consistent with N. gorlenkoana. The DNA sequences of the internal transcribed spacer in eukaryotic ribose rDNA-ITS, translation elongation factor TEF1-α, and β-tubulin TUB2 in 27 representative strains exhibited high homology with N. gorlenkoana. Field and laboratory pathogenicity tests of 5 representative strains showed that the lint displayed extensive black-gray rot. Therefore, the pathogen causing cotton Nigrospora lint rot in Xinjiang was identified as N. gorlenkoana. The pathogen exclusively infected cotton fiber and did not affect seed, leaf, stem, bud, and flower of cotton. Siteroptes reniformis was closely associated with cotton Nigrospora lint rot. Adult mites or their physogastric females were found in all the diseased bolls, and they can carry the conidia of N. gorlenkoana into the bolls to spread the disease. [Conclusion] The cotton lint rot caused by N. gorlenkoana in Xinjiang in recent years is a disease specifically targeting cotton fiber, with S. reniformis as the primary transmission vector.

[Objective] The aim of this study was to analyze the genetic diversity of morphological traits, yield, and fiber quality characteristics in introduced upland cotton resources so as to provide references for the exploration and utilization of superior germplasm. [Methods] A total of 213 Gossypium hirsutum accessions introduced from Central Asia were planted in Aksu, Xinjiang, from 2023 to 2024. Twenty-six traits were measured. Through analysis of the coefficient of variation and genetic diversity index, correlation analysis, cluster analysis, principal component analysis, and comprehensive evaluation, superior germplasms were identified and screened. [Results] The genetic diversity indices of 13 traits (plant type, stem color, main stem hardness, stem hair number, leaf color, corolla color, anther color, style length, fruiting branch type, boll arrangement, boll type, ease of boll opening, and color of short fiber) ranged from 0.09 to 1.04. For the other 13 traits (growth period, plant height, first fruiting branches node, number of fruiting branches per plant, number of bolls per plant, boll weight, lint percentage, seed index, upper half mean length, uniformity index, breaking tenacity, breaking elongation, and micronaire), the coefficients of variation ranged from 1.37% to 19.20%, and the genetic diversity indices ranged from 1.85 to 2.11. Among them, the genetic diversity indices of 12 traits were greater than 2. Plant height showed highly significant or significant positive correlations with the number of fruiting branches per plant and lint percentage. Boll weight was significantly positively correlated with seed index, upper half mean length, and uniformity index. Cluster analysis classified the materials into six major groups at a Euclidean distance of 9.5. Groups Ⅱ and Ⅵ exhibited superior overall performance. From these two groups, 31 materials met the Type Ⅲ fiber quality standard, and one material met the Type Ⅱ standard. Group Ⅱ contained the highest number of resources with high boll weight (≥ 7 g). Principal component analysis extracted five principal components, with a cumulative contribution rate of 73.522%. The top ten materials based on comprehensive evaluation scores were 13TJ272 selected line, 13TJ186 selected line, Jimian 5, 13TJ111 selected line, 12TJ11 selected line, 17W1-17, 12TJ15 selected line 1, 13TJ229 selected line, 17W1-3, and 13TJ207. [Conclusion] The 213 introduced upland cotton resources exhibit relatively rich genetic diversity. Ten materials with high comprehensive scores were screened, which can serve as genetic improvement materials for breeding new upland cotton varieties.

[Objective] To address the issues of idle field in winter and spring, low utilization efficiency of cotton straw, and declining profitability in cotton production in the Yellow River Basin, a cotton-Stropharia rugosoannulata double cropping system was proposed, which utilize crushed cotton straw for S. rugosoannulata cultivation in the winter fallow field, followed by S. rugosoannulata residue returning to field. The objective was to investigate the comprehensive effects of this system on productivity, economic benefit, and soil fertility, aiming to provide technical support for the green and sustainable development in the local cotton-growing region. [Methods] Field experiments were conducted from 2022 to 2024 in Linqing City, Shandong Province. Using monocropped spring cotton (MFC) and monocropped short-season cotton (MSC) as controls, the annual yield, economic returns, and soil nutrient content dynamics of two double cropping patterns, intercropping of spring cotton with S. rugosoannulata (FC+SR), short-season cotton followed by S. rugosoannulata in succession planting (SC+SR), were systematically compared. [Results] Compared with MFC treatment, the seed cotton yields of FC+SR and SC+SR treatments significantly decreased by 7.7% and 14.2%, respectively. However, by harvesting S. rugosoannulata (fresh yield: 20.80-21.53 t·hm^-2), the system's net profit was significantly increased to 216 700-244 100 yuan·hm^-2, which was 43.3-48.8 times that of MFC treatment. The net profit of SC+SR pattern was 12.6% higher than that of the FC+SR pattern. Compared with monocropped cotton, the double cropping patterns combined with straw and S. rugosoannulata residue returning significantly increased the contents of alkali-hydrolyzable nitrogen, available phosphorus, and available potassium in the 0-20 cm, 20-40 cm, and 40-60 cm soil layers. And the improvement effect of the SC+SR pattern was generally superior to that of FC+SR. [Conclusion] The cotton-S. rugosoannulata double cropping system is feasible in the Yellow River Basin, with the short-season cotton followed by S. rugosoannulata in succession planting (SC+SR) being the preferred choice. This pattern achieved the recycling of field straw resources and synergistic enhancement of economic benefits and soil fertility, serving as an effective pathway for promoting high-quality agricultural development in the cotton-growing regions of the Yellow River Basin.

