[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 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 aimed to screen the single-guide RNA (sgRNA) for gene editing of GhOMT1 (encoding flavonoid 3-O-methyltransferase) and GhPGF (related to gland formation) in cotton, laying the foundation for rapid detection of mutant plants. [Methods] Based on the Cas9-overexpressing cotton Jin668, sgRNAs targeting GhOMT1and GhPGF genes were designed. The editing efficiency and specificity of the sgRNAs were detected by using the cotton leaf crumple virus (CLCrV) vector-mediated gene editing system and high-throughput tracking of mutations (Hi-TOM) technology. [Results] GhOMT1-sgRNA2 and GhPGF-sgRNA induced mutations at the target sites of GhOMT1 and GhPGF, respectively. Hi-TOM sequencing revealed that 12 out of 15 cotton plants transformed with GhOMT1-sgRNA2 exhibited mutations, with a mutation efficiency of 80%. The editing efficiency in single plants ranged from 7.90% to 43.72% for the A subgenome and from 9.60% to 56.32% for the D subgenome. The mutation efficiency of GhPGF-sgRNA was 80%, with an editing efficiency ranging from 10.23% to 30.27%. No off-target effects were observed at the three potential off-target sites of GhOMT1-sgRNA2, and GhPGF-sgRNA had no potential off-target sites in the coding regions of the genome, indicating the high specificity of these sgRNAs. [Conclusion] One sgRNA targeting GhOMT1 and one sgRNA targeting GhPGF were screened using the CLCrV-mediated gene editing 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] Accurate identification of cotton species is of great significance for breeding, cultivation management, and pest control. However, the traditional manual identification method is subjective and inefficient. Therefore, this study aims to develop a rapid classification model based on red, green, and blue(RGB) image and random forest (RF) algorithm to realize automatic recognition of cotton species. [Methods] In this study, Gossypium herbaceum, G. arboreum, G. barbadense, and G. hirsutum lines were planted to collect the RGB images of cotton leaves at the squaring stage and the flowering and boll-setting stages, then the color and morphological feature parameters were extracted. Based on the extracted features, three RF models were constructed: one using only leaf features at the squaring stage, another using only leaf features at the flowering and boll-setting stages, and a comprehensive model combined features from both stages. The classification performance of each model was evaluated, and the key features affecting cotton species were identified through feature importance analysis. To assess the superiority of the RF model, the classification effect of the support vector machine(SVM) and K nearest neighbor (KNN) algorithm was conducted for comparison. [Results] The classification model combining the leaf features of the squaring stage and the flowering and boll-setting stages had the highest accuracy, with an overall accuracy of 97.71% and a Kappa coefficient of 0.95, which was superior to the model based only on leaf features from a single growth stage. Feature importance analysis showed that leaf area and roundness played an important role in cotton species recognition. Additionally, the RF model demonstrated better classification performance than SVM and KNN, exhibiting higher stability and accuracy. [Conclusion] The cotton species identification method based on RGB images and the RF algorithm proposed in this study does not require complex image pre-processing and can provide new insights and technical support for crop precision management and the application of machine learning algorithms in agriculture.

[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] 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 explore the effects of applying different amounts of 1,1-dimethyl piperidinium chloride (DPC) through drip irrigation on cotton plant architecture characteristics and yield traits under dry-sowing and wet-emergence planting mode, and to screen the optimal amount of DPC, so as to promote the simplified chemical manipulation of cotton. [Methods] Field experiments were conducted in Shawan City, Xinjiang, from April 2023 to October 2024. The control treatment (CK) was established with foliar application of 315 g·hm^-2 DPC. Four treatments were set up with different drip application rates of DPC: 315 g·hm^-2 (D1), 630 g·hm^-2 (D2), 1 260 g·hm^-2 (D3), and 1 890 g·hm^-2 (D4). The effects of drip-applied DPC on cotton plant height, plant width, stem diameter, and other plant architecture characteristics, as well as leaf area index (LAI), and yield traits were investigated. [Results] In 2023 and 2024, cotton plant height, internode length of main stem, cotyledon node height, plant width, fruiting branch length, number of fruiting branches per plant, height of the first fruiting branch node, and LAI all decreased with the increasing amount of DPC through drip irrigation. There were no significant differences between D2 and CK treatment in plant height, cotyledon node height, plant width, vegetative shoot length, stem diameter, fruiting branch number per plant, first fruiting branch node and its height, plant height-width ratio, fruiting node number-fruiting branch number ratio, and LAI (except for peak boll-setting stage in 2023). There were no significant difference in harvest density and lint percentage among different treatments. Compared with CK treatment, the boll weight of D1-D4 treatment and the boll number per plant of D1 and D2 treatment were no significant difference, and the boll number per plant of D3 and D4 treatment were significantly reduced. The seed cotton yield of D2 treatment showed no significant difference with CK, and it was higher than that of D1 treatment, and significantly increased by 19.7% to 20.0% and 27.1% to 49.6%, respectively compared with D3 and D4 treatments. [Conclusion] The application of 630 g·hm^-2 DPC through drip irrigation under the dry-sowing and wet-emergence planting mode in cotton fields of northern Xinjiang can effectively regulate the plant architecture of cotton, ensuring high cotton yield.

