[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 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 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 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 clarify the sequence structure of cytochrome P450 (CYP450) gene and glutathione S-transferase (GST) gene of Thrips tabaci, and the expression of these genes at the different growth and development stages of T. tabaci and emamectin benzoate stress. [Methods] Based on the transcriptome data of different growth and development stages of T. tabaci, CYP450 genes and GST genes were mined, specific primers were designed, and polymerase chain reaction (PCR) was used to amplify the cDNA of these genes. Bioinformatics software was used to predict the structural characteristics of CYP450 and GST proteins. The indoor toxicity of emamectin benzoate to adult T. tabaci was determined by leaf dipping method. Quantitative real time PCR (qRT-PCR) was used to analyze the expression patterns of CYP450 and GST genes at the different development stages of T. tabaci and under the stress of emamectin benzoate. [Results] Three CYP450 genes (CYP4C101, CYP4C102, CYP6K1) and two GST genes (GST1, GSTX1) were cloned. The results of physicochemical analysis showed that CYP4C101, CYP4C102, CYP6K1, GST1, and GSTX1 were composed of 507, 528, 513, 215 and 207 amino acid residues, respectively, all of which were hydrophilic proteins. Phylogenetic analysis showed that CYP4C101 had the highest homology with CYP4C1 of Frankliniella fusca. CYP4C102, CYP6K1 and GST1 of T. tabaci had the highest relationships with the homologous proteins from F. occidentalis and F. fusca. GSTX1 had the highest homology with F. occidentalis. Domain prediction showed that CYP4C101, CYP4C102 and CYP6K1 had conserved domains of CYP450, and GST1 and GSTX1 had conserved domains of GST. The results of indoor toxicity test showed that the LC₂₀ value of emamectin benzoate was 4.01 mg·L^-1 at 48 h. The results of qRT-PCR showed that CYP4C101, CYP4C102, CYP6K1, GST1, and GSTX1 genes were expressed at all development stages, and the expression levels were the highest on the 9^th day of adult emergence. The expression levels of the above-mentioned genes were significantly up-regulated under the stress of emamectin benzoate LC₂₀ for 24 h. Among them, CYP4C101, CYP4C102, and CYP6K1 were significantly up-regulated to 4.43, 22.91 and 8.48 times, respectively, and GST1 and GSTX1 were significantly up-regulated to 9.06 and 5.26 times, respectively. At 48 h after emamectin benzoate LC₂₀ treatment, the expression levels of CYP4C102 and CYP6K1 were significantly up-regulated by 3.84 and 1.43 times, respectively. The expression levels of CYP4C101, GSTX1, and GST1 were up-regulated but did not reach a significant difference level. [Conclusion] Three CYP450 genes and two GST genes of T. tabaci were cloned, and the expression levels of the five genes were the highest on the 9th day of adult emergence. Under the stress of emamectin benzoate LC₂₀, although these five detoxification genes were induced to express at different times, they may be involved in the response of T. tabaci to emamectin benzoate, providing clues for subsequent functional studies of CYP450 and GST genes.

[Objective] This research aims to measure the digital development level of cotton field in Xinjiang, analyze the obstacle factors and the main issues of the digital transformation, and propose corresponding countermeasures, so as to provide reference for promoting the modernization development of cotton industry in Xinjiang. [Methods] The evaluation index system was constructed from four dimensions: digital foundation, digital support, digital application, and digital efficiency. Analytic hierarchy process-entropy combination assigning method and the obstacle factor analysis method were used to analyze the digital development level and main obstacles of cotton field in Xinjiang from 2012 to 2021. [Results] The digital development level of cotton field in Xinjiang is increasing year by year. The composite score was raised from 1.68 in 2012 to 28.42 in 2021. The main obstacles to the digital development of Xinjiang cotton field have changed from the digital foundation, digital support, and digital applications in 2012 to digital applications and digital efficiency in 2021. Xinjiang cotton field has shortcomings in digital technology application, capital investment, large-scale development, technical personnel and so on. [Conclusion] The digital development of cotton field in Xinjiang has achieved some results, but there are still some problems. By strengthening the research and promotion of digital technology, promoting the scale and organization of cotton field, increasing policy support, and cultivating composite technical talents, it is expected to promote the digital transformation and upgrading of cotton field in Xinjiang.