[Objective] This study aims to address the issues of impurity contamination in machine-picked seed cotton in Xinjiang and the low efficiency of manual sorting, we propose a highly efficient and precise method for detecting impurities in seed cotton to enhance cotton quality. [Methods] An improved CID-YOLO model is introduced based on YOLO v11. Firstly, a normalization-based attention mechanism module is introduced to enable the network to balance target channel features and pixel features while reducing parameter count and computational complexity, thereby improving detection accuracy. Secondly, according to the characteristics that the detected target is easy to appear at the edge, the lightweight adaptive convolution module is used to replace some convolution modules in the backbone network and neck network, which can better preserve the edge and structure information of the sampling phase, and effectively reduce the amount of parameters. Finally, an efficient layer aggregation network is used to replace the improved pyramid pooling module in the backbone network to enhance the ability of feature multi-scale extraction and information aggregation, so as to improve the perception performance of targets of different scale targets in complex background. [Results] Experimental results demonstrate that the CID-YOLO model achieves outstanding performance in seed cotton impurity detection, with a detection accuracy of 92.1%, recall of 89.5%, F₁ score of 90.8%, and mean average precision of 92.8%. Its overall recognition effectiveness significantly outperforms existing YOLO series models. [Conclusion] The proposed CID-YOLO method enables rapid and precise identification of drip irrigation tapes, colored impurities, cotton stalks, and plastic mulch in machine-picked seed cotton. It provides effective technical support for real-time seed cotton impurity detection and holds promising application prospects.

[Objective] This study aimed to explore the application potential of cotton-soybean intercropping in addressing prominent issues such as the intense conflict between grain and cotton for land, as well as soil degradation, in the cotton-growing areas of the Yellow River Basin. [Methods] The experiments were conducted in Binzhou City, Shandong Province, from 2023 to 2024. Different treatments were set up, including cotton monocropping (CK1), soybean monocropping (CK2), and five row ratio configurations of cotton-soybean intercropping (2 rows of cotton intercropped with 2 rows of soybean, 2 rows of cotton intercropped with 3 rows of soybean, 2 rows of cotton intercropped with 4 rows of soybean, 4 rows of cotton intercropped with 4 rows of soybean, and 4 rows of cotton intercropped with 6 rows of soybean, denoted as 2||2, 2||3, 2||4, 4||4, and 4||6). The effects of these intercropping patterns on soil nutrient content, crop agronomic traits and yield, fiber quality, land equivalent ratio (LER), and comprehensive economic benefits were studied. [Results] Compared with monocropping, the intercropping system increased the contents of alkali-hydrolyzable nitrogen and available phosphorus in the 0-20 cm soil layer between cotton rows. The 4||6 intercropping pattern was beneficial for increasing the soil organic matter content and total humus content in the 0-20 cm and 20-40 cm soil layers between cotton rows and soybean rows. At the boll-opening stage, the number of mature bolls per plant under the five intercropping treatments was significantly lower than that under CK1. At the maturity stage, compared with monocropping, the number of nodes and effective branches per plant of intercropped soybeans decreased. Compared with CK1, the intercropping patterns led to a reduction in the number of bolls per plant and boll weight; however, the seed cotton yield increased due to the higher harvest density. In 2023, the 4||6 treatment achieved the highest seed cotton yield, which was significantly 19.34% higher than that of CK1. In 2024, the 2||3 treatment had the highest seed cotton yield, showing a significant increase of 15.20% compared with CK1. There were no significant differences in cotton fiber quality indicators among different treatments. Compared with CK2, the soybean yield under the 4||4 and 4||6 patterns increased by 1.58% and 12.00%, respectively in 2023. In 2024, the soybean yield under the 2||3, 4||6, and 4||4 treatments increased by 17.76%-26.18%. In 2023, the 4||6 treatment had the highest LER (1.15) and the highest net income. In 2024, the 2||3 treatment achieved the highest LER (1.19) and the highest net income. [Conclusion] Cotton-soybean intercropping was beneficial for increasing seed cotton yield, land use efficiency, and net income. Among the tested intercropping patterns, the 4||6 and 2||3 patterns showed greater promotion potential in the cotton-growing areas of the Yellow River Basin.