[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] With the adjustment of planting structure and the change of planting area of cotton in China, the main diseases and pests are constantly evolving, especially in the case of the sharp fluctuation of cotton planting area in the Yellow River Basin. Clarifying the evolution characteristics of diseases and pests in this area can provide reference for scientific control. [Methods] Based on the relevant data of National Bureau of Statistics and National Plant Protection Statistics released by National Agro-Tech Extension and Service Center, the changing trends of cotton planting area, occurrence and control of disease and pest, and yield loss in the cotton planting region of the Yellow River Basin were analyzed. [Results] From 1998 to 2023, the cotton planting area of the Yellow River Basin and its proportion to the cotton planting area of the whole country increased first and then decreased. The occurrence area, control area, recover loss, and actual loss showed an overall trend of decreasing-increasing-decreasing. The total control area of disease and pest in cotton planting area of the Yellow River Basin is larger than the occurrence area. The occurrence area, control area, recover loss, and actual loss of pest are greater than that of disease. In order of average annual occurrence area from large to small, the major pests and diseases were Helicoverpa armigera, Aphis gossypii, cotton mirid bug, Tetranychus cinnabarinus, seedling disease, boll disease, Bemisia tabaci, Fusarium wilt, cotton thrips, and Ostrinia furnacalis. Over all, the occurrence area ratio of A. gossypii, cotton mirid bug, B. tabaci, cotton thrips, and boll disease showed an increasing trend, while the occurrence area ratio of H. armigera, seedling disease, and Fusarium wilt showed a decreasing trend, and the occurrence area ratio of T. cinnabarinus and O. furnacalis showed no obvious change. The actual losses of H. armigera, A. gossypii, and boll disease accounted for a large proportion. [Conclusion] The main pests and diseases in the cotton planting area of the Yellow River Basin were identified, which provided theoretical support for the prediction and prevention of cotton diseases and pests in production.

[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.

[Objective] This study aims to clarify the flight capacity of adults of Sylepta derogata. [Methods] Using an insect flying mill system, the flight capacity for 24 h of male and female adults of S. derogata at 1 day old, and flight parameters for 12 h of adults in different genders and ages of S. derogata were measured; the flight distance, flight time, and flight speed of S. derogata under different mating states, ambient temperatures, and complementary nutrition conditions were also measured in the laboratory. [Results] The adults of S. derogata can be divided into three types: short flying type, intermediate flying type, and long flying type. The dividing points of 24 h cumulative flight time of short and intermediate flying type, intermediate and long flying type were 0.90 h and 2.02 h, respectively. The 1- or 2-day-old adults of S. derogata had relatively weak flight capacity, while the 5-day-old adults had the strongest flight capacity. And there is no significant difference in flight parameters between female and male adults of S. derogata at the same ages. Compared with unmated adults, the flight distance, flight time, and flight speed of 5-day-old mated female adults of S. derogata decreased by 49.85%, 35.63%, and 31.97%, respectively; as for 5-day-old mated male adults, the flight distance, flight time, and flight speed significantly decreased by 82.28%, 66.58%, and 53.65%, respectively. The 5-day-old adults of S. derogata were able to fly normally under the temperature of 22-28 ℃. Under different ambient temperatures, the average flight distance and speed of male and female adults were 26 ℃ > 28 ℃ > 22 ℃. The flight time is the longest under 26 ℃. In addition, after feeding on 8% honey water, the flight capacity of 5-day-old unmated male and female adults of S. derogata was significantly better than that of those fed on water or sugar-vinegar solution. [Conclusion] The adults of S. derogata had a certain level of flight capacity, and the ages, mating status, ambient temperature, and complementary nutrition have important effects on its flight capacity.

[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] This study aimed to explore the impact of drought stress, lower canopy shading, and their interaction on the light energy utilization capacity of cotton leaves. [Methods] The photosynthetic physiological indexes, such as plant height, leaf area, leaf thickness, chlorophyll content, and chlorophyll fluorescence parameters, were measured in an artificial climate chamber under drought stress and lower canopy shading conditions using the cotton variety Xinluzao 80 as the material. [Results] Under moderate and severe drought stress, the shading treatment of the lower canopy in cotton significantly increased the plant height and leaf area of lower leaves, significantly decreased the leaf area of upper leaves and leaf thickness of lower leaves, and simultaneously increased the chlorophyll content of upper and lower leaves, which were conducive to the enhancement of the light energy capture capacity, compared with those under the non-shading treatment. Under moderate and severe drought stresses, the actual quantum efficiency of photosystem Ⅱ (Φ_PSⅡ), electron transport rate (ETR), photochemical quenching coefficient (q_P), and non-photochemical quenching (NPQ) of the lower leaves under the shading treatment were reduced compared with those under the non-shading treatment. Φ_PSⅡ of upper leaves under the shading treatment was increased by 19.4% and 31.4%, respectively; ETR was increased by 19.5% and 31.4%, respectively; and q_P was increased by 26.2% and 34.7%, respectively. When shading treatment was applied to the lower leaves, the photochemical reaction in the upper leaves was enhanced under both moderate and severe drought stress. Meanwhile, the heat dissipation capacity of the upper leaves decreased under moderate drought stress but increased under severe drought stress. [Conclusion] The effects of shading treatment on the photosynthetic apparatus of upper leaves were different under different drought stress conditions. Under moderate drought stress, systemic regulation helped to improve the light energy utilization capacity of upper leaves in cotton.

[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 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 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.

[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] 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.