[Objective] This study aims to investigate the suitable planting density of different cotton varieties in southern Xinjiang and to provide a theoretical basis for the construction of high-yield cultivation model. [Methods] The experiment was conducted in Yuli County from 2023 to 2024, with five planting density levels: 9.0 plants·m^-2 (D1), 13.5 plants·m^-2 (D2), 18.0 plants·m^-2 (D3), 22.5 plants·m^-2 (D4), 27.0 plants·m^-2 (D5), and three cotton varieties: Xinluzhong 79 (C1), Xinluzao 73 (C2), and Xinshi 518 (C3). The optimal planting density was determined by measuring the cotton reproductive period, dry matter accumulation and distribution, and seed cotton yield. [Results] The growth period of cotton was prolonged as the density increased. With the increase of planting density, the maximum dry matter accumulation and maximum growth rate of vegetative organs, reproductive organs, and aboveground parts of C1 and C2 showed trends of increasing and then decreasing, peaking at D3. The average highest seed cotton yields were 6 458.66 kg·hm^-2 at D3 for C1, and 6 083.64 kg·hm^-2 at D3 for C2, respectively. For C3, the maximum dry matter accumulation and maximum growth rate of vegetative organs, reproductive organs, and aboveground parts continued to rise with the increase in planting density, and the highest seed cotton yield of 5 875.30 kg·hm^-2 was reached at D5. The planting density does not show a clear pattern in its effect on the time at which different organs reach their maximum dry matter accumulation and the time at which they achieve their maximum growth rate. [Condusion] For Xinluzhong 79 and Xinluzao 73 varieties, a planting density of 18 plants·m^-2 is suitable, while for Xinshi 518 variety, a high-density cultivation pattern of 27 plants·m^-2 is recommended.

[Objective] Transposable elements are a major driver of genome evolution, yet the functions of the gag gene family in upland cotton remain unclear. This study aimed to identify members of the gag gene family in upland cotton and analyze their structural characteristics, evolutionary relationships, and expression patterns to explore their potential roles in cotton growth, development, and stress responses. [Methods] Based on the TM-1 reference genome of upland cotton, gag gene family members were identified using HMMER software, NCBI-CDD database and the Pfam database. Bioinformatics tools were employed to analyze their physicochemical properties, subcellular localization, and chromosomal distribution. Phylogenetic trees were constructed using ClustalX and MEGA X. Cis-acting elements in promoter regions were predicted using PlantCARE website, and LTR transposon distribution was analyzed with RepeatMasker and LTR_retriever. Transcriptome data and quantiative real-time polymerase chain reaction were performed to analysis the expression patterns and functions of gag genes. [Results] A total of 166 gag genes was identified in upland cotton with significantly more genes in the A sub-genome than in the D sub-genome. Phylogenetic analysis divided the family into two major subfamilies (nine subgroups) with diverse gene structures, most of which are located in LTR transposons. Promoter analysis revealed abundant cis-acting elements related to cotton growth, development, hormone responses, and stress adaptation. Expression profiling showed that certain genes, such as Ghir_A09G013490 and Ghir_D04G004460, were highly expressed in specific tissues(e.g., ovules, fibers) or under stress conditions(e.g., high temperature, salt stress). [Condusion] The gag gene family exhibits significant diversity in upland cotton, with its evolution closely linked to LTR transposon activity. Some members may play roles in abiotic stress responses and seed development, offering potential targets for cotton genetic improvement.

This study mainly based on the Xinjiang Statistical Yearbook, the annual global supply and demand information of extra-fine cotton published by the International Cotton Advisory Committee (ICAC), combined with the data provided by agricultural departments of Xinjiang prefectures (autonomous prefectures), Development and Reform Commission of Xinjiang Uygur Autonomous Region, and other relevant institutions. The development status and its influencing factors of sea island cotton production in Xinjiang from 1955 to 2024 were analysed, and relevant recommendations were offered, to provide references for the sustainable development of sea island cotton production in Xinjiang. From 1955 to 2024, the planting area, yield per unit area, and total production of Xinjiang sea island cotton showed inter-annual fluctuations. From 1955 to 1990, the fluctuating growth trend was obvious, while in the 21st century, the planting area and total production fluctuated obviously. Sea island cotton varieties in Xinjiang have fully achieved independent breeding, with 88 excellent varieties developed, of which 20 varieties have been widely promoted and planted, supported by the planting technology of "short, dense, early, film, drip irrigation". It was analysed that the key factors influencing the production of sea island cotton include varieties, technology, economic returns, trade wars, and natural disasters. Sea island cotton production currently faces a historical low point in the 21st century in Xinjiang. To overcome these challenges, both technological support and policy guidance are needed.