[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 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 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 aimed to clarify the effect of N-life Ⅱ (the main active ingredient is nitrapyrin) on soil nutrient contents and soil nitrogen (N) cycle-related enzyme activities under different application levels of N, so as to provide a basis for the application of N-life Ⅱ in cotton production. [Methods] Field experiments were carried out at Sanya, Hainan province in 2021 and 2022 with Zheda 12 as the experimental material. The field experiment was designed with two factors split-pot. The main plot was N-life Ⅱ application level: 22.5 kg and 0 kg (control) per hectare, respectively; the secondary plot was pure N application level: 285.0 kg (conventional level), 256.5 kg (10% N reduction), 228.0 kg (20% N reduction), and 199.5 kg (30% N reduction, 2022 only) per hectare, respectively. N, phosphorus and potassium contents as well as urease, ammonia monooxygenase (AMO), hydroxylamine oxidoreductase (HAO), nitrite oxidoreductase (NXR), nitrate reductase (NR), and nitrite reductase (NiR) activities in soil were analyzed at the seedling stage, flowering and boll setting stage, and boll opening stage of cotton under different treatments. [Results] Compared with the respective control treatments at the same N application level, soil ammoniacal N content increased at the flowering and boll setting stage and boll opening stage under the N-life Ⅱ treatment; soil nitrate N content decreased at the seedling stage and flowering and boll setting stage, and increased at the boll opening stage; and there were no significant differences in the contents of soil total N, P₂O₅ and K₂O at the seedling stage, flowering and boll setting stage, and boll opening stage. Compared with the mean values of all control treatments, the average soil total N content under N-life Ⅱ treatments was significantly increased by 6.10% to 6.63% at the boll opening stage; the average soil P₂O₅ and K₂O contents under N-life Ⅱ treatments were significantly reduced during the flowering and boll setting stage and boll opening stage. Application of N-life Ⅱ reduced the activities of soil urease, AMO, NR, and NiR at the seedling stage and flowering and boll setting stage; reduced soil NXR activity at the seedling stage; enhanced soil urease activity at the boll opening stage; and enhanced soil NiR activity at the boll opening stage under the normal N application level; while had no significant effect on soil HAO activity at different growth stages. [Conclusion] Under different application levels of N, N-life Ⅱ reduced soil nitrate N content at the seedling stage and flowering and boll setting stage, and increased soil ammoniacal N content at the flowering and boll setting stage and boll opening stage by inhibiting the activities of urease, AMO, NXR, NR, and NiR in soil.

[Objective] Low temperature is one of the main agrometeorological disasters during the cotton seedling period in Aksu Prefecture of Xinjiang, which seriously limits the stability and safety of cotton production. Clarifying the risk areas of cotton low temperature disaster during cotton seedling period in Aksu Prefecture can effectively improve the defense ability of this region to cope with low temperature. [Methods] Based on the meteorological data of Aksu Prefecture from 1961 to 2020, the changing trends of daily maximum temperature, daily minimum temperature, daily average temperature, and the changing frequency of low temperature disasters (cold wave and late frost injury) during the seedling period of cotton were analyzed by using the climatic tendency rate. The time distribution characteristics of cold wave and late frost injury in April to May were also analyzed. A comprehensive risk assessment model for low temperature disaster was established, and the risk regionalization of low temperature disaster during cotton seedling stage was carried out by analyzing the hazard index of low temperature disaster-inducing factors, and combining the exposure index of the hazard-bearing body, and local the disaster prevention and mitigation capacity. [Results] From 1961 to 2020, the daily minimum temperature, daily maximum temperature, and daily average temperature during the cotton seedling period in Aksu Prefecture showed a significant increasing trend, and the frequency of cold wave and late frost injury showed a decreasing trend. The incidence of cold wave and late frost injury in Aksu Prefecture is below 20% after 10 April and 12 April, respectively. The risk level of spring low temperature disaster-causing factors in Aksu Prefecture showed the spatial distribution characteristics of “high in the north and low in the south, high in the west and low in the east”. The results of comprehensive risk regionalization indicated that the central and east-central areas of Aksu Prefecture, which including Aral City, the central part of Aksu City, the north-eastern part of Awati County, the eastern edge of Kalpin County, the eastern part of Xinhe County, the south-western and central part of Kuqa City, the northern part of Xayar County, and the south-eastern part of Wensu County are the highest or higher level risk zones of low temperature disaster. [Conclusion] Although the spring temperature increased, and the frequency of cold wave and late frost injury decreased in Aksu Prefecture, the risk of low temperature disaster is still high in the central and east-central cotton growing areas in Aksu Prefecture, and targeted measures are needed to be taken to mitigate the impact of low temperature disasters on cotton production.