[Objective] Forkhead box protein G1 (FOXG1), as a transcription factor, plays a crucial role in cell proliferation and differentiation. At present, the FOXG1 gene family has not been systematically studied in cotton. This research aimed to identify and analyze FOXG1 gene family in cotton. [Methods] FOXG1 gene family members were identified in cotton using bioinformatic approaches. Analyses were performed on the physicochemical properties, conserved motifs, and phylogenetic relationships of the corresponding proteins. The expression patterns of FOXG1 genes in Gossypium hirsutum and G. barbadense were investigated using transcriptome data. Preliminary functional exploration of the FOXG1 genes was conducted through association analysis between haplotypes of G. hirsutum FOXG1 genes and fiber quality traits, as well as via transgenic overexpression of GhFOXG1-4 gene in Arabidopsis thaliana. [Results] A total of 6, 5, 3, 3, 6, 6, 6, and 3 FOXG1 genes were identified in G. hirsutum, G. barbadense, G. raimondii, G. arboreum, G. tomentosum, G. mustelinum, G. darwinii, and G. herbaceum, respectively. These 38 FOXG1 proteins and 3 FOXG1 proteins of A. thaliana could be divided into 4 clades. GhFOXG1-1 was highly expressed in anther and ovule. GhFOXG1-2, GbFOXG1-1 and GbFOXG1-2 were highly expressed in anther, ovule and fiber. GhFOXG1-4 was highly expressed in ovule. GhFOXG1-4 and GhFOXG1-5 had 2 and 3 haplotypes, respectively. Significant differences in upper half mean length, breaking strength, and micronaire were observed among these haplotypes. The stem cell width of A. thaliana overexpressing GhFOXG1-4 gene was significantly larger than that of wild type. [Conclusion] A total of 38 FOXG1 genes were identified in 8 cotton species. The excellent haplotypes of some GhFOXG1 genes have the potential to synergistically improve fiber quality. GhFOXG1-4 positively regulates the stem cell width in A. thaliana, which lays a foundation for further study the function of FOXG1 family genes.

[Objective] Construct a yeast two-hybrid (Y2H) library of Gossypium barbadense, and screen for interacting proteins of GbbHLH130 using Y2H assays. [Methods] This study constructed a Y2H library of G. barbadense using the Gateway technique, and employed the Y2H system to screen for candidate proteins interacting with GbbHLH130. [Results] This study successfully constructed a G. barbadense Y2H library, with a second library capacity of 1.36 × 10⁷ CFU, and insert fragment length >1 000 bp, and a recombination rate of 100%. Using Y2H technology, 298 initial positive clones were screened, and the interaction between GbRAV1, GbHSFA1b, and GbbHLH130 was verified through Y2H assays. [Conclusion] This study successfully constructed a Y2H library of G. barbadense and preliminarily screened candidate interacting proteins for GbbHLH130. GbRAV1 and GbHSFA1b were verified to interact with GbbHLH130 through Y2H assays, suggesting that they may play a role in the biological process of response to drought stress mediated by GbbHLH130. However, their interaction mechanisms and specific roles in drought response need further research.

