In order to understand the salt tolerance of different genotypes of upland cotton germplasm resources, this study subjected 40 samples to salt stress using NaCl solutions with concentrations of 0, 50, 100, 150, 200, and 300 mmol/L, and measured relevant indicators during the seed germination period. Principal component analysis and membership function analysis were used to comprehensively evaluate the salt tolerance of seeds during germination. The results showed that (1) under the stress of high concentration NaCl solution, germination potential, germination rate, hypocotyl length, root length and fresh matter mass per plant all showed a downward trend. (2) Correlation analysis, principal component analysis and membership function comprehensive evaluation were performed on 30 materials with germination rate >50% at A4 concentration, four materials with strong salt tolerance were obtained, namely ‘Han 8266’, ‘Rihui Mian 6’, ‘Zhong R971708’ and ‘Kuaiyu 2’. (3) Through cluster analysis, at the Euclidean distance of 5, the 30 materials could be divided into 3 categories. There were 1 salt-tolerant material in Category I, 18 moderately salt-tolerant materials in Category II, and 11 salt-sensitive materials in Category III.

In order to understand the current situation of cotton stalks crushing and returning to the field for decomposition in Xinjiang, we took the returned cotton stalks and soil as the research objects to investigate the effect of cotton stalks returning to the field on the nutrient content of the soil in the soil layer of 0-30 cm. Soil samples were collected from 0-10, 10-20 and 20-30 cm in Tumushuke, Korla, Kuitun and Shihezi areas by field research method and five-point sampling method. The crushed length of cotton stalks in the field was 17%-18% at <10 cm, about 60% at 10-20 cm, and about 25% at >20 cm; the distribution of the length of cotton stalks in the depth of soil layer from 0 to 30 cm was 52% at <10 cm, 35% at 10-20 cm, and 13% at >20 cm; soil samples collected from 0-10, 10-20 and 20-30 cm of cotton fields were analyzed. The results showed that the soil moisture content of cotton fields in Tumushuke and Korla was 10%-18%, the organic matter was about 20 g/kg, and the quick-acting potassium was about 200 mg/kg; and that of cotton fields in Kuitun and Shihezi was 16%-20%, the organic matter was about 30 g/kg, and the quick-acting potassium was about 300 mg/kg. The highest quick-acting phosphorus was 181.44 mg/kg in Kuitun site and the lowest was 7.34 mg/kg in Korla, showing that the mean nutrient value in the southern border area was lower than that in the northern border. There are differences in the effects of returning cotton stalks to the field on soil properties in various regions, and these differences are not only affected by natural environmental factors, but also closely related to different grain sizes of cotton stalks, different burial depths and other factors. Cotton stalks crushed and returned to the field need to be adapted to local conditions, scientific return to the field.

The study investigated the impact of adding equal carbon amounts of cotton stalks and biochar to soil on soil physical and chemical properties and nutrient transformation enzyme activities, aiming to support sustainable agriculture in drip-irrigated cotton fields in arid regions. The experiment included three treatments: no residue returning (CK), cotton stalk returning (ST, 6 t/hm²) and biochar returning (BC, 3.7 t/hm²). The results showed that both cotton stalks and biochar significantly increased the proportion of large soil aggregates compared with CK, the mean mass diameter and geometric mean diameter of aggregates were significantly improved, aggregate stability was improved, and soil porosity and water content were enhanced. Large aggregates and water content increased by 107.7%, 58.5% and 42.1%, 28.5%, but the soil bulk density was significantly reduced. Compared with CK, both treatments elevated soil cation exchange capacity (CEC), organic matter, total nitrogen, alkali-hydrolyzable nitrogen, available phosphorus and available potassium, CEC increased by 4% and 12%, with biochar being more effective in enhancing CEC, organic matter, carbon-nitrogen ratio, available phosphorus and available potassium. Cotton stalks were more effective in increasing total nitrogen and alkali-hydrolyzable nitrogen. Both treatments increased the activities of soil sucrase, β-glucosidase, cellulase, dehydrogenase and alkaline phosphatase, with cotton stalks also elevating urease and alkaline protease activities, while biochar reduced them. Correlation analysis indicated that total nitrogen and alkali-hydrolyzable nitrogen were primary factors promoting activities of sucrase, β-glucosidase, cellulase, dehydrogenase and alkaline phosphatase enzyme, while soil pH and bulk density inhibited them. Both treatments significantly enhanced the absorption of nitrogen, phosphorus and potassium in cotton, promoting growth and development, and increasing cotton seed yield by 12.6% for cotton stalks and 10.2% for biochar. In conclusion, returning cotton stalks and biochar to the soil improved soil structure, increased nutrient content and enzyme activities, and promoted nutrient absorption in cotton, leading to a significant increase in cotton seed yield.