[Objective] This research aimed to investigate the effects of different planting densities on the plant architecture and yield of cotton in southern Xinjiang, then to provide a theoretical basis for optimizing cultivation techniques. [Methods] From 2023 to 2024, field experiments were carried out in Yuli County, Xinjiang, with five kinds of cotton planting densities designed: 280 000 plants·hm^-2 (D1), 220 000 plants·hm^-2 (D2), 180 000 plants·hm^-2 (D3), 130 000 plants·hm^-2 (D4), and 90 000 plants·hm^-2 (D5). The cylinder-type variety, Xinluzhong 79 (T1), and the tower-type variety, Xinshi 518 (T2) were taken as research objects. The effects of different planting densities on plant height, internode length of fruiting branches, insertion angle and azimuth angle of fruiting branches and leaves, leaf area index (LAI), and yield traits of cotton were analyzed. [Results] The plant height of the T1 variety was the highest under D3 or D4 treatment, and the plant height of the T2 variety was the highest under D4 treatment. With the decrease of cotton planting density, the average internode length of fruiting branches of the T1 and T2 varieties gradually increased, and the insertion angle of fruiting branches in the lower, middle, and upper parts increased as a whole. Under D4 or D5 treatment, the leaf insertion angle in the lower, middle, and upper parts of the two varieties was the largest. Under different cotton planting densities, there were no significant differences in the leaf insertion angle in the lower, middle, and upper parts of the T1 variety; there were no significant differences in the fruiting branch azimuth angle in the lower part and leaf azimuth angle in the middle and upper parts of the T1 and T2 varieties. The LAI of the T1 and T2 varieties was the largest under D4 and D3 treatments, respectively. With the increase of cotton planting density, the number of bolls per plant decreased. T1 and T2 varieties showed the highest seed cotton yields under D3 and D1 treatments, respectively. [Condusion] Different planting densities affect the plant architecture and yield of cylinder- and tower-type cotton varieties. The suitable planting densities for Xinluzhong 79 and Xinshi 518 in southern Xinjiang are 180 000 plants·hm^-2 and 280 000 plants·hm^-2, respectively.

[Objective] This research aimed to investigate the function of the ghr-miR394-GhFBX6 module in cotton resistance to Verticillium wilt and to provide candidate genes for cotton disease-resistant breeding. [Methods] The expression patterns of ghr-miR394a and GhFBX6 were analyzed using quantitative real-time polymerase chain reaction (qRT-PCR). Virus-induced gene silencing (VIGS) was employed to transiently silence ghr-miR394a and GhFBX6 individually, and in combination with the transient overexpression of ghr-miR394a in cotton, to investigate their roles in resistance to Verticillium wilt. The regulatory effect of ghr-miR394a on GhFBX6 was analyzed using the 5'-RNA ligase-mediated rapid amplification of cDNA ends (5' RLM-RACE) technique combined with a luciferase (LUC) reporter system. [Results] qRT-PCR analysis revealed that ghr-miR394a was highly expressed in cotton leaves, followed by stems and roots. Compared with the water treatment, inoculation with Verticillium dahliae significantly downregulated the expression level of ghr-miR394a in roots, while significantly upregulated the expression level of GhFBX6. Compared with control plants, transient silencing of ghr-miR394a in cotton resulted in a significantly reduced disease index and rate of diseased plants, and less fungal biomass accumulation in stem segments during recovery culture, indicating enhanced resistance to Verticillium wilt. In contrast, transient overexpression of ghr-miR394a or silencing of GhFBX6 led to decreased resistance to V. dahliae, as evidenced by a significantly higher disease index and rate of diseased plants, increased fungal biomass accumulation in stem segments of ghr-miR394a-overexpressing plants, and more severe browning of vascular bundles in GhFBX6-silenced plants. The results from 5' RLM-RACE and the LUC reporter system demonstrated that ghr-miR394a inhibits the expression of GhFBX6 at the post-transcriptional level. [Conclusion] ghr-miR394a targets and inhibits the expression of GhFBX6. ghr-miR394a and GhFBX6 play negative and positive regulatory roles, respectively, in the cotton response to Verticillium wilt.