[Objective] This research aimed to study the effects of different amounts of carbon-containing organic fertilizer on cotton biomass, nutrient accumulation, yield, and soil nutrient content to provide a reference for local cotton production. [Methods] From 2022 to 2023, field experiments were conducted in Wusu City, Tacheng Prefecture, Xinjiang. Six treatments were set up: no fertilization (CK), no application of carbon-containing organic fertilizer (C0), and application of carbon-containing organic fertilizer at 400 kg·hm^-2, 800 kg·hm^-2, 1 200 kg·hm^-2, and 1 600 kg·hm^-2 throughout the cotton growth period (referred to as C400, C800, C1200, C1600, respectively). The effects of different amounts of carbon-containing organic fertilizer on the aboveground dry matter mass; accumulation and distribution of nitrogen, phosphorus, and potassium of cotton; yield; and soil nutrient content were analyzed. [Results] From 2022 to 2023, the dry matter mass, the accumulation of nitrogen, phosphorus, and potassium of cotton straw, fiber, cottonseed, and aboveground parts; and seed cotton yield all showed an overall upward trend with the increase of carbon-containing organic fertilizer application. The proportion of dry matter mass in fiber under C1600 treatment was higher than that in the other treatments. CK treatment exhibited the lowest proportion of nitrogen accumulation in straw and fiber but the highest proportion of nitrogen accumulation in cottonseed. Compared with C0 treatment, the application of carbon-containing organic fertilizer showed no obvious effect on the proportion of phosphorus and potassium accumulation in various aboveground parts of cotton. The seed cotton yield under C1600 treatment was highest, significantly increasing by 53.79%-83.34% and 8.95%-11.77%, respectively, compared with CK and C0 treatments. After harvesting cotton in 2023, the contents of organic carbon, nitrate nitrogen, ammonium nitrogen, available phosphorus, and available potassium in the 0-20 cm soil layer, as well as the content of available potassium in the 20-40 cm soil layer, all showed an upward trend with the increasing application rate of carbon-containing organic fertilizer. [Conclusion] Under the conditions of this experiment, the application of 1 600 kg·hm^-2 carbon-containing organic fertilizer is beneficial for increasing soil nutrient content, promoting cotton's uptake of nitrogen, phosphorus, and potassium; increasing cotton aboveground dry matter mass; and achieving the highest seed cotton yield.

[Objective] This research aimed to investigate the effects of different pruning methods on the content of storage substances in upland cottonseed. [Methods] A field trial was conducted in Kashgar Prefecture, Xinjiang, in 2023, using a split-plot design. The main plots consisted of two cotton varieties (J8031 and Yuanmian 8), while the subplots involved different pruning treatments: retaining 3, 5, 7, or 9 bolls per plant from the flowering and boll-setting stage to harvest (T1, T2, T3, and T4 treatments); removing vegetative branches during the budding stage(T5); removing axillary buds during the flowering and boll-setting stage (T6); removing vegetative branches from the initial flowering stage to the flowering and boll-setting stage (T7); removing empty branches during the late flowering stage and early boll-opening stage (T8); and topping during the full flowering stage to boll opening stage (T9). No pruning was used as the control treatment (CK). The contents of total protein, 19 amino acids, total fat, 25 fatty acids, and gossypol in cottonseeds were measured under different treatments. [Results] Under T1 to T9 treatments, the total protein and total fat contents in cottonseed of J8031 and Yuanmian 8 showed no significant difference compared with CK. Compared with CK, T5 treatment significantly increased the contents of phenylalanine, arginine, tyrosine, proline, and glycine in J8031, as well as the contents of methionine, phenylalanine, arginine, tyrosine, proline, cysteine, and hydroxyproline in Yuanmian 8, significantly reduced the content of methionine in J8031. T6 treatment significantly increased arginine, tyrosine, and serine contents in J8031, as well as phenylalanine, tyrosine, and hydroxyproline contents in Yuanmian 8, significantly reduced methionine content in J8031. Compared with CK, the contents of stearic acid, heneicosanoic acid, and linoleic acid in J8031, and the contents of palmitic acid and eicosadienoic acid in Yuanmian 8 all significantly increased under T2 treatment. The contents of myristic acid, arachidic acid, eicosapentaenoic acid, and oleic acid in J8031 under T7 and T9 treatments significantly decreased. Under T1 treatment, the contents of palmitic acid, hexanoic acid, eicosapentaenoic acid, and eicosenoic acid significantly increased in Yuanmian 8; while the oleic acid content in J8031 and Yuanmian 8 significantly decreased. Under T7 and T8 treatments, the contents of heneicosanoic acid, linoleic acid, palmitoleic acid, oleic acid, and eicosenoic acid in Yuanmian 8 significantly decreased. Under T3, T5, T7, T8, and T9 treatments, both total (-)/(+)-gossypol and free (-)/(+)-gossypol contents in J8031 were significantly higher than that in CK. Compared with CK, total (-)/(+)-gossypol content in Yuanmian 8 significantly increased under T8 treatment, while free (-)/(+)-gossypol content significantly decreased under the nine treatments from T1 to T9. [Conclusion] Compared with CK, pruning treatment had no significant effect on the total protein and total fat contents in cottonseed of J8031 and Yuanmian 8, but significantly influenced the contents of certain amino acids, certain fatty acids, and gossypol.