By analyzing the effects of different frequencies of drip irrigation on the emergence rate, agronomic shape and root distribution of cotton fields with different soil water contents under loamy soil conditions in southern Xinjiang, the suitable frequency of emergence water for ‘dry sowing and wet emergence’ under loamy soil conditions was explored, which provided theoretical support for ‘one sowing and whole seedling’ of cotton in southern Xinjiang. Taking upland cotton ‘J8031’ as the test material, under the condition of soil moisture content of 10%-15%, 15%-20% and 20%-25%, the seedling emergence water was set up for 1, 2 and 3 times, respectively. With the increase of drip irrigation frequency, the soil compaction decreased, and the soil EC value decreased gradually. The soil EC value of the same soil depth was less than that of the film edge, and the soil EC value of 5 cm soil depth was less than that of 10 cm under the same hole or film edge position. The emergence rate was the highest when the seedling water was dripped twice, and the lowest when the seedling water was dripped once, and the phenomenon of ‘decapitated seedling’ and ‘stuck neck’ appeared. With the increase of water frequency, plant height, stem diameter and aboveground dry matter accumulation showed a gradually increasing trend. The high frequency of seedling water was closely related to root growth and development. The increase of the frequency of seedling water dripping and the water-oriented characteristics of the lateral root system gradually increased the root weight density, root length density, root surface area and root volume, but the root diameter was the smallest when the seedling water was dripped three times. Under loam soil conditions, when the soil water content was 10%-15%, 15%-20%, and 20%-25%, the emergence water for ‘dry sowing and wet emergence’ dripped twice could meet the germination and emergence of cotton seeds, and the agronomic traits and root morphology were better at the seedling stage.

This paper aims to improve polyethylene film to prevent residual film infiltration and soil pollution under the premise of keeping temperature and moisture. The common film and the modified biodegradable polyethylene film were used in the film mulching experiment by using the test method and the comparison method. The results of laboratory tests showed that after 72 hours of ultraviolet aging treatment and infrared characterization, the modified biodegradable polyethylene film was almost completely degraded, while the ordinary film had almost no change. Under the same thickness and test conditions, the properties of the modified biodegradable polyethylene film were basically the same as those of the ordinary film. The field experiment of two kinds of films applied to cotton field in Dezhou City, Shandong Province showed that the moisture retention performance of the degradable polyethylene film was equivalent to that of the common film, and better than the bare land. And the degradation effect of degradable mulching film was in line with the design goal. The modified biodegradable polyethylene film used in this paper has the same performance as common mulch film, and has better degradation ability, which provides a new product for preventing residual film penetration and soil pollution.