[Objective] This study aimed to explore the biological functions of one of the aluminum-activated malate transporter (ALMT) family genes, GhALMT10, in the drought resistance of cotton, thereby establishing a foundation for a deeper understanding of the mechanisms of drought resistance in cotton. [Methods] The coding sequence of GhALMT10 gene was amplified from Gossypium hirsutum TM-1 by polymerase chain reaction (PCR), followed by bioinformatics analysis. The expression patterns of this gene in various cotton tissues, as well as under drought stress, were assessed using quantitative real-time PCR (qRT-PCR). Additionally, the biological function of this gene in cotton's response to drought stress was preliminarily verified using virus-induced gene silencing (VIGS) technology. [Results] The coding region of GhALMT10 spans 1 401 bp, encoding a protein composed of 466 amino acid residues, which is predicted to be stable and hydrophobic. Phylogenetic analysis indicated that GhALMT10 is closely related to GrALMT10, GaALMT10-like, HsALMT10, and TcALMT10. Results by qRT-PCR indicated that GhALMT10 is expressed in cotton roots, stems, and leaves, with the highest expression level observed in the roots. Compared with the control treatment with clear water, the expression level of GhALMT10 was low at 3 h of drought sress, and then significantly increased at 6 h and 9 h of drought stress treatment, while it significantly decreased at 24 h. Furthermore, the survival rate of GhALMT10-silenced cotton plants was significantly higher under drought stress compared with the negative control plants. The water loss rate of detached leaves was significantly reduced, the chlorophyll content in leaves after drought treatment was significantly increased, and the malondialdehyde content was significantly decreased in GhALMT10-silenced cotton plants. [Condusion] The drought tolerance of GhALMT10-silenced plants was significantly enhanced, indicating that GhALMT10 gene negatively regulates drought resistance in cotton.

Transgenic crops, including insect-resistant cotton, have been widely cultivated globally, yielding significant economic and social benefits. Cotton is the foremost natural fiber source and one of the most important cash crops worldwide. The genetic transformation technology mediated by Agrobacterium tumefaciens, based on somatic embryogenesis or organogenesis, has become the primary method for obtaining transgenic plants. Particularly for cotton, a crop that typically regenerates through somatic embryogenesis, this process is not only crucial for the application of modern biotechnology in cotton, but also plays a vital role in genetic improvement and variety innovation in cotton. However, cotton somatic embryogenesis is a complex process; although its regulatory mechanisms have been extensively studied, genotype-dependence and low regeneration efficiency remain significant challenges in cotton genetic transformation. This article provides an overview of the research progress in cotton somatic embryogenesis, summarizing the status of the cotton somatic embryogenesis system, including key influencing factors and molecular mechanisms, and offers perspectives on future research in this area.