[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] The purpose of this study was to trace the breeding process of Hai 7124, and clarify the characteristics of strains thorough analyzing the evolution of several traits, so as to provide reference for further exploring the value of Hai 7124 in cotton genetic breeding and resource utilization. [Methods] By consulting the historical research archives preserved by Institute of Industrial Crops, Jiangsu Academy of Agricultural Sciences, the growth period, boll setting capacity, yield, fiber quality, disease resistance, plant architecture and other informations of the original materials and the selected breeding materials involved in the selection process of Hai 7124 were analyzed. [Results] The breeding of Hai 7124 began in 1959 with the introduction of the original material named Menoufi from Egypt, and went through ten generations of systematic selection. The key individual plant 65-3049-6 was obtained in 1965, and the selected line numbered 7124 with excellent characteristics was obtained in 1974, which named Hai 7124. Systematic selection not only promoted the early maturity of Hai 7124, but also preserved the excellent characteristics of the original material Menoufi and the related breeding materials, including good fiber quality, high yield, and strong resistance to Verticillium wilt. Additionally, it contributed to the formation of compact plant architecture. [Conclusion] Hai 7124 was derived from the original material Menoufi. The systematic selection promoted early maturity, and retained excellent traits, such as good fiber quality, high yield, and resistance to Verticillium wilt.

[Objective] The objective of this study is to study the effects of exogenous application of proline on carbon source utilization by soil microorganisms in the cotton rhizosphere and soil enzyme activities, and deeply understand the ecological mechanism of proline in disease prevention and cotton growth promotion. [Methods] In this study, the application of different proline concentrations (0, 50, 100, 200 and 400 mmol·L^-1) were set, with a cotton Verticillium wilt-susceptible variety Ejing 1 as the experimental material, and the Biolog-ECO plate method was used to evaluate the functional diversity and carbon source utilization of rhizosphere soil microbial communities under different treatments. Principal component analysis was used to compare the carbon source utilization characteristics of rhizosphere soil microorganisms under different treatments. The activities of neutral phosphatase (NP), arylsulfatase (ASF), urease (UE), and β-glucosidase (β-GC) in cotton rhizosphere soil of different treatments were determined, respectively. Redundancy analysis was used to analyze the correlation between soil enzyme activities and the utilization ability of soil microorganisms for different types of carbon sources. [Results] The McIntosh index of soil microorganisms treated with 400 mmol·L^-1 proline increased significantly, while there were no significant differences in the Simpson index, Shannon-Wiener index, Richness index, and Pielou index of soil microorganisms treated with proline compared with control. The soil microbial metabolic activities treated with 50-200 mmol·L^-1 proline were all lower than that of the blank control after incubating for 6 to 20 days, while the soil microbial metabolic activity treated with 400 mmol·L^-1 proline was significantly higher than that of the blank control. Soil microorganisms treated with proline have higher utilization ability for amino acids, carboxylic acids, and carbohydrates. The utilization ability of soil microorganisms treated with 50-400 mmol·L^-1 proline was significantly enhanced for L-phenylalanine, D-galactonolactone, β-methyl-D-glucoside, and glycogen; while the utilization ability for