[Objective] Gossypium aridum exhibits excellent stress tolerance. Plant homeodomain (PHD) proteins play a crucial role in regulating plant responses to abiotic stress. This study aimed to mine PHD genes in the whole genome of G. aridum, and analyze their expression patterns under abiotic stress. [Methods] G. aridum genome was mined for PHD using bioinformatics methods. The physicochemical properties, conserved domains and motifs, phylogenetic relationships of PHD proteins, cis-acting elements and transcription factor binding sites in the promoter region were predicted and analyzed. The expression levels of GarPHD genes under salt, drought, and low-temperature stresses were analyzed using quantitative real-time polymerase chain reaction (qRT-PCR). [Results] A total of 38 GarPHD genes were identified in G. aridum. The PHD domain of GarPHD proteins contains the consistent sequence: X(0-1)-C-X(1-2)-C-X(8-13)-C-[DESANQ]-X(1-2)-C-X(4)-H-X(2)-C-X(9-16)-[WYF]-X-C-X(2)-C. PHD proteins of G. aridum, G. tomentosum, and G. barbadense were divided into 5 subgroups. The promoter regions of GarPHD contain cis-acting elements related to growth and development, plant hormones, and stress responses, as well as binding sites for 33 transcription factors. The qRT-PCR analysis revealed significant changes in the expression levels of certain GarPHD genes in response to salt, drought, and low-temperature stress. Specifically, GarPHD19 was found to respond to both low-temperature and drought stress, GarPHD31 responded to both salt and drought stress. [Conclusion] Thirty-eight PHD genes were identified in G. aridum. Some GarPHD responded to salt, drought, and low-temperature stress, which lays the foundation for further research on the function of GarPHD genes.

[Objective] This research aimed to investigate the effects of reclaimed water irrigation and different mulching methods on cotton growth, yield, and fiber quality. [Methods] A field experiment was conducted in Hutubi County, Changji Hui Autonomous Prefecture, Xinjiang in 2024. Six treatments were established: well water irrigation throughout the whole growth stage + straw mulching (T₁); reclaimed water irrigation throughout the whole growth stage + straw mulching (T₂); reclaimed water irrigation at critical water-demand stages (squaring stage and flowering and boll-setting stage) + straw mulching (T₃); reclaimed water irrigation throughout the whole growth stage + plastic film mulching (T₄); reclaimed water irrigation at critical water-demand stages + plastic film mulching (T₅); and well water irrigation throughout the whole growth stage + plastic film mulching (CK). Cotton plant height, stem diameter, leaf area index (LAI), yield traits, irrigation water use efficiency (IWUE), and fiber quality were compared across different treatments. The entropy-weighted technique for order preference by similarity to ideal solution (TOPSIS) method was used for comprehensive evaluation to select the optimal treatment. Meanwhile, the heavy metal contents in the soil and different cotton organs were determined and analyzed. [Results] During the flowering and boll-setting stage, and boll-opening stage, reclaimed water irrigation significantly increased plant height, stem diameter, and LAI compared with well water irrigation. The plant height, stem diameter, and LAI under straw mulching were greater than those under plastic film mulching; the T₂ treatment exhibited the maximum plant height, stem diameter, and LAI. T₂ also achieved the highest seed cotton yield, lint yield, and IWUE, and upper half mean length, breaking tenacity, breaking elongation, and micronaire of fiber of T₂ were superior to those of other treatments. Comprehensive evaluation using entropy-weighted TOPSIS showed that the T₂ treatment performed best. Compared with well water irrigation, reclaimed water irrigation significantly increased the contents of chromium (Cr) and lead (Pb) in the 0-60 cm soil layer and Cr content in cotton roots, stems, and leaves, while significantly reducing the arsenic (As) content in the 0-60 cm soil layer and cotton roots. However, the contents of mercury (Hg), cadmium (Cd), Cr, Pb, and As in soil and cotton plants under different treatments were all below the risk screening values. [Conclusion] Under the conditions of this experiment, the combination of reclaimed water irrigation throughout the whole growth stage and straw mulching showed the best comprehensive performance.