The greenhouse gas emission rules under different farmland management methods were revealed, and the influencing factors and action mechanisms were expounded, so as to deal with greenhouse gas emissions from saline-alkali land in extremely vulnerable areas, mitigate climate change, and provided theoretical basis for greenhouse gas emission reduction in China. An extremely saline soil with electrical conductivity of 9.35 mS/cm and pH of 8.38 was used for indoor culture experiments. Three temperature gradients were set as 15, 25 and 35℃; three nitrogen application levels were set as 0, 120 and 240 kg N/hm² and three biochar application levels were set as 0, 5 and 10 t/hm². All treatments were carried out under 60% field water holding capacity and cultured for 45 days. The results showed that temperature and nitrogen application significantly increased CO₂ and N₂O emissions, and short-term application of biochar could reduce N₂O emissions. (1) Under the same temperature and biochar conditions, the application of nitrogen fertilizer significantly increased greenhouse gas emissions. The cumulative emissions of CO₂ and N₂O at 120 kg N/hm² were 2.02 times and 1.28 times of the control, respectively. The cumulative emissions of CO₂ and N₂O were the highest when nitrogen fertilizer rate was 240 kg N/hm², which were 2.22 times and 1.64 times of the control, respectively. (2) Under the same temperature and nitrogen fertilizer conditions, the application of biochar significantly reduced the emission of N₂O. Compared with the control, when the application rate of biochar was 5 t/hm², the emission of N₂O was reduced by 7%. The amount of biochar applied was 10 t/hm², and the N₂O emission was reduced by 13%. (3) Compared with 15℃, cumulative CO₂ and N₂O emissions at 25℃ increased by 11.34 g C/kg and 39.69 mg N/kg, respectively; the cumulative emissions of CO₂ and N₂O at 35℃ were the largest, increasing by 48.17 g C/kg and 69.69 mg N/kg, respectively. In summary, this study demonstrates that in the management of extreme saline-alkali soils in agricultural fields, reasonable control of temperature, nitrogen fertilization strategies, and the use of biochar are of significant importance for regulating greenhouse gas emissions.

In order to study the response of different plant types of sea-island cotton to planting density, two loose plant types‘Yuanlong28’, ‘Yuanlong 61’and compact plant type ‘Xinhai 45’, were selected as materials for research, and the variations in agronomic, quality and yield traits under four distinct planting densities were studied. The results showed that with the increase of planting density, plant height, plant width, bolls per plant, boll weight, seed index, micronaire, upper half mean length, fiber strength, length uniformity and fiber maturity showed a decreasing trend, while bolls per plant in middle and lower part of fruit branches increased. The plant height, plant width and bolls per plant in flowering and boll stage were significantly different among different densities. The loose plant type materials had long fruit branches, stable growth and great adaptability, and the suitable planting density was 0.21 million-0.27 million plants/ha. The compact plant type material had the characteristics of short fruit branches, fast growth, vigorous, strong boll setting, and high requirements for nutrients. Cultivation methods should be adjusted according to the actual growth, so that the growth advantage can be transformed into the yield advantage, and the yield can be further improved.

In order to comprehensively understand the production performance of the newly state-approved cotton variety ‘Liaomian 15’, based on the data of the 2016-2018 regional tests of medium-ripe conventional varieties in the cotton area of the Yellow River Basin, the yield, high stability coefficient, yield increase point rate, variety deviation degree and yield components were used to comprehensively evaluate the high yield performance, stable yield property and adaptability of ‘Liaomian 15’. The results showed that from 2016 to 2018, the average lint yield of ‘Liaomian 15’ was 1712 kg/hm², which was increased by 16.77% compared to the control ‘Shikang 126’. Out of 50 experimental points in three years, 49 sites increased production. Path analysis showed that the total number of bolls, boll weight, and lint percentage had a direct positive effect on the lint yield of ‘Liaomian 15’. The direct contribution to the lint yield was as follows: total number of bolls>lint percentage>boll weight. ‘Liaomian 15’ was an excellent variety suitable for large-scale promotion in the cotton area of the Yellow River Basin. In production, it was necessary to coordinate the relationship between the three factors while ensuring the total number of bolls, so as to maximize the production potential of the variety and contribute to ensuring the safety of national cotton production.

The study aims to explore physiological mechanisms of salt tolerance in cotton during seed germination stage. Using ‘Xinluzao NO.61’, a major local cotton variety, as the test material, the effects of ascorbic acid (AsA) soaking on key germination characteristics and physiological indicators of cotton seeds were analyzed under different types of salt stress. The results showed that the germination of cotton seeds decreased with increasing salt stress concentration; Under NaCl, Na₂SO₄, and Na₂CO₃+NaHCO₃ stress, the soaking with AsA enhanced the germination characteristics of cotton seeds, among them, the germination rate of cotton seeds increased the most, increasing by 55.32%, 56.10%, and 44.0% compared to the control, respectively, and the optimal AsA soaking concentration for improving salt tolerance was selected as 0.10 mmol/L, 0.10 mmol/L, and 0.15 mmol/L; during the germination process under salt stress, the activities of SOD, POD and CAT, and the contents of soluble protein and soluble sugar in cotton seeds soaked with AsA increased，while the content of MDA and H₂O₂ decreased, and all showed significant differences from the control group. It is concluded that AsA soaking can improve the salt tolerance of cotton seed during germination, as it enhances the main antioxidant enzyme activity, increases the content of osmotic substances, and alleviates membrane lipid peroxidation of cotton seed.

