Cotton straw is a by-product of cotton production and an important renewable biomass resource, and the study on its comprehensive utilization is of great significance to optimize energy structure and achieve 'dual carbon' goals. Due to the structural differences, the successful application methods of corn, wheat, and rice straw cannot be directly applied to cotton straw. Traditional treatment and application of cotton straw cause resource waste and environmental pollution. Therefore, it is essential to enhance the comprehensive utilization of cotton straw to improve agricultural waste utilization efficiency, optimize energy structure, and reduce environmental pollution. From the perspective of enhancing the comprehensive utilization efficiency of cotton straw, this article summarizes various utilization modes, including straw returning to the field, using them as feed, energy substrate, and raw material, and prospects the future multiuse of cotton straw which will provide methodological reference and research ideas for the diversified utilization of cotton straw.

[Objective] This research aims to study the effects of delayed sowing on cotton root growth and development characteristics and yield, so as to provide a basis for the timely sowing of cotton in the cotton planting area of the Yellow River Basin. [Methods] A field experiment was carried out at Weixian Experimental Station of Hebei Agricultural University from 2022 to 2023. Two treatments were set as conventional sowing date (15 April) and delayed sowing date (1 May). And the effects of delayed sowing on the root distribution, root growth rate, root-shoot ratio, dry matter accumulation, and yield of a cotton variety Jinongda 23 were analyzed. [Results] Compared with the conventional sowing date, under the delayed sowing condition, the maximum growth rate of cotton root length and root biomass increased by 2.92-5.35 cm·d^-1 and 0.40-0.76 mg·d^-1, respectively. The proportion of cotton roots in deep soil increased, with root length and biomass in the 30-60 cm soil layer increased by 2.99-3.55 percentage points and 3.94-4.42 percentage points, respectively. There was no obvious difference in aboveground biomass and root-shoot ratio in the late growth stage of cotton. The boll capacity of root system significantly decreased by 6.43%-17.69%. There was no significant difference in seed cotton yield in 2022. In 2023, the number of bolls per unit area and seed cotton yield increased significantly by 9.72% and 7.66%, respectively. Correlation analysis showed that root length density in 0-60 cm soil layer, root biomass density in 0-60 cm soil layer, maximum growth rate of root length, and the proportion of root length in 30-60 cm soil layer are extremely significantly correlated with seed cotton yield. [Conclusion] Delaying the sowing date (1 May) in cotton planting area of the Yellow River Basin can enhance the absorption function of cotton roots by increasing the growth rate of roots, the proportion of root length and biomass in deep soil layers, so as to ensure the accumulation of aboveground dry matter and promote the high yield of cotton.

[Objective] This study aims to perform genome-wide asscciation study of cotton yield traits, such as lint percentage (LP) and boll weight(BW), and to mine the candidate genes, and may be helpful for improving cotton yield through molecular marker-assisted selection and molecular design breeding. [Methods] Genome-wide association study was performed using 300 upland cotton germplasms resequencing (10×) data and 3 055 642 high-quality single nucleotide polymorphism (SNP) for LP and BW in five environments and best linear unbiased predictive value (BLUP) for two years to detect significant association loci and candidate genes. [Results] The cotton LP and BW showed wide variations in different environments, with an average coefficient of variation of 9.40% and heritability of 92.81% for LP, and an average coefficient of variation of 11.96% and heritability of 86.67% for BW. BW is significantly positively correlated in different environments. It’s the same with LP. Population structure analysis, principal component analysis, and phylogenetic analysis classified the 300 upland cotton lines into six subgroups. Genome-wide association study detected a total of 223 quantitative trait locus (QTL) associated with LP and 89 QTL associated with BW. The three stable QTL qLP_Gh5.18, qLP_Gh12.43, and qLP_Gh17.2 screened in LP were further analyzed, and 17 related candidate genes were found. Two stable QTL qBW_Gh7.5 and qBW_Gh19.5 related to BW were further analyzed, and 8 related candidate genes were identified. [Conclusion] Five stable QTL were identified in 300 up land cotton lines associated with cotton LP and BW, and a total of 25 candidate genes related to LP and BW were mined.