[Objective] This study aims to increase cotton yield and water use efficiency in southern Xinjiang under limited water resources. [Methods] The experiment was conducted using the cotton variety Tahe 2. In 2023, three spring drip irrigation quotas were set: T1 (600 m³·hm^-2), T2 (900 m³·hm^-2), and T3 (1 200 m³·hm^-2). In 2024, a conventional spring irrigation quota of 2 250 m³·hm^-2 was added as the control(CK). The effects of different drip irrigation quotas on soil water-salt changes, cotton physiological growth, and yield were studied. [Results] In the two-year experiment, the soil water storage in the 0-60 cm layer under the T2 treatment was the highest at all cotton growth stages, increasing by 1.01%-14.88% compared to T1, and by 1.25%-15.26% compared to T3. In 2024, the soil water storage in the 0-80 cm layer for all treatments followed the order of T3 > CK > T2 > T1. In 2023, the electrical conductivity in the 0-60 cm layer under T2 and T3 was lower than that of T1 by 6.08%-19.26% and 19.86%-32.96%, respectively. In 2024, the electrical conductivity in the 0-80 cm layer under T2 and T3 was reduced by 3.33%-25.81% compared to T1. Compared with T1 and T2, the T3 treatment showed a 10.54-19.95 percentage points higher seedling emergence rate, a 9.23%-23.54% increase in plant height, an 11.11%-23.87% increase in leaf area index, and a 26.32%-59.11% increase in fresh weight at the flowering and boll stages. The boll weight under the T3 treatment was 2.86%-8.51% higher than that under T1 and T2, and the seed cotton yield increased by 2.39%-10.24%. In 2024, compared to CK, the seedling emergence rate under T3 was 1.21 percentage points higher, and plant height, leaf area index, and fresh weight at the flowering and boll stages increased by 3.67%, 6.69%, and 0.55%, respectively. Compared to CK, the seed cotton yield under T1 was significantly reduced by 8.55%, while the yields under T2 and T3 did not show any significant difference. The irrigation water use efficiency for T1, T2, and T3 was significantly higher than that of CK, increasing by 27.38%, 24.30%, and 22.87%, respectively. The TOPSIS comprehensive evaluation showed that the drip irrigation method performed better, with 1 200 m³·hm^-2 being the optimal irrigation quota for cotton fields under drip irrigation. [Conclusion] It is recommended to adopt a 1 200 m³·hm^-2 drip irrigation quota in spring in southern Xinjiang, as this irrigation amount is beneficial for increasing soil water storage, promoting cotton growth, and improving seed cotton yield.

[Objective] This study aimed to analyze and clarify the biological function of Gossypium hirsutum GhVAS1, and to elucidate its regulatory mechanism underlying boll abscission. [Methods] Using the Arabidopsis thaliana VAS1 gene as a query sequence, two GhVAS1 homologs (GhVAS1-A05 and GhVAS1-D05) were identified and cloned from the upland cotton cultivar TM-1. Subsequently, phylogenetic analysis, conserved motif prediction and protein structure characterization of the cloned GhVAS1 genes were performed. The spatiotemporal expression patterns of GhVAS1 were analyzed by integrating RNA-sequencing (RNA-seq) data with quantitative real-time polymerase chain reaction (qRT-PCR) analysis. The subcellular localization of GhVAS1 was determined using a transient expression system in Nicotiana benthamiana. To assess the role of GhVAS1 in boll abscission, cotton leaf crumple virus (CLCrV)-mediated virus-induced gene silencing (VIGS) was employed in cotton plants. Endogenous levels of auxin (indole-3-acetic acid, IAA) and 1-aminocyclopropane-1-carboxylic acid (ACC) in abscission layer tissues were quantified, and the transcriptional profiles of abscission-related genes were analyzed. In parallel, heterologous overexpression of GhVAS1 in A. thaliana was conducted to validate its conserved regulatory role in organ abscission across plant species. [Results] Phylogenetic analysis revealed that the two GhVAS1 share a close evolutionary relationship with AtVAS1 and encode highly conserved proteins in G. hirsutum. GhVAS1 transcripts exhibited preferential accumulation in the abscission layer and were significantly and consistently upregulated in response to abscission-inducing signals. Subcellular localization assays demonstrated that both GhVAS1 proteins are localized to the nucleus and plasma membrane. VIGS-mediated silencing of GhVAS1 resulted in a significant reduction in cotton boll abscission, which was accompanied by a marked increase in endogenous IAA content and a concurrent decrease in ACC levels in abscission layer tissues. Consistently, the transcriptional levels of key ethylene biosynthetic genes (GhACS and GhACO) and cell wall hydrolysis-related genes (GhPG and GhCEL) were significantly downregulated in GhVAS1-silenced plants. In parallel, heterologous overexpression of GhVAS1 in A. thaliana accelerated floral organ abscission compared with wild-type plants. [Conclusion] GhVAS1 positively regulates boll abscission in cotton by coordinating the IAA-ethylene metabolic balance in abscission layer tissues and upregulating the expression of cell wall degradation-related genes, thereby promoting abscission layer cell separation and subsequent organ shedding.

