[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 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 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 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] 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 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 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 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] 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 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] 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] 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] 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.