[Objective] This research aimed to investigate the optimal row spacing and planting density of mechanically harvested cotton in the Yangtze River Basin. [Methods] Field trials were conducted in Changsha, Yueyang, and Hengyang Cities in Hunan Province in 2024, using the JX0010 cotton variety as the experimental material. The main plot included three row spacing treatments: 90 cm (L1), 83 cm (L2), and 76 cm (L3), while the subplot had three planting density treatments: 60 000 plants·hm^-2 (D1), 75 000 plants·hm^-2 (D2), and 90 000 plants·hm^-2 (D3). The plant architecture, aboveground dry matter mass, net photosynthetic rate (P_n), chlorophyll content (soil and plant analyzer development, SPAD value), leaf area index (LAI), and yield traits were compared under different treatments. [Results] At the same row spacing, as planting density increased, plant height tended to increase, while the number of fruiting branches, stem diameter, and length of the fourth fruiting branch tended to decrease. The height of the first fruiting branch was higher under L1D3 treatment. At the full squaring stage, the aboveground dry matter mass per plant tended to increase with the increasing of planting density at the same row spacing. The dry matter mass of stems, leaves, reproductive organs, and whole plant were higher under L1D3 treatment at the full squaring stage, full flowering stage, full boll-setting stage, and boll opening stage. At the full flowering stage and full boll-setting stage, P_n was higher under the D2 treatment at the same row spacing; at the boll opening stage, P_n tended to increase with the increasing of planting density, and P_n was higher under L1D3 treatment. At the same row spacing, SPAD value and LAI (except for the L1 treatment in Changsha at the full squaring stage) increased with the increasing of planting density from the full squaring stage to boll opening stage. The L1D3 treatment had the highest number of bolls per plant. Under the same row spacing, seed cotton yield and lint yield increased with the increasing of planting density, with L1D3 treatment showing the highest seed cotton yield and lint yield, which were significantly higher than the other seven treatments(expcept L2D3 treatment) at both Yueyang and Hengyang test sites. [Condusion] Under the conditions of this experiment, the optimal row spacing for JX0010 cotton is 90 cm, and the optimal planting density is 90 000 plants·hm^-2.

[Objective] This study aims to evaluate the effects of different arbuscular mycorrhizal fungi (AMF) on cotton growth under salt stress, and screen for AMF strains that promote cotton growth more efficiently under salt stress. [Methods] Using the main varieties of Zhongmian 113 and Tahe 2 in Xinjiang as materials, the effects of inoculation with different AMF on cotton seedling growth, dry matter accumulation, gas-exchange parameters, nitrogen, phosphorus, potassium accumulation, and K/Na ratio were studied. The optimal strain was determined through a comprehensive evaluation method based on entropy weight. [Results] The results showed that AMF inoculation significantly promoted the growth of cotton seedlings under salt stress. Compared with cotton plant without AMF inoculation, the plant height of Zhongmian 113 inoculated with different AMF strain significantly increased by 62.13%-89.55%, the dry matter mass per plant significantly increased by 122.58%-141.94%, the root-shoot ratio decreased by 20.38%-49.34%, the aboveground water content increased by 8.40%-12.65%, and the root water content increased by 9.78%-15.61%; Compared with cotton plant without AMF inoculation, the plant height of Tahe 2 inoculated with different AMF straub was significantly increased by 70.23%-103.88%, the dry matter mass per plant was significantly increased by 80.95%-188.10%, the root shoot ratio was reduced by 42.40%-59.28%, the aboveground water content was increased by 5.88%-11.11%, and the root water content was increased by 12.05%-18.51%. Inoculation of AMF enhanced the absorption of nitrogen, phosphorus and potassium by cotton. Compared with no inoculation, the K/Na ratio in shoots of Zhongmian 113 and Tahe 2 increased by 53.81%-102.96% and 40.54%-122.10%, respectively. The effects of inoculating different AMF showed significant difference. The comprehensive score results showed that the optimal strain of Zhongmian 113 was XJ04B, and the optimal strain of Tahe 2 was XJ02. [Condusion] Inoculation with different AMF can significantly improve the growth of cotton seedlings under salt stress, and different strains have different performances in promoting cotton growth under salt stress. This experiment provides a reference for screening effective AMF strains in cotton under salt stress environment.