【Objective】By analyzing the effects of different strip intercropping patterns on cotton biomass accumulation and distribution, photosynthetic performance and yield, the potential mechanism of cotton yield increase and efficiency under different strip intercropping patterns was explored, so the optimum cotton strip intercropping planting pattern suitable for the Yangtze River basin was proposed. 【Method】A two-point field experiment was conducted with monocropping cotton (MC) as the control, and three intercropping patterns of cotton-sweet potato (CS), cotton-bean (CB) and cotton-melon (CM) were set up, while two strip configurations were as follows: 3:3 and 4:2. The effects of different strip intercropping patterns on biomass accumulation, organ distribution, light and performance and yield of cotton were analyzed, and the ratio of cotton to soil equivalent and economic benefit under different strip intercropping patterns were calculated and compared. 【Result】Compared with MC, The average seed cotton yield and lint cotton yield under strip intercropping patterns in two field trials were significantly increased. Among them, compared with cotton intercropping with sweet potato and cotton intercropping with melon, the cotton intercropping with bean had the most significant advantage in cotton yield. and the yield of CB 3:3 pattern seed cotton was 23.20% and 32.46% higher than MC, respectively; compared with MC, the yield of lint was increased by 26.43% and 32.53%, respectively; the main reason was that the number of bolls per plant was 26.58 and 24.43, respectively, which were significantly increased by 22.21% and 28.85% compared with that of single cropping. The boll weight of cotton intercropping with sweet potato CS 4:2 in Hengyang was 3.01% lower than MC. At full boll period, the biomass accumulation of cotton plant was higher than MC, and the proportion of reproductive organs allocation was significantly higher than that of stem and leaf, the proportion of reproductive organs in each intercropping pattern in Hengyang was more than 50%. From full squaring period to boll opening period, the leaf area index of all treatments showed a trend of first increasing and then decreasing. Compared with MC, the relative chlorophyll content and net photosynthetic rate of cotton plants were significantly increased under each intercropping pattern at full boll period. Among them, the cotton intercropping with beans at two field trials was the most advantageous. The net photosynthetic rate was 6.25%-6.29% and 2.85%-2.90% higher than MC, respectively, so it could effectively improve the photosynthetic performance of cotton plant and finally achieve yield increase. Under different strip intercropping patterns, the total economic benefit of cotton field in the two field trials increased by 1.24-2.70 times and 1.42-3.09 times, respectively, compared with MC. From the point of view of partial land equivalent ratio of cotton, except CS 4:2 pattern in Changsha, the other strip intercropping pattern in two field trials showed the advantage of intercropping yield. 【Conclusion】The increase of yield in different strip intercropping patterns was mainly achieved through the improvement of biomass accumulation, assimilate allocation and photosynthetic performance. The best performance was cotton intercropping with sweet potato CS 3:3 pattern, which ensured higher yield and intercropping advantages, and was suitable for spreading planting in the Yangtze River basin.