[Objective] This study aimed to investigate the function of the GhMLO6 gene in cotton Verticillium wilt resistance and identify a candidate gene for disease resistance breeding in cotton. [Methods] Quantitative real-time polymerase chain reaction (qRT-PCR) was used to analyze the expression pattern of GhMLO6. The virus-induced gene silencing (VIGS) technique was employed to transiently silence GhMLO6 in cotton to study its function in Verticillium wilt resistance. Agrobacterium-mediated transient expression technology was applied to Nicotiana benthamiana to explore the subcellular localization of GhMLO6. [Results] The qRT-PCR results revealed that GhMLO6 presented the highest expression level in cotton roots, followed by stems and leaves. Compared with the control, infection with Verticillium dahliae significantly increased the expression level of GhMLO6 in roots. Compared with the control plants in which empty vectors were used, GhMLO6-silenced plants displayed a significant decrease in disease index and relative fungal DNA content. After stem recovery and cultivation, the accumulation of hyphae was reduced, and the resistance of cotton to Verticillium wilt was significantly increased. Transient expression analysis indicated that GhMLO6 localizes on the cell membrane. [Conclusion] GhMLO6 is localized to the cell membrane and performs a negative regulatory function in cotton Verticillium wilt resistance. Therefore materials with Verticillium wilt resistance could be obtained via gene editing technology.

[Objective] This study aims to analyze the effect of the Haloxylon ammodendron (C. A. Mey.) Bunge HaNAC12 gene on the fatty acid content and drought resistance of cotton, and to provide theoretical and technical guidance for cotton stress-resistant breeding. [Methods] The HaNAC12 gene was introduced into cotton through the cotton shoot apical meristem genetic transformation system. After molecular detection of T₀ and T₁ generation plants, the phenotypic and physiological indexes differences between transgenic and non-transgenic cotton were compared through drought stress experiments. [Results] After 30 days of natural drought stress (T30 treatment), the plant height of transgenic cotton was significantly increased by 11% compared with the non-transgenic control, and the degree of leaf wilting was less than that of the control. Physiological index analysis of cotton leaves under T30 treatment showed that the content of malondialdehyde in transgenic cotton was significantly 34% lower than that in the control, with less damage to the plasma membrane; the contents of soluble sugar, proline and chlorophyll were significantly 66%, 89% and 50% higher than those in the control, respectively, with stronger osmotic adjustment ability; the activities of superoxide, peroxidase and catalase dismutase were significantly 94%, 25% and 58% higher than those in the control, respectively, with stronger ability to scavenge reactive oxygen species. Under the T30 treatament, the expression levels of genes related to fatty acid metabolism, such as fatty acid synthase and desaturase, in transgenic cotton were significantly higher than those in the control after drought stress, and the content of free fatty acids in transgenic cotton was significantly 50% higher than that in non-transgenic cotton. There were no significant differences in leaf phenotypes and physiological and biochemical indexes between transgenic and non-transgenic cotton in the normal watering group. [Conclusion] The HaNAC12 may enhance the drought stress tolerance of cotton seedlings by promoting the synthesis and accumulation of fatty acids, providing new gene resources and material support for the genetic improvement of cotton drought resistance.