[Objective] In order to provide technical guidance and a theoretical basis for the safe application of insect-resistant cotton in production, the effect of exogenous growth regulator on insecticidal protein content of Bt cotton and its underlying physiological mechanism under high temperature and drought stress were studied. [Methods] The transgenic insect-resistant cotton cultivar Sikang 1 (SK-1) and hybrid cultivar Sikang 3 (SK-3) were used as experimental materials, the daily temperature of 32 ℃ and 75% field capacity were used as control, and the artificial climate chamber was subjected to different high temperature levels (34 ℃ and 38 ℃) and drought stress (50% and 60% field capacity) during the peak flowering period in 2021-2022. After 7 days of stress, cotton plants were sprayed with water (W), 200 mg·L^-1 salicylic acid (SA), and 20 mg·L^-1 mepiquat chloride (DPC), respectively. Three days later, the boll shells were sampled to determine the activities of glutamic oxaloacetate transaminase (GOT), glutamate pyruvate aminotransferase (GPT), glutamine synthetase (GS), glutamate synthase (GOGAT), nitrate reductase (NR), protease and other key enzymes of nitrogen metabolism, as well as soluble protein and free amino acid content. [Results] High temperature and drought stress inhibit the content of Bt protein in the boll shells of two tested varieties, while treatments with SA and DPC can alleviate this inhibitory effect. The Bt protein content under SA or DPC treatments is significantly higher than that of W treatment under various stress conditions, with the increase in SA treatment being more pronounced. The Bt protein content remains lower than that under the non-stressed control. In 2021, the Bt protein content in SK-1 treated with SA and DPC after heat and drought stresses increased by 51.3%-104.0% and 22.0%-85.4%, respectively, compared with the W treatment. In 2022, the increase was 14.7%-91.1% and 4.5%-67.8%. In SK-3, the Bt protein content in 2021 increased by 46.4%-98.3% and 22.9%-60.4% under SA and DPC treatments after heat and drought stresses, respectively, compared with the W treatment. In 2022, the increase was 18.8%-77.4% and 14.6%-57.6%, respectively. Among the varieties, SK-1 showed a more significant response to SA and DPC, with a higher increase in Bt protein content than that of SK-3. Physiological mechanism studies showed that SA and DPC treatments after heat and drought stresses significantly increased the activities of GPT, GOT, GOGAT, and NR, as well as the soluble protein content in SK-1 and SK-3. They also significantly reduced the free amino acid content, peptidase, and protease activities. Compared with the W treatment in 2021, SA and DPC treatments increased GOT activity in SK-1 by 70.3%-104.2% and 36.7%-61.9%, GPT activity by 58.2%-231.2% and 27.7%-88.9%, GS activity by 167.9%-197.3% and 79.7%-139.4%, NR activity by 22.4%-53.6% and 7.6%-42.8%, soluble protein content by 11.3%-40.6% and 7.5%-20.3%, while free amino acid content decreased by 15.6%-23.2% and 6.3%-14.1%, and protease activity decreased by 5.5%-13.5% and 2.7%-10.5%, respectively. The trend of changes in the indicators of SK-1 in 2022 was consistent with that in 2021. In the two-year experiment, SK-3 showed similar performance to SK-1. Overall, the effects of SA on the above indicators were superior to those of DPC. Stepwise regression analysis further indicated that NR activity, free amino acid content and GS activity was a key index to reflect the content of insecticidal protein in Bt cotton boll shell after growth regulator treatment under high temperature and drought stress. [Condusion] Spraying SA and DPC can enhance the activity of enzymes related to protein synthesis, reduce the activity of proteases and peptidases, and decrease the content of free amino acids. The primary mechanism is to enhance the capacity of protein synthesis, thereby increasing the Bt protein content in the boll shell of Bt cotton after high temperature and drought stress. Additionally, the effect of SA was better than DPC. This provides theoretical and practical guidance for the safe application of insect-resistant cotton.