The effects of mepiquat chloride (DPC) on Cry1Ac protein contents in Bacillus thuringiensis (Bt) cotton boll shells under high temperature and drought stress were investigated to provide a theoretical reference for Bt cotton breeding and high-yield and high-efficiency cotton cultivation.  This study was undertaken on the Bt cotton cultivar ‘Sikang 3’ during the 2020 and 2021 growing seasons at Yangzhou University Farm, Yangzhou, China.  The potted cotton plants were exposed to high temperature and drought stress, and 20 mg L⁻¹ DPC and water (CK) were sprayed on cotton plants.  Seven days after treatment, Cry1Ac protein content, α-ketoglutarate content, pyruvic acid content, glutamate synthase activity, glutamic oxaloacetic transaminase activity, soluble protein content, and amino acid content were measured, and transcriptome sequencing was performed.  DESeq was used for differential gene analysis.  Under the DPC treatment, in contrast with the water treatment (CK), Cry1Ac protein content increased by 4.7-11.9%.  α-Ketoglutarate content, pyruvic acid content, glutamate synthase activity, glutamic oxaloacetic transaminase activity, soluble protein content, and amino acid content all increased.  Transcriptome analysis revealed that there were 7542 upregulated genes and 10449 downregulated genes for DPC vs. CK.  GO and KEGG analyses showed that differentially expressed genes were mainly involved in biological processes, such as amino acid metabolism and carbon metabolism.  Genes coding 6-phosphofructokinase, pyruvate kinase, glutamic pyruvate transaminase, pyruvate dehydrogenase, citrate synthase, isocitrate dehydrogenase, 2-oxoglutarate dehydrogenase, glutamate synthase, 1-pyrroline-5-carboxylate dehydrogenase, glutamic oxaloacetic transaminase, amino-acid N-acetyltransferase, and acetylornithine deacetylase were all significantly upregulated.  DPC increased pyruvate, α-ketoglutarate, and oxaloacetate by increasing the operating rate of the glycolytic pathway, the citric acid cycle.  It also significantly up-regulated the genes encoding glutamate synthase and pyrrolidine-5-carboxylic acid dehydrogenase, and down-regulated the genes encoding glutamine synthetase as well as up-regulated the genes encoding glutamate oxaloacetate transaminase and N-acetylglutamate synthetase.  Therefore, the synthesis ability of aspartic acid, glutamic acid, pyruvate, and arginine was increased by DPC, and then Cry1Ac protein contents were increased by regulating carbon and amino acid metabolism.

Two Cotton Research Institute (CRI) near-isogenic lines, CRI-12 glanded and CRI-12 glandless, were used to pinpoint potential genes and metabolic pathways linked to gossypol biosynthesis through transcriptome sequencing.  We discovered more than 235 million clean reads and 1,184 differentially expressed genes (DEGs).  Consecutively, we conducted a weighted gene co-expression network analysis and found strong correlation of white and yellow modules containing GhTPS (GH_D09G0090) and GhCYP (GH_D05G2016) hub genes with the gossypol content.  The importance of the GhTPS and GhCYP genes was demonstrated using RT‒qPCR, virus-induced gene silencing (VIGS) and target metabolite analysis.  Silencing of these genes resulted in fewer glands on both leaves and stems two weeks after the infection, as compared to the wild type.  In addition, a total of 152 metabolites were identified through targeted metabolite profiling.  Differential metabolite screening revealed 12 and 18 significantly different metabolites in TRV:GhTPS and TRV:GhCYP plants vs. control group, respectively, showing reduction in accumulation of metabolites compared to the control.  The content of hemigossypol, the final product of gossypol biosynthesis, was also reduced, as revealed by target metabolite analysis, suggesting the role of these genes in the gossypol biosynthetic pathway.  Furthermore, a highly significant difference in gossypol content between the glanded and glandless lines was recorded.  The findings of this study reveal a strong link between the gossypol content and GhTPS and GhCYP hub genes, suggesting their role in the gossypol biosynthetic pathway to reduce the accumulation of hemigossypol, which may offer new comprehension into the regulatory checkpoints of the gossypol biosynthesis pathway in cotton.

Improving plant resistance to Verticillium wilt (VW), which causes massive losses in Gossypium hirsutum, is a global challenge.  Crop needs to efficiently allocate their limited energy resources to balance growth and defense.  However, few transcriptional regulators specifically response to V. dahliae and the underlying mechanism in cotton has not been identified.  In this study, we found that the that expression of the majority R2R3-MYB in cotton is significantly changed relative to other MYB types by V. dahliae infection.  Of which, a novel R2R3-MYB TF GhMYB3D5, specifically response to V. dahliae, was identified. GhMYB3D5 did not express across 15 cotton tissues at normal condition, but drastically induced by V. dahliae stress.  We functionally characterized its positive role and underlying mechanism in VW resistance.  Upon V. dahliae infection, the up-regulated GhMYB3D5 bound the GhADH1 promoter and activated GhADH1 expression, moreover, GhMYB3D5 physically interacted with GhADH1 and furtherly enhanced the transcriptional activation to GhADH1.  Consequently, the transcriptional regulatory module GhMYB3D5-GhADH1 promoted lignin accumulation via improving the transcriptional levels of genes related to lignin biosynthesis (GhPAL, GhC4H, Gh4CL, and GhPOD/GhLAC) in cotton, thereby enhancing the cotton VW resistance.  Taken together, our results demonstrated that the GhMYB3D5 promoted a defense-induced lignin accumulation, which regarded as an effective manner in orchestrating plant immunity and growth.