L-arginine, D-galacturonic acid, D-xylose, and i-erythritol was significantly reduced. Compared with the blank control, proline treatments significantly reduced the activities of soil β-GC and UE, and had no significant effect on the activity of NP. The activity of ASF showed a trend of first decreasing and then increasing with the increase of proline concentration. Redundancy analysis shows that UE activity was positively correlated with the utilization ability of soil microorganisms for L-arginine, D-galacturonic acid, γ-hydroxybutyric acid, D-xylose, and i-erythritol; β-GC activity was positively correlated with the utilization ability of soil microorganisms for L-arginine, pyruvic acid methyl ester, D-xylose, and i-erythritol; NP activity was positively correlated with the utilization ability of soil microorganisms for L-asparagine, D-galacturonic acid, γ-hydroxybutyric acid, glycogen, and β-methyl-D-glucoside; ASF activity was positively correlated with the utilization ability of soil microorganisms for L-phenylalanine, L-serine, L-threonine, glycyl-L-glutamic acid, D-glucosaminic acid, D-galactonolactone, itaconic acid, and D-mannitol, respectively. With carbohydrates as carbon source, the activities of β-GC and UE are negatively correlated with the utilization ability of soil microorganisms for glycogen. [Conclusion] The proline treatments can change the soil microbial metabolic activities, leading to a significant decrease in the activities of soil β-GC and UE. With carbohydrates as carbon source, the activities of β-GC and UE are positively correlated with the utilization ability of soil microorganisms for D-xylose and i-erythritol, but negatively correlated with the utilization ability of soil microorganisms for glycogen.

[Objective] The occurrence of Amrasca biguttula in the cotton field of Hunan Province is increasingly growing. The purpose of this study was to analyze the genetic diversity and genetic differentiation of A. biguttula in Hunan Province. [Methods] In 2023, 14 geographical population samples of A. biguttula were collected in Hunan Province. Based on the mitochondrial DNA (mtDNA) cytochrome c oxidase subunit Ⅰ (COⅠ) gene sequences obtained by polymerase chain reaction (PCR), the genetic diversity, genetic differentiation, population dynamics, and systematic evolution of the 14 geographical populations of A. biguttula in Hunan Province were analyzed using MEGA 7.0, DnaSP 6.1, Arlequin 3.5, Network 10.2, and other softwares. [Results] The mtDNA COⅠ sequences of 568 bp were obtained from 140 individuals by PCR. A total of 14 haplotypes (Hap1-Hap14) were detected, among which Hap1 was shared by all populations. Hapl had a frequency of 87.86%, and was the original haplotype. The haplotype diversity index of the whole A. biguttula community was 0.226 95, the nucleotide diversity was 0.000 52, and the average number of nucleotide difference was 0.296 25. The genetic distance between haplotypes ranged 0.001 76 to 0.007 09. The whole A. biguttula community had a low degree of genetic differentiation (the genetic differentiation coefficient is 0.016 84), and active gene exchange (the gene flow is 29.19). Molecular variance analysis (AMOVA) results indicated that genetic variation mainly originated within the population. The Tajima's D, Fu and Li's D, and Fu and Li's F neutral tests for the whole A. biguttula community were significantly negative, suggesting that the A. biguttula population in Hunan Province is undergoing expansion. [Conclusion] The geographical population of A. biguttula in Hunan Province showed low genetic diversity, active gene exchange, and low genetic differentiation; and the total population is experiencing obvious expansion. Active monitoring and control measures should be taken to ensure the healthy development of cotton industry in Hunan Province.