[Objective] The severe shortage of freshwater has severely restricted cotton production in the arid and semi-arid areas of Xinjiang, and water deficit during the key growth stages exerts an even more adverse effect on yield. Saline water supplemental irrigation can alleviate freshwater shortages, but its optimal salinity threshold remains unclear. This study investigated the effects of supplemental irrigation with saline water of different salinity levels on the photosynthetic characteristics and yield formation of cotton, aiming to determine the suitable salinity threshold for cotton supplemental irrigation in arid areas. [Methods] A two-year field experiment was conducted during the cotton growing seasons in 2023 and 2024. The conventional fresh water without supplemental irrigation was used as the control (CK, irrigation quota of 3 600 m³·hm^-2), and five saline water supplemental irrigation treatments were established: 3.5 g·L^-1 (S3.5), 5.0 g·L^-1 (S5), 6.5 g·L^-1 (S6.5), 8.0 g·L^-1 (S8), 9.5 g·L^-1 (S9.5). The saline supplemental irrigation regime consisted of one application at the bud stage (375 m³·hm^-2) and two applications at the boll-setting stage (375 m³·hm^-2 + 450 m³·hm^-2). The total irrigation amount was 4 800 m³·hm^-2 (including 1 200 m³·hm^-2 of saline water and 3 600 m³·hm^-2 of freshwater). Gas exchange parameters, chlorophyll fluorescence parameters in functional leaves after saline water irrigations, and yield components of cotton were measured. [Results] During the early boll-setting stage, the two-year average net photosynthetic rate (P_n) of treatments with salinity levels of S3.5, S5, and S6.5 increased by 6.89%-18.00% compared with CK, and the S3.5 treatment was significantly higher than CK. The transpiration rates (T_r) of the S3.5 and S5 treatments were significantly increased by 18.96% and 9.10%, respectively, compared with CK, and the stomatal conductances (G_s) were increased by 12.95% and 3.90%, respectively. After three saline water supplementary irrigations, the initial fluorescence (F₀) of the S9.5 treatment was significantly increased by 5.99% (in 2023) and 6.54% (in 2024) relative to CK, while the maximum photochemical efficiency (F_v/F_m) of the S3.5 treatment was significantly higher than that of the S9.5 treatment. The boll-leaf ratio of cotton was the lowest in the S3.5 treatment, with two-year values of 24.58 and 24.87, followed by the S5 treatment with values of 25.02 and 25.05. The two-year average seed cotton yield of treatments with salinity levels of 3.5-6.5 g·L^-1 significantly increased by 2.73%-12.67% compared with CK (5 721.00 kg·hm^-2). [Conclusion] Supplemental irrigation with saline water with a salinity level of 3.5-6.5 g·L^-1 can optimize the photosynthetic performance of cotton and achieve stable or increased yields. However, excessively high salinity level (>6.5 g·L^-1) is prone to cause photoinhibition, leading to a significant reduction in cotton yield. This study provides an important theoretical basis for determining the salinity threshold for saline water irrigation in arid areas.

[Objective] This study aims to investigate the effects of different tillage practices combined with straw returning on cotton growth, yield, and rhizosphere soil bacterial communities in a potato-cotton rotation system, so as to provide a scientific basis for optimizing farmland management and improving soil microecological health in this system. [Methods] The cotton cultivar Xiang X1107 was used as material. Four treatments were designed: no-tillage (NT), no-tillage with straw returning (NTS), rotary tillage (T), and rotary tillage with straw returning (TS). Growth-related traits and biomass of cotton plant at key growth stages, as well as yield and its components were measured. High-throughput sequencing of the 16S rRNA gene was used to analyze the diversity and composition of rhizosphere soil bacterial communities at the boll-opening stage of cotton, and functional prediction was performed using the Functional Annotation of Prokaryotic Taxa (FAPROTAX). [Results] Straw returning and tillage practice had no significant effect on cotton emergence rate. Compared with no-tillage treatments (NT and NTS), rotary tillage treatments (T and TS) significantly increased plant height, stem diameter, and biomass at the seedling stage, and significantly increased boll weight. Whereas no significant differences in seed cotton yield and boll number were detected among all treatments. Straw returning treatments (NTS and TS) significantly elevated the Shannon Wiener's diversity index, Chao1 index, and evenness index of rhizosphere bacterial communities, with NTS showing the highest values for all indices except the Shannon Wiener's diversity index. Principal coordinates analysis (PCoA) revealed that tillage practice was the primary factor driving the differentiation of bacterial community structure. Proteobacteria was the dominant phylum across all treatments. Straw returning (NTS and TS) significantly decreased the relative abundance of Proteobacteria, while significantly increased the relative abundances of Acidobacteriota and Actinobacteriota. At the genus level, no-tillage treatments (NTS and TS) enriched nitrogen-fixing-related genera including Burkholderia_Caballeronia_Paraburkholderia, Klebsiella, Bradyrhizobium, and Allorhizobium_Neorhizobium_Pararhizobium_Rhizobium complex, and FAPROTAX prediction confirmed a significant enhancement of nitrogen fixation function. Treatment enriched Pantoea and Pseudomonas, and increased the abundances of chemoheterotrophy and human pathogen all related functional groups, whereas TS treatment effectively reduced the risk of pathogenic bacteria. [Conclusion] NTS is conducive to maintaining soil microbial diversity, enhancing nitrogen fixation function, and reducing pathogenic bacteria risk, and is thus the recommended tillage mode in the potato-cotton rotation system. TS can serve as an alternative to promote early-stage growth and regulate microbial functions. Appropriate combination modes can be selected according to local soil conditions, ecological and economic objectives in agricultural production.