[Objective] The study aimed to examine the effects of nitrogen, phosphorus, and potassium fertilizers on soil nutrient contents, cotton growth, and yield-related traits in the arid and nutrient-deficient Heilonggang region. [Methods] The experiment was conducted from 2022 to 2024 at the Weixian Experimental Station of the Cotton Research Institute, Hebei Academy of Agriculture and Forestry Sciences. A randomized block design was adopted with five treatments: no fertilizer, conventional fertilization, nitrogen deficiency, phosphorus deficiency, and potassium deficiency. Soil total nitrogen, alkali-hydrolyzable nitrogen, available phosphorus, and available potassium contents were measured after cotton harvest. At the square stage, early flowering stage, peak boll stage, and boll opening stage, dry matter accumulation of aboveground parts and plant nutrient contents were determined, and fertilizer utilization efficiency was calculated. Boll number per plant were counted on July 15, August 15, and September 10. The boll weight and lint percentage were measured after harvest, and the seed cotton yield and lint yield were calculated. [Results] The effects of nitrogen deficiency on soil total nitrogen and alkali-hydrolyzable nitrogen content were not significant. In the three-year experiment, the phosphorus deficiency treatment significantly reduced soil available phosphorus content by 8.5%, 14.6%, and 19.9%, compared with conventional fertilization, while potassium deficiency treatment significantly reduced available potassium content by 10.3%, 18.9%, and 24.6%, respectively. Compared with conventional fertilization, nitrogen uptake of aboveground parts of cotton in the nitrogen deficiency treatment significantly decreased by 35.7%, 35.4%, and 47.1%, while phosphorus uptake of aboveground parts of cotton in the phosphorus deficiency treatment showed no significant difference, and potassium uptake of aboveground parts of cotton in the potassium deficiency treatment significantly decreased by 15.3%, 13.0%, and 21.1% in 2022, 2023, and 2024, respectively. For agronomic efficiency, fertilizer contribution rate, and apparent utilization rate, nitrogen was the most efficient, followed by potassium, with phosphorus showing near-zero efficiency. Seed cotton yield in the nitrogen deficiency treatment significantly decreased by 5.5%, 13.1%, and 25.7%, while phosphorus deficiency had no significant effect on yield, and potassium deficiency led to a reduction of 3.1% over three years. [Conclusion] In the arid and nutrient-deficient Heilonggang region, fertilizer strategy should follow the principle of "applying efficient nitrogen, moderating potassium use, and reducing phosphorus".

[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 comprehensively evaluate the drought resistance of major cotton cultivars in southern Xinjiang, screen drought resistance indicators, and identify superior drought-resistant cultivars (lines). [Methods] A sand culture experiment was conducted using 15% PEG6000 to simulate drought stress on 15 cotton cultivars from southern Xinjiang. Phenotypic and physiological traits were investigated, and drought resistance coefficients were calculated. Comprehensive evaluation of drought resistance was performed through correlation analysis, principal component analysis (PCA), entropy-weighted TOPSIS method, and cluster analysis. A multiple stepwise regression model was established to optimize the evaluation system for drought resistance. [Results] Compared with the control, drought stress reduced the germination energy (GE), germination index (GI), root number (RN), main root length (MRL), hypocotyl length (HL), fresh weight (FW), and dry weight (DW) by over 30%, with HL showing the most significant decline (50.55%) and hypocotyl diameter (HD) the least (24.66%). Conversely, superoxide dismutase (SOD) and peroxidase (POD) activities, along with malondialdehyde (MDA) content, increased by over 20%. PCA condensed the original 12 indicators into two independent comprehensive factors, explaining 82.80% of variance, and identified five key drought resistance indicators during germination: MDA, SOD, DW, HD, and GR. Using entropy-weighted TOPSIS, a comprehensive drought resistance index was determined, and cluster analysis classified the 15 cultivars into four drought resistance types, including three high drought-resistant cultivars (Tahe 2, Zhongmian 113, and Xinluzhong 40), four moderate drought-resistant cultivars (Zhongmian 88, CCRI 979, Xinluzhong 61, and Jiumian 20), four drought-tolerant resistant cultivars (Xinluzhong 88, Zhongmian 619, Zhongmian 96A, and Zhongshengmian 17), and four drought-susceptible cultivars (Xinluzao 50, Xinluzhong 67, JBK16, and Xinluzhong 37). A reliable regression model for drought resistance evaluation was established: I=0.74-0.51C_MDA+0.15C_SOD+0.20C_DW+0.24C_HD+0.45C_GE, with a coefficient of determination of 0.99. [Conclusion] High drought-resistant cultivars exhibited significantly lower stress impacts and higher antioxidant capacity compared to sensitive ones. The entropy-weighted TOPSIS method identified Tahe 2 as the most drought-resistant cultivar. This study established a precise and efficient drought resistance evaluation system, providing a theoretical and technical support for cotton breeding and cultivation under drought conditions.