[Objective] This study aims to explore the impact of diverse mulching techniques and irrigation quota on each application on cotton production. [Methods] Field experiments were conducted in Aral City, Xinjiang from 2017 to 2019. For the experiments under drip irrigation with plastic-film mulching in 2017 and 2018, Xinluzhong 46 was used as the test material, and three irrigation quotas on each application of 24 mm (M1), 30 mm (M2), and 36 mm (M3) were set. For the experiments under drip irrigation without plastic-film mulching in 2018 and 2019, Zhongmian 619 was used as the test material, and three irrigation quotas on each application of 36 mm (W1), 45 mm (W2), and 54 mm (W3) were set. The effects of different treatments on the soil temperature and water content in 10 cm, 20 cm and 40 cm soil layers, seed cotton yield, and irrigation water use efficiency were analyzed. [Results] The soil water content in 10 cm, 20 cm, and 40 cm soil layers of cotton fields, and seed cotton yield under the two mulching modes showed an increasing trend with the increase of irrigation quota on each application. Notably, the seed cotton yield of M2 and M3 treatments were significantly increased by 8.82%-11.47% and 14.24%-18.96% compared with M1 treatment, respectively. The seed cotton yield of W2 and W3 treatments were increased significantly by 15.18%-22.61% and 32.53%-46.29%, respectively, in comparison to W1 treatment. Both soil temperature and irrigation water use efficiency showed a declining trend with the increasing of irrigation quota on each application. The irrigation water use efficiency of M2 and M3 treatments were significantly declined by 10.82%-12.94% and 20.70%-23.84%, respectively, in comparison to M1 treatment. The irrigation water utilization efficiency of W2 and W3 treatments also showed a reduction, ranging from 1.91%-7.85% and 2.47%-11.65%, respectively, in comparison to W1 treatment. When the irrigation quota on each application were the same in 2018, the soil water content, soil temperature in 0-40 cm soil layer, seed cotton yield, and irrigation water use efficiency of M3 treatment were higher than that of W1 treatment. The comprehensive evaluation based on the technique for order preference by similarity to ideal solution (TOPSIS) indicated that superior outcomes could be obtained by aligning 30 mm irrigation quota on each application with the drip irrigation with plastic-film mulching treatment, and 54 mm irrigation quota on each application with the drip irrigation without plastic-film mulching treatment. [Conclusion] An increase in irrigation quota on each application can serve to offset the reduction in seed cotton yield resulting from the filmless planting mode to a certain extent, albeit at the cost of reduced irrigation water use efficiency. The findings of this study may provide reference for the promotion of drip irrigation without plastic-film mulching cotton planting technology in the local area.

[Objective] The aim of this study is to analyze the structural and molecular characteristics of Propylea japonica tyrosine decarboxylase (TDC) genes, and their expression pattern and to explore their regulatory role as a key octopamine synthetase gene in the reproductive development of ladybird beetle. [Methods] Four PjTDC genes and their basic structural characteristics were identified by bioinformatics software. PjTDC1 gene was cloned by polymerase chain reaction. The expression pattern of PjTDC1 gene in different tissues and at different developmental stages were investigated by quantitative real-time polymerase chain reaction. And the function of PjTDC1 gene in P. japonica were studied by RNA interference techniques. [Results] There were four TDC genes in the P. japonica, which were named PjTDC1-4. All the TDC proteins of P. japonica have PLN02880 domain, and PjTDC1 gene has an open reading frame of 1 728 bp, encoding 575 amino acid residues. PjTDC1 protein has the highest homology with the TDC protein of Cylas formicarius. PjTDC1 gene was expressed in P. japonica at different developmental stages, with the highest expression level in the 1^st instar larvae but lower expression level in the egg stage larvae, the 4^th instar larvae, and 7-day-old female adults. Generally speaking, the expression level of PjTDC1 decreased gradually at larval stages and in the adults after eclosion for 1 to 7 days. PjTDC1 gene is also expressed in different tissues, but it is mainly expressed in the ovaries, dorsal cuticula and head of the 5-day-old female adults. The results of RNA interference experiment showed that silencing of PjTDC1 gene inhibited the deposition of vitellogenin in the oocytes of P. japonica. In addition, on the 1^st and 3^rd day after injection of double strand RNA, the width of primary oocytes in the treatment group was significantly 10.03% and 18.60% lower than that in the control group. These results suggest that PjTDC1, as a key gene for octopamine synthesis, also plays an important regulatory role in the reproductive development of P. japonica. [Conclusion] In this study, the basic structural features of PjTDC genes and the spatial and temporal expression pattern of PjTDC1 at different developmental stages and in different tissues of P. japonica were studied, and its positive regulatory role in the process of vitellogenin deposits in the oocytes of P. japonica were clarified, which will provide theoretical basis for further solving the problem of large-scale artificial propagation of P. japonica.

[Objective] This study aims to investigate the potential of cotton carbon credits under the CCER (Chinese Certified Emission Reduction) mechanism, quantitatively evaluate the greenhouse gas reduction potential of cotton production that can participate in the CCER mechanism, predict the economic value it can generate, and explore the possibility of additionality certification for cotton carbon credits based on the CCER mechanism. [Methods] First, a counterfactual analysis framework was constructed through scenario division. Based on the existing mature life cycle assessment boundaries of cotton, components meeting the requirements of the CCER mechanism were identified. The development potential, economic value, and future trends of cotton carbon credit in China's three main cotton regions were estimated and predicted. Furthermore, the additionality of cotton carbon credit was demonstrated using the general proof methods required by the CCER mechanism. [Results] The cotton carbon credit in China's three main cotton regions exhibits significant development potential and economic value. Under the best-line scenario, the annual average carbon credit potential and economic value from 2014 to 2023 were 7.932 4 million tons of CO₂ equivalence and 729 million CNY, respectively, with an upward trend. Under the better-line scenario, the respective figures were 2.412 3 million tons of CO₂ equivalence and 222 million CNY. The Northwest Inland Cotton Region is the primary area for cotton carbon credit development, accounting for over 90% and continuing to increase. Promoting and adopting low-carbon agricultural technologies can help cotton carbon credits pass the additionality certification based on the CCER mechanism. The better-line scenario's technological choices provide a more pragmatic approach. [Conclusion] The three main cotton-growing regions in China, especially the Northwest Inland Cotton Region, have great potential for carbon credit development. Considering the practical context of "increased production equating to increased income", efforts should focus on leveraging the scale advantages of the Northwest Inland Cotton Region and exploring collaborative cooperation models between the upstream and downstream ends of the industry chain to promote the practical development of cotton carbon credit.

[Objective] This study aims to investigate the development characteristics of cotton carpel, the differentially expressed genes and plant hormone content among different carpel numbers, and the relationship between carpel number and cotton boll development. [Methods] Cotton plants with three carpels (C3), four carpels (C4), and five carpels (C5) were used as the research subjects. The development process of cotton carpel was observed, and the number of carpel in the offspring of different combinations was counted. Transcriptome sequencing and plant hormone content measurement of the carpels were performed at 5 days and 10 days after flower bud development, and on the day of flowering. Phenotype of cotton boll was measured at different developmental stages. [Results] When the flower bud length was 2-3 mm, the development of carpel primordia started; and when the flower bud developed to 4-5 mm, the carpel fused to form fully fused carpel. The development of carpel primordia preceded of pistil organ. The average number of carpel in F₁ from different crosses between C3, C4, and C5 parents was between the two parents. The differentially expressed genes of C3, C4, and C5 are mainly enriched in biological processes. During floral bud development at 5 days and 10 days, and on the day of flowering, the expression levels of key genes related to carpel development in the enrichment pathway, including AP1, AGL6, WUS, MYB21, and ARF6, in C5 were higher than that in C4, and significantly higher than that in C3. At 5 days and 10 days of floral bud development, jasmonic acid (JA) content in C5 was significantly higher than that in C3 and C4, while indole acetic acid (IAA) content was significantly lower than that in C3 and C4; abscisic acid content in C4 was significantly lower than that in C3 and C5. At 20 days, 35 days, and 60 days after flowering, the cotton boll diameter, fresh weight of cotton boll, thickness of cotton boll petals, and fresh weight of fiber and ovule in C5 were significantly higher than that in C3 and C4. [Conclusion] The average number of carpel in the offspring from different crosses between the parents with 3, 4, and 5 carpels was between the two parents. Several carpel development-related genes showed higher expression level in C5. Before flowering, C5 has the highest content of JA and the lowest content of IAA. Increasing carpel number is conducive to increase the boll diameter, boll fresh weight, and fresh weight of fiber and ovule.