[Objective] This study aims to provide a theoretical basis for molecular breeding of disease-resistant cotton by cloning Gh_D11G050000 gene, and to analyze its function and mechanisms in cotton resistance to Verticillium wilt. [Methods] Bioinformatic method was utilized to analyze the sequence characteristics and phylogenetic relationship of Gh_D11G050000. Quantitative real-time polymerase chain reaction (qRT-PCR) was employed to investigate the expression pattern of this gene, and it's expression level changes after infected by Verticillium dahliae. The function of this gene was validated using virus-induced gene silencing (VIGS) technique. Transcriptome sequencing analysis and the detection of relative expression levels of related genes were conducted to explore the mechanisms of disease resistance. [Results] Gh_D11G050000 exhibited close relationship with Gh_A11G049600 and Gr_11G034620 protein. qRT-PCR analysis revealed that Gh_D11G050000 was highly expressed in cotton roots, and the expression level of Gh_D11G05000 was significantly increased after V. dahliae infection. Gh_D11G050000 silenced cotton plants showed reduced resistance against V. dahliae, characterized by aggravated browning of stem vascular bundles, increased the number of stem segments with bacterial propagation, as well as significantly increased the rate of diseased plants and disease index. Transcriptome analysis combined with qRT-PCR demonstrated that Gh_D11G050000 silenced cotton plants showed decreased transcription levels for several genes in jasmonic acid (JA) signaling pathway, ethylene (ET) signaling pathway, and lignin synthesis pathway. [Conclusion] Gh_D11G050000 positively regulates cotton resistance to Verticillium wilt by influencing the expression of several genes involved in lignin synthesis, JA, and ET signaling pathways.

[Objective] This study aims to analysis the effects of partial organic substitution for chemical fertilizer on soil and cotton root growth in different continuous cotton fields in Xinjiang, and to reveal the optimal proportion of organic fertilizer dosage, so as to provide reference for the rational application of fertilizers in continuous cotton fields in Xinjiang. [Methods] The cotton were planted in the grey desert soil and aeolian sandy soil, two common soil types of cotton fields in Xinjiang, and decomposed farm chicken manure was used as organic fertilizer, and setting up three fertilizer treatments: T1 treatment, 100% chemical fertilizer; T2, 80% chemical fertilizer + 20% organic fertilizer (2 250 kg·hm^-2 organic fertilizer); T3, 60% chemical fertilizer + 40% organic fertilizer (4 500 kg·hm^-2 organic fertilizer). The experiments were conducted using polyvinyl chloride pipes to study the effects of partial organic substitution for chemical fertilizer on the physical and chemical properties of cotton soil at the cotton budding stage and boll-opening stages, the morphological and physiological characteristics of cotton roots, as well as the biomass and yield of cotton. Principal component analysis and regression analysis were conducted on all indicators by using the comprehensive membership function method, to comprehensively evaluate the overall impact of different proportions of organic fertilizer and chemical fertilizer combinations on the soil-cotton system. [Results] Both T2 and T3 treatments significantly increased the total nitrogen content and available phosphorus content in grey desert soil and aeolian sandy soil. For grey desert soil, compared with T1, T2 treatment increased the total phosphorus content of the soil by 14.7% and 30.3%, and increased the available phosphorus content by 138.7% and 202.6% during the budding stage and boll-opening stage, respectively. For grey desert soil, compared with T1, T3 treatment increased the soil total nitrogen content by 39.2% during the budding stage and increased the soil total phosphorus content by 46.2% during the boll-opening stage. In T2 and T3 treatments, the total root length, specific root length, specific surface area, soluble sugar content, and nitrate reductase activity of cotton root were significantly increased, while the root tissue density and aboveground biomass were significantly decreased in gray desert soil. During the cotton budding stage in aeolian sandy soil, the specific root length of cotton were significantly increased by 11.9% and 9.6% under T2 and T3 treatments, respectively. Under T2 and T3 treatments during the cotton boll-opening stage in aeolian sandy soil, the alkaline nitrogen contents in the soil significantly were increased by 51.3% and 97.9%, respectively, while the total root length of cotton were significantly decreased by 26.9% and 21.0%; the specific root length of cotton were significantly decreased by 33.4% and 36.5%. T2 treatment significantly reduced the specific root surface areas by 18.8% and 19.3% during two stages, respectively. T3 treatment significantly increased the average root diameter (65.3%) and aboveground biomass (27.6%) of cotton during the boll-opening stage in aeolian sandy soil. [Conclusion] Partial substitution of chemical fertilizers with organic fertilizers can improve the physical and chemical characteristics of grey desert soil and aeolian sandy soil, increase soil nutrient contents, promote the physiological activity of cotton root, optimize root configuration, and enable cotton root to invest less biomass to obtain higher nutrient absorption benefits, optimize the allocation of biomass, and ultimately alleviate continuous cropping obstacles. In grey desert soil, organic fertilizer replacing 40% chemical fertilizer treatment has the best effect. The effect of partially substituting chemical fertilizers with organic fertilizers in sandy soil varies depending on the proportion of organic fertilizer added and the growth period.