[Objective] This study aimed to investigate the effects of different defoliants on the seed vigor and storage substance content of machine-harvested cotton seeds with different maturities, providing references for the rational selection of defoliants in cotton production. [Methods] Field experiments were conducted in Shihezi City, Xinjiang, from 2020 to 2021. The main plot involved the application of two different defoliants: Ruituolong and Yeluokong. The subplots included two cotton materials: an early-maturing variety, Shidamian 268 (S268), and a late-maturing line, Shidamian 451 (S451). On September 27, cotton bolls that had developed for 30 d, 35 d, 40 d, 45 d, and 50 d on August 31 (the first application of defoliant) were harvested. Naturally-opened cotton bolls before defoliant application served as the control (CK). Seed coat color was observed, and seed index, seed specific weight, oil content, and protein content were measured. Seed germination percentage, germination potential, germination index, and vigor index were determined at 18 ℃ and 28 ℃. [Results] Compared with CK, the white seed rate (the proportion of immature seeds) of 30-day bolls and 35-day bolls of S268 significantly increased under Ruituolong and Yeluokong treatments; while the black-brown seed rate (the proportion of mature seeds), seed index, seed specific weight, protein content, oil content, germination percentage, germination index, and vigor index of cotton seeds all significantly decreased in 2020 and 2021. For S451, the white seed rate of bolls at 30 d, 35 d, and 40 d significantly increased; while the black-brown seed rate, seed index, seed specific weight, protein content, oil content, germination percentage (except for the 40-day bolls), germination potential (except for the 40-day bolls at 28 ℃), germination index, and vigor index of seeds all significantly decreased. After spraying Ruituolong and Yeluokong, there were no significant differences in the black-brown seed rate, germination percentage, and germination potential for 45-day and 50-day cotton bolls of S268 and S451 compared with CK; as well as the seed oil content and protein content of 50-day cotton bolls compared with CK. For S268 and S451, compared with Ruituolong, the black-brown seed rate of 30-day bolls, seed index of 50-day bolls, protein content of 35-day bolls, seed germination index of 35-day bolls at 28 ℃, and vigor index of 40-day bolls at 18 ℃ all significantly decreased. [Conclusion] Under the conditions of this experiment, the superior defoliant was Ruituolong. Spraying Ruituolong had a relatively minor impact on seed vigor and the content of storage substances of 45-50 days cotton bolls.

[Objective] Cotton yield prediction is an important part of cotton production management in our country. The accuracy of boll detection during the boll-opening stage directly affects the precision of yield estimation. In order to solve the problem that the computational complexity of existing cotton boll detection models increases significantly due to the pursuit of detection accuracy, this study proposes a lightweight cotton boll detection model, Slim-YOLOv8n, based on improved YOLOv8n. [Methods] This model takes YOLOv8n as its main framework. On one hand, it integrates a lightweight cross-scale feature fusion network in the neck structure to effectively reduce the dimensionality of multi-scale feature fusion and lower computational complexity. On the other hand, it reconstructs the detection head through reparameterized convolution and the idea of sharing, designing a reparameterized head and a two-stage feature processing stream to maintain accuracy while achieving model lightweighting. [Results] Experimental results show that this model achieves a detection accuracy of up to 98.20%. Compared with the YOLOv8n model, it reduces the number of parameters by 44.84%, computational cost by 39.51%, and model size by 43.34%, verifying the superiority of the model improvement. [Conclusion] Slim-YOLOv8n fully meets the dual demands of high accuracy and lightweighting for boll detection tasks, providing strong technical support for the efficient and precise detection of bolls at the boll-opening stage in cotton yield prediction.

[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] 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] This study aimed to analyze the influencing factors of farmers' participation in the futures market, and provide reference for using the futures market to promote the development of the cotton industry. [Methods] A theoretical analysis framework was constructed along the lines of "risk aversion motivation→futures function cognition→futures market participation willingness→futures market participation behavior". The ordered Logit model and multinomial Logit model were comprehensively used to analyze the influencing factors of cotton farmers' futures market participation willingness, and the Logit model was further used to discuss the influence of social capital and intermediary organizations. [Results] The results showed that 70% of farmers have heard of the futures market, but only 5% of farmers participate in the futures market. Farmers' resource endowments, such as education level, planting scale, age, as well as market risk avoidance motivation, futures function cognition, social capital, and intermediary organization development, have important impacts on cotton farmers' participation in the futures market. [Conclusion] Currently, the proportion of farmers participating in the futures market is still very low. The main factors that inhibit cotton farmers from participating in the futures market are insufficient motivation to avoid market risks, unclear understanding of futures functions, lack of demonstration guidance and social capital, and immature development of intermediary organizations.

[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.