棉花不仅是重要的天然纺织纤维作物，也是一种重要的食用油来源。棉籽油中约含14%的油酸和59%的亚油酸。提高油酸含量有助于增强棉籽油的氧化稳定性和营养价值。磷脂酰胆碱:二酰基甘油胆碱磷酸转移酶(PDCT)是调控磷脂酰胆碱与二酰基甘油转化的关键酶。本研究克隆了四个棉花PDCT同源基因，分别命名为GhPDCT1-4。发现GhPDCT3和GhPDCT4几乎不表达，而GhPDCT1在棉籽油分积累时期显著上调。利用CRISPR/Cas9系统同时敲除序列高度相似的GhPDCT1和GhPDCT2基因后，ghpdct突变体种子中油酸含量从野生型的14.46%增加到16.49%，而亚油酸含量从59.98%减少到52.83%。此外，ghpdct种子中的棕榈酸和硬脂酸含量也有所增加。本研究获得了油酸含量提高的新型棉籽油种质，有望提升棉花作为油料作物的经济和营养价值，推动棉花产业的升级。

EPSPS is a key gene in the shikimic acid synthesis pathway and has been widely used in breeding crops with herbicide resistance.  However, its role in regulating cell elongation is poorly understood.  Through the overexpression of EPSPS genes, we generated lines resistant to glyphosate that exhibited an unexpected dwarf phenotype.  A representative line, DHR1, exhibits a stable dwarf phenotype throughout its entire growth period.  Except for plant height, the other agronomic traits of DHR1 were similar to its transgenic explants ZM24.  Paraffin section experiments showed that DHR1 internodes were shortened due to reduced elongation and division of internode cells.  Exogenous hormones confirmed that DHR1 is not a classical BR- or GA-related dwarfing mutant.  Hybridization analysis and fine mapping confirmed that the EPSPS gene is the causal gene for dwarfism, and the phenotype can be inherited in different genotypes.  Transcriptome and metabolome analyses showed that genes associated with the phenylpropanoid synthesis pathway were enriched in DHR1 when compared with ZM24.  Flavonoid metabolites were enriched in DHR1, whereas lignin metabolites were decreased.  The enhancement of flavonoids likely resulted in differential expression of auxin signal pathway genes and altered the auxin response, subsequently affecting cell elongation.  This study provides a new strategy for generating dwarfs and will accelerate advancements in light simplification of cultivation and mechanized harvesting for cotton.

Cotton fiber quality is a persistent concern that determines planting benefits and the quality of finished textile products.  However, the limitations of measurement instruments have hindered the accurate evaluation of some important fiber characteristics (such as fiber maturity, fineness, neps), which in turn has impeded the genetic improvement and industrial utilization of cotton fiber.  Here, twelve single fiber quality traits were measured using Advanced Fiber Information System (AFIS) equipment among 383 accessions of upland cotton (Gossypium hirsutum L.).  Also, eight conventional fiber quality traits were assessed by the High Volume Instrument (HVI) system.  Genome-Wide Association Study (GWAS), linkage disequilibrium (LD) block genotyping and functional identification were conducted sequentially to uncover the associated elite loci and candidate genes of fiber quality traits.  As a result, the pleiotropic locus FL_D11 regulating fiber length related traits was again identified in this study.  More importantly, three novel pleiotropic loci (FM_A03, FF_A05, FN_A07) regulating fiber maturity, fineness and neps respectively were detected on the basis of AFIS traits.  Numerous highly-promising candidate genes were screened out by integrating RNA-seq and qRT-PCR analyses, including the reported GhKRP6 for fiber length and newly identified GhMAP8 for maturity and GhDFR for fineness.  The origin and evolution analysis of pleiotropic loci indicated that the selection pressure on FL_D11, FM_A03 and FF_A05 increased as the breeding period approached and the origins of FM_A03 and FF_A05 were traced back to cotton landraces.  These findings reveal the genetic basis underlying fiber quality and provide insight into genetic improvements and textile utilization of fiber in G. hirsutum.

Leaves are the main places for photosynthesis and organic synthesis of cotton.  Leaf shape has important effects on the photosynthetic efficiency and canopy formation, thereby affecting cotton yield.  Previous studies have shown that LMI1 is the main gene regulating leaf shape. In this study, the LMI1 gene (LATE MERISTEM IDENTITY1) was inserted into the 35S promoter expression vector, and cotton plants overexpressing LMI1(OE) were obtained through genetical transformation.  Statistical analysis of the biological traits of T₁ and T₂ populations showed that compared to wild type (WT), OE plants had significant larger leaves, thicker stems and significantly increased dry weight.  Furthermore, plant sections of the main vein and petiole showed that the number of cell in those tissues of OE plants increased significantly.  In addition, RNA-seq analysis revealed differential expression of genes related to gibberellin synthesis and NAC gene family (genes containing the NAC domain) in OE and WT plants, suggesting that LMI1 is involved in secondary wall formation and cell proliferation, and promotes stem thickening.  Moreover, GO (Gene Ontology) analysis enriched the terms of calcium ion binding, and KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis enriched the terms of fatty acid degradation, phosphatidylinositol signal transduction system, and cAMP signal pathway.  These results suggested that LMI1 OE plants were responsive to gibberellin hormone signals, and altered messenger signal (cAMP, Ca²⁺) which amplified this function, to promote the stronger above ground vegetative growth.  This study found the LMI1 soared the nutrient growth in cotton, which is the basic for higher yield.

In order to clarify the sensitive response of different main cotton varieties to chemical topping agents in Bayingol Mongolian Autonomous Prefecture of Xinjiang, four local main cotton varieties were selected as the research objects to study and analyze the effects of DPC (25% slow-release emulsion in water) treatment with chemical topping agents on plant height, LAI, aboveground biomass accumulation, yield and quality of different cotton varieties. The results showed that 30 days after topping, the plant height of different cotton varieties was significantly higher than that of artificial topping by 4.09%-7.54% (P<0.05), among which ‘Ba 43541’ increased the least. LAI of different cotton varieties under two topping methods ranged from 2.96 to 4.03. Compared with before topping, LAI of cotton variety ‘Ba 43541’ increased the most under chemical topping method. The changes of leaves, stems, buds and total dry matter mass of different cotton varieties under two topping methods were different, but the changes of dry matter mass under two topping methods were not significant (P>0.05). Compared with manual topping, chemical topping had little effect on fiber length, uniformity, specific strength, micronaire value and elongation of different cotton varieties, and the difference was significant. Compared with manual topping, the yield of seed cotton of different cotton varieties increased by 0.35%-2.49% under chemical topping, among which the yield of cotton variety ‘Ba 43541’ was the highest, with 163.15 kg/hm², followed by ‘Xinluzhong 71’, ‘Xinluzhong 78’ and ‘Xinluzhong 81’. ‘Ba 43541’, the main cotton variety in Bayingol, is the most sensitive to chemical topping agent, and has the best effect of chemical capping, and has the potential to increase production.

【Objective】Exploring the genetic loci and related genes that control cottonseed size traits to lay a foundation for subsequent study on the molecular mechanism cottonseed size formation. 【Method】The upland cotton recombinant inbred line (RIL) population composed of 300 lines was used as the research material. Seven phenotypic traits including cottonseed index (SI), seed length-cutting acreage (SLA), seed length-cutting perimeter (SLP), seed length (SL), seed width (SW), length-width ratio (LWR) and seed roundness (SR) were evaluated in four environments. The RIL population was genotyped by liquid phase chip strategy. The high-quality single nucleotide polymorphism (SNP) markers and phenotypic data were subjected to perform genome-wide association study (GWAS), and quantitative