[Objective] This research aims to analyze the resilience level and its influencing factors of China's cotton industrial chain, and to provide reference for the development of cotton industry. [Methods] Based on the resilience theory, a evaluation index system for resilience of cotton industrial chain was constructed from four dimensions of resistance capability, recovery capability, update capability, and government power. And a dynamic evaluation model based on entropy weight-virtual optimal solution technique for order preference by similarity to an ideal solution (TOPSIS) and grey relational analysis was used to measure the resilience level of cotton industrial chain in China from 2007 to 2022. The spatial evolution characteristics of resilience level of cotton industrial chain in China were studied by using the geographic information system (GIS) spatial analysis techniques. Tobit regression model was used to explore the influencing factors of cotton industrial chain resilience. [Results] From 2007 to 2022, the resilience level of China's cotton industrial chain showed a trend of increasing first and then decreasing. In 2007-2016, it was a stable growth period; 2017-2021 was an accelerated growth period; and in 2022, the resilience level decreased, which is a challenging recovery period. From 2007 to 2022, the number of high and higher resilience value area of cotton industrial chain increased, while the number of lower value area decreased. The resilience levels of cotton industrial chain in Xinjiang, Gansu, Shandong, and Hubei were increasing. The levels of opening to the outside world as well as government support showed significant positive impact on the resilience of cotton industrial chain. The impact of scientific and technological innovation level and transportation infrastructure level on the resilience of cotton industrial chain were positive; while the impact of cotton price level was negative. [Conclusion] The resilience level of China's cotton industrial chain is on the rise in general, and the spatial pattern has changed greatly. It is necessary to continue to implement the cotton target price policy, strengthen scientific and technological innovation, and promote infrastructure construction to continuously enhance the resilience of China's cotton industrial chain.

[Objective] This study aims to investigate the regulatory effect of exogenous melatonin (MT) on cotton growth and development under salt stress. [Methods] Guoxinmian 9 was used as the material, and the indoor pot method was adopted with the soil salt content of 0.3%, and after screening out the appropriate MT concentration, four treatments were set: irrigate water + spray water (CK), irrigate salt water + spray water (S), irrigate water + spray MT (MT), and irrigate salt water + spray MT (MS). The plant height, stem diameter, leaf area, relative chlorophyll content (soil and plant analyzer development, SPAD value), biomass per plant, root-shoot ratio, antioxidant enzyme activity, reactive oxygen species content, and osmotic adjustment substance content of cotton under different treatments were studied. And correlation analysis of the above indexes was carried out. [Results] Compared with CK treatment, S treatment significantly reduced plant height, stem diameter, leaf area, SPAD value, aboveground fresh matter mass, underground fresh matter mass, aboveground dry matter mass, and underground dry matter mass, and significantly increased root-shoot ratio of cotton. In the later stage of salt stress treatment, S treatment significantly reduced the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in cotton leaf; significantly increased the contents of hydrogen peroxide, superoxide anion, and malondialdehyde; and significantly decreased the contents of soluble sugar, soluble protein, and proline. Compared with S treatment, foliar spraying 200 μmol·L^-1 MT under salt stress (MS treatment) significantly increased plant height, stem diameter, leaf area, SPAD value, aboveground and underground fresh matter mass, and aboveground dry matter mass per plant; significantly reduced root-shoot ratio; significantly increased SOD, POD, and CAT activities; significantly reduced the contents of hydrogen peroxide, superoxide anion, and malondialdehyde; and significantly increased the contents of soluble sugar, soluble protein, and proline. Aboveground dry matter mass was significantly and positively correlated with plant height, stem diameter, leaf area, SPAD value, aboveground fresh matter mass, underground fresh and dry matter mass, SOD activity, POD activity, CAT activity, soluble sugar content, soluble protein content, and proline content; while was significantly and negatively correlated with superoxide anion content and malondialdehyde content. [Conclusion] Foliar spray 200 μmol·L^-1 MT can effectively alleviate the oxidative stress and osmotic stress of cotton under high salt environment (soil salt content of 0.3%), promote cotton growth, and improve salt tolerance of cotton.

[Objective] This research aims to investigate the effects of planting density and varieties on the morphological structure of vegetative organs and yield of machine-picked cotton in northern Xinjiang. [Methods] Field trials were conducted in 2022 and 2023 at Wulanwusu Agricultural and Meteorological Experiment Station and Manas Agricultural Experiment Station, respectively. Two varieties, CCRI 127 (V1) and Xinshi 518 (V2), were selected, and three planting densities were designed as 11 plants·m^-2 (D1), 22 plants·m^-2 (D2), and 28 plants·m^-2 (D3), respectively. The effects of different treatments on leaf length, petiole length, petiole diameter, internode length, and internode diameter of cotton main stems and fruiting branches as well as yield traits were compared. [Results] In 2022 and 2023, V1 showed the smallest leaf length, petiole length, and internode length of main stems and fruiting branches under D1 and D2 treatments, respectively. In 2022, V2 showed the smallest leaf length, petiole length, petiole diameter, and internode length of main stems and fruiting branches under D3 treatment. In 2023, V2 showed the smallest petiole length and internode diameter of main stems and fruiting branches under D3 treatment. Leaf length and internode length of main stems and fruiting branches showed V1 ≥ V2 under the same density in 2022. Leaf length, internode length, and internode diameter of main stems and fruiting branches of V1 and V2 were not significantly different under the same density in 2023. The lint percentage of V2 was significantly higher than that of V1 under the same density both in 2022 and 2023. Seed cotton yield and lint yield of V1 and V2 in 2022 as well as that of V2 in 2023 increased with the increase of planting densities. Seed cotton yield of V1D3 treatment was highest in 2022, and relatively higher in 2023. V2D3 treatment had the highest lint yield in 2022 and 2023. [Conclusion] The preferred planting density under the conditions of this experiment was 28 plants·m^-2, and the lint yield of Xinshi 518 was higher. The results of this study can provide a support for the improvement of the CottonXL model, and provide a reference for the selection of appropriate varieties and planting densities of machine-picked cotton in the northern Xinjiang.

[Objective] Assessing cotton growth status through chlorophyll content offers a swift, accurate, and extensive monitoring of cotton development, which aids in precision farming. [Methods] To enhance the accuracy of chlorophyll content evaluation in cotton, fractional-order differentiation ranging from 0 to 2(with a step size of 0.2) and wavelet transform within scales from 1 to 10 to process the hyperspectral reflectance data collected from both upland cotton and sea island cotton fields were employed. By analyzing the correlation between different spectral processing techniques and chlorophyll content, sensitive spectral bands were identified. Subsequently, support vector machine regression(SVR) and random forest regression (RFR) models were employed to construct hyperspectral estimation models for cotton chlorophyll content. [Results] (1) In the wavelength range from 325 to 1 075 nm, the spectral reflectance curves of the two cotton species show similar overall trends, with reflectance increasing with the increase in chlorophyll content.(2) Following continuous wavelet transform and fractional-order differentiation, the correlationship between hyperspectral data and chlorophyll content improved for both cotton species. Inversion models revealed that using RFR and wavelet energy coefficient 7 had the best results for upland cotton chlorophyll content estimation, with a coefficient of determination (R²) of 0.931, root mean square error (RMSE) of 0.782, and residual prediction deviation (RPD) of 2.162. Similarly, for sea island cotton, employing RFR and wavelet energy coefficient 6 resulted in the most effective chlorophyll content estimation, with the R² of 0.932, RMSE of 1.198, and RPD of 2.687. [Conclusion] This study provides technical insights for remotely estimating chlorophyll content in cotton plants.

[Objective] This study aims to explore the response of Gossypium hirsutum under artificial seawater and NaCl stresses, and to assess the feasibility of using artificial seawater to simulate salt stress for evaluating salt tolerance of cotton germplasms. [Methods] Utilizing 135 distinct G. hirsutum germplasms as the experimental materials, this study investigated the impact of artificial seawater and NaCl stresses on cotton seed germination and seedling growth. Through the integration of principal component analysis, membership function analysis, and cluster analysis methodologies, the comprehensive evaluation of cotton salt tolerance was conducted. The results of two identification methods were verified by field experiments under natural salt stress. [Results] The consistency of the identification results under the two salt stresses were only 52.38%, and there were great differences in the results. The identification results under artificial seawater stress were significantly and positively correlated with the results of field experiments, with a correlation coefficient of 0.720; while that under NaCl stress were not significantly correlated with the field identification results. Under artificial seawater and NaCl stress treatments, 21.90% and 33.33% of the 105 glandless cotton germplasms were resistant or tolerant to salt stress, respectively. Among them, Lu 17 and Handifen 29 showed strong salt tolerance under the two salt treatments. [Conclusion] Using artificial seawater that simulates the composition of coastal soil can identify the salt tolerance of cotton germplasms more accurately. Glandless cotton generally exhibits poorer salt tolerance, but there are still some germplasms with strong salt tolerance that can be used to breed new salt tolerant glandless cotton cultivars.

[Objective] Cotton is a relatively tolerant crop to cadmium (Cd) stress. It is of great significance to breeding and extending the Cd tolerant cotton cultivars for remediation of Cd contaminated soil. This study aims to analysis the inheritance of cotton tolerance to Cd stress and to map the quantitative trait locus (QTL) related to Cd stress. [Methods] In this study, 188 recombinant inbred lines (RIL) called HM188 derived from an intraspecific hybrid between HS46 and MARCABUCAG8US-1-88 were used to study the phenotypic data of germination rate, germination potential, chlorophyll content, plant height, dry and fresh weight at seedling stage under Cd stress, and the Cd stress coefficient of each material was calculated as well. QTL mapping was conducted for each trait and Cd stress coefficient of HM188 population by using complete interval mapping method. [Results] According to the performance and Cd stress coefficient of each trait under Cd stress, MARCABUCAG8US-1-88 was the Cd tolerant parent, while HS46 was a sensitive one. The Cd tolerance of 188 RIL was basically normal distribution, including 23 strong Cd tolerant lines, 49 Cd tolerant line, 67 medium tolerant lines, and 49 sensitive lines. A total of 28 QTL for Cd stress coefficient was identified, which were distributed on 14 chromosomes with explaining of variation of 1.58%~8.41%. Among them, qRFW-13-1 related to root fresh weight was detected in both environments, which explained variation of 7.66% and 7.71%, respectively. [Conclusion] Cd tolerance in upland cotton is a quantitative trait controlled by multiple genes, which was greatly affected by the environment. However, qRFW-13-1 for Cd tolerance may be a stable QTL, which has some application values in molecular breeding for Cd tolerant cotton.

[Objective] This study aims to investigate the effect of proper postponement of soybean sowing on the productivity of cotton-soybean intercropping system. [Methods] Field experiments were conducted in Linqing City, Shandong Province in 2022 and 2023, and five treatments were set up: cotton monoculture (CM), early-sown soybean monoculture (ESM), late-sown soybean monoculture (LSM), cotton intercropped with early-sown soybean (C||ES), and cotton intercropped with late-sown soybean (C||LS). Various agronomic traits, leaf area index (LAI), canopy photosynthetic rate (CAP), crop yield, harvest index, and land equivalent ratio (LER) were compared among the treatments. [Results] Intercropping is beneficial to reduce the number of rotten bolls per cotton plant at the boll-opening stage. Compared with CM and C||ES treatments, cotton LAI of C||LS at the peak boll-setting stage and boll-opening stage were significantly increased, and the average CAP of cotton under C||LS treatment at the peak squaring stage, peak flowering stage, and peak boll-setting stage were significantly increased. Compared with CM, seed cotton yield of C||LS treatment significantly increased by 11.8%-13.5%, and significantly increased by 21.4%-23.5% in the border row. Compared with C||ES treatment, seed cotton yield of C||LS treatment showed a significant increase of 6.4%-9.4%, with a significant increase of 12.9%-14.8% in the border row. Compared with CM and C||ES treatments, the biological yield of C||LS treatment was increased by 14.6%-18.1% and 8.1%-8.6%, respectively; with an increase of 22.9%-31.3% and 11.9%-21.2% in the border row, respectively. There was no significant difference in harvest index among different treatments. Soybean yield under different treatments was as follows: C||ES > C||LS > ESM > LSM. The biological yield of early sowing soybean was higher than that of late sowing soybean. The soybean harvest index of C||LS treatment was the highest. The LER of C||LS treatment was significantly increased by 4.8% compared with that of C||ES treatment. [Conclusion] Properly delaying the sowing date of soybean can alleviate soybean' competition with cotton in the intercropping system, thereby enhancing the overall productivity of the cotton-soybean intercropping system.

[Objective] This research aims to analysis the function of GhWRKY44 gene under drought stress, and to provide candidate gene resources for drought-resistant breeding in cotton. [Methods] The coding sequence of GhWRKY44 gene was obtained by polymerase chain reaction (PCR) from the cDNA of CQJ-5 (Gossypium hirsutum) leaves. And bioinformatics analysis was performed. The expression pattern of GhWRKY44 gene under the treatment of abscisic acid (ABA) and polyethylene glycol (PEG) 6000 were analyzed by quantitative real-time PCR (qRT-PCR). The function of GhWRKY44 genes under drought stress was investigated by using the virus-induced gene silencing (VIGS) technology. [Results] The protein encoded by GhWRKY44 is a member of class Ⅰa WRKY, and is closely related to GbWRKY44. The expression of GhWRKY44 was induced by PEG 6000 and ABA. Compared with the control cotton plants, GhWRKY44 silenced cotton plants showed more severe leaf wilting, and plant survival rate and leaf chlorophyll content (soil and plant analyzer development, SPAD value) were significantly reduced under drought stress. With 6 h and 7 h of dehydration treatment, the leaf water loss rate of GhWRKY44 silenced cotton plants was significantly higher than that of control plants. [Conclusion] Silencing of GhWRKY44 gene reduced drought tolerance of cotton, and GhWRKY44 is a positive regulator of drought tolerance in cotton.

[Objective] GbTMEM214 transgenic Gossypium hirsutum line, obtained using Agrobacterium-mediated method, was used to clarify the sequence characteristics and detection methods of the T-DNA insertion site, and further promote its biosafety evaluation. [Methods] Based on the genome resequencing technology, the sequencing data was compared with the G. hirsutum standard line TM-1 genome sequence by BLASTn, and specific primers were designed to verify the insertion site by polymerase chain reaction (PCR). [Results] The T-DNA carrying the target gene GbTMEM214 was integrated into the position of 57 019 068-57 019 106 bp on chromosome D13 of G. hirsutum genome, resulting in 37 bp deletion of cotton genome. Combined with the flanking sequence of T-DNA insertion site obtained by PCR amplification, the specific detection method for GbTMEM214 transgenic cotton was established. [Conclusion] The T-DNA insertion site and flanking sequence of GbTMEM214 transgenic cotton was obtained based on genome resequencing technology, which can provide technical reference for biosafety evaluation of the transgenic cotton.

[Objective] This study aims to reveal the effects of different irrigation treatments at the flowering and boll setting stage on the photosynthetic characteristics and yield of cotton, and to provide a reference for the optimization of irrigation system in cotton planting areas of northern Xinjiang. [Methods] A field experiment was conducted in Changji, Xinjiang in 2023, with CCRI 125 as the test variety. Three lower limits of irrigation were set at the flowering and boll setting stage, which were 55% field capacity (T1), 60% field capacity (T2), and 70% field capacity (T3), respectively. The local conventional drip irrigation mode was used as the control (CK). The effects of different treatments on the soil moisture content, photosynthetic characteristics, and yield traits of cotton during the flowering and boll setting stage were analyzed. And the correlation and regression relationships between the photosynthetic index, foliar temperature, and the meteorological factors were also explored. [Results] The soil moisture content of 0-60 cm soil layer of T3 treatment was maintained in a relatively high and stable range (18.5%-21.6%) during the flowering and boll setting period. During the early flowering and boll setting period (11 July), the daily average of net photosynthesis rate of T3 treatment was the highest, showing a daily trend of increasing-decreasing-ascending-decreasing. Correlation analyses showed that net photosynthetic rate and transpiration rate were positively correlated with 0-60 cm soil moisture content, foliar temperature, solar radiation intensity, and ambient temperature. Seed cotton yield and irrigation water use efficiency were the highest under T3 treatment, which were significantly increased by 26.46% and 71.43%, respectively, compared with that of CK. The multi-objective evaluation based on the rank-sum ratio method showed that T3 treatment had the best overall effect. [Conclusion] In the northern Xinjiang where water resources are scarce, the lower and upper limits of irrigation at the flowering and boll setting stage setting at 70% and 90% field capacity, respectively, is a reasonable water-saving and high-yield irrigation mode for cotton fields under the drip irrigation with plastic-film mulching.

[Objective] This research aims to explore the impact of planting pattern and irrigation quota on the growth, yield, and fiber quality of cotton in southern Xinjiang. [Methods] Using Xinluzhong 67 as the experimental material, field trial was conducted in Tumxuk City, Xinjiang in 2023. Two planting patterns were set: (66 cm + 10 cm) wide and narrow row configuration (M1), and 76 cm equal row spacing configuration (M2). Three irrigation quotas were set: 3 600 m³·hm^-2 (W1), 4 500 m³·hm^-2 (W2), and 5 400 m³·hm^-2 (W3). The differences in soil moisture content, cotton plant height, stem diameter, leaf area index, photosynthetic performance, yield, irrigation water use efficiency, and fiber quality under different treatments were compared. Additionally, the entropy weight technique for order preference by similarity to ideal solution (TOPSIS) was applied for a comprehensive evaluation to identify the optimal treatment. [Results] All treatments showed the largest increase in average soil moisture content in 0-30 cm soil layer after irrigation during the flowering and boll-setting stage (12.18-15.13 percentage point), followed by 30-60 cm soil layer. Under the same irrigation quota, the average soil moisture content in 0-30 cm soil layer after irrigation of M2 treatment was higher than that of M1 treatment. Under the same irrigation quota, plant height, stem diameter, and leaf area index under M2 treatment were higher than those under M1 treatment. Under the same planting pattern, plant height, stem diameter, and leaf area index of cotton all increased with the increasing of irrigation quota. During the flowering and boll-setting stage, the net photosynthetic rate and water use efficiency of leaf under M2W2 treatment were significantly higher than other treatments. The seed cotton yield of M2W2 treatment was the highest, which was significantly increased by 3.26%-17.70% compared with other treatments, and its irrigation water use efficiency was significantly higher than that of M1W2, M1W3, and M2W3 treatments. M2W1 treatment had the highest irrigation water use efficiency. The cotton fiber of M2W2 treatment showed the largest uniformity index, the upper half mean length and breaking elongation were also higher. The evaluation results of entropy weight TOPSIS method indicated that M2W2 treatment had the optimal overall performance. [Conclusion] Adopting the planting pattern of 76 cm equal row spacing with an irrigation quota of 4 500 m³·hm^-2 can effectively promote the growth and development of cotton, and improve the seed cotton yield and fiber quality in southern Xinjiang.

[Objective] This study aims to investigate the dynamic changes of flavonoids in cotton leaves at different growth and development periods. [Methods] Cotton leaves of sGK156 at seedling stage, flourishing flowering stage, and boll opening stage were used as study materials, and the differential metabolites were analysed and flavonoids abundance was detected by ultra-high-performance liquid chromatography-tandem mass spectrometry. [Results] Differential compounds of cotton leaves at three different periods were mainly enriched in the biosynthesis of flavone and flavonol, and the biosynthesis of flavonoids. Compared with those at the flourishing flowering stage and boll opening stage, kaempferol-3-O-arabinopyranoside and naringenin in cotton leaves were significantly higher at the seedling stage, and the contents of 16 flavonoids such as astragalin, tiliroside, and quercetin in cotton leaves at flourishing flowering stage were significantly higher than those at seedling stage and boll opening stage, and the contents of 5 compounds of epicatechin, kaempferol-3-O-rutinoside, kaempferol-3-O-vicianoside, procyanidin B2, and fraxin were significantly higher at the boll opening stage compared with seedling stage and flourishing flowering stage. [Conclusion] This study further analyses the dynamic changes of flavonoid secondary metabolites in cotton leaves during different growth periods, and discover the dominantly expressed flavonoid metabolites in cotton leaves during different growth periods. It provides a theoretical basis for the further study and utilization of flavonoid metabolites in cotton leaves and the selection and breeding of excellent cotton varieties.

[Objective] This study aims to investigate the effects of nitrogen (N) fertilizer top dressing frequency under drip irrigation on soil N content and cotton yield in southern Xinjiang, and to provide references for the rational N application. [Methods] Field experiments were conducted in Xayar County, Aksu Prefecture, Xinjiang, from 2021 to 2022. With the same total amount of pure N applied (300 kg·hm^-2, 20% basal application, and 80% top dressing with water), four treatments of N fertilizer top dressing frequency were set up (4, 6, 8, and 10; recorded as N4, N6, N8, and N10, respectively). The effects of different treatments on soil total N content and alkali-hydrolyzable N content in the cotton field, cotton dry matter mass and N content, cotton yield, and N partial productivity were analyzed. [Results] The effects of different treatments on soil N content in cotton field changed with cotton growth process. The soil total N and alkali-hydrolyzable N supply under N10 were relatively sufficient at the seedling stage, peak boll-setting stage, and boll opening stage, but was unfavorable to N supply at the squaring stage and peak flowering stage. Whereas soil total N and alkali-hydrolyzable N content were maintained at a higher level during the whole growth stage of cotton under N8. Also under N8, the maximum accumulation rate of dry matter and nitrogen in cotton plants, vegetative organs, and reproductive organs were the highest in 2022; the maximum accumulation rate of N in reproductive organs was the highest in 2021; the dry matter mass and N content of cotton plants, vegetative organs, and reproductive organs were relatively higher in 2021 and 2022. With the increase of N fertilizer top dressing frequency, seed cotton yield and N partial productivity increased firstly and then decreased, and all the highest ones were under N8. Compared with other treatments, seed cotton yield under N8 increased by 3.3%-39.2% and 13.3%-72.8% in 2021 and 2022, respectively; N partial productivity showed the same change range. [Conclusion] Under the water and fertilizer integration mode in the cotton field in southern Xinjiang, top dressing N fertilizer applied with irrigation for 8 times is beneficial to ensure the N supply of the cotton field, and to promote the accumulation of the dry matter and nitrogen in cotton, thus improving cotton yield and N partial productivity.

[Objective] This study aims to systematically identify the chemical constituents of cotton stalk, laying the basis for in-depth exploitation and utilization of cotton stalk. [Methods] The ultra-high-performance liquid chromatography-quadrupole-electrostatic field orbitrap high resolution mass spectrometry (UHPLC-Q-Exactive orbitrap MS) was performed with a Thermo Scientific Hypersil GOLD^TM aQ (100 mm × 2.1 mm, 1.9 μm) chromatographic column using gradient elution consist of 0.1% formic acid (A)-acetonitrile (B) as the mobile phase at a flow rate of 0.3 mL·min^-1, while the column temperature was set at 40 ℃, and the injection volume was 2 μL. The MS used electrospray ionization(ESI) source to gain the high-resolution mass data in positive or negative models by full MS scan with data dependence MS²(full MS/dd-MS²) involved in parallel reaction monitoring (PRM). [Results] A total of 102 components from cotton stalk were identified, including 13 flavonoids, 48 organic acids, 8 nucleotides, 10 terpenoids, 8 amino acids, 3 coumarins, 2 alkaloids, and 10 other compounds. Among them, 92 were found in cotton stalk for the first time. [Conclusion] The method based on UHPLC-Q-Exactive orbitrap MS combined with PRM was established, which is easy to operation, with high sensitivity, good specificity and rapid analysis. By this method, 102 compounds were identified in cotton stalks, and 92 compounds were identified for the first time, laying the foundation for the further development and utilization of cotton stalk. It provides reference for the in-depth exploitation and utilization of cotton stalk.

[Objective] This paper aims to solve the problem of accurate recognition and localization of cotton with different postures and grades by cotton picker under the requirement of high-quality cotton picking. A cotton detection method YOLOX-Cotton based on the improved YOLOX is proposed. [Methods] YOLOX-Cotton uses YOLOX as the main framework, including a recognition module and a localization module, and incorporates coordinate attention (CA) module and SIoU loss function, and takes various posture and grade cotton pictures as data sets to train and test. [Results] The detection module of YOLOX-Cotton was capable of detecting cotton with different postures and grades, and the model precision, recall and average precision reached 92.9%, 86.8% and 92.4%, which were improved by 5.2, 5.5 and 6.1 percentage points, compared with the original YOLOX, respectively. The localization module of this model was capable of accurately obtaining the location of the cotton, the measurements were kept within the threshold range of the validated results of the field trial, and the standard deviation of all samples was less than 0.01. [Conclusion] The experiment proves that the YOLOX-Cotton can effectively solve the problem of cotton detection and localization by cotton picker under the requirement of high-quality cotton picking, and provides strong technical support for the realization of high-quality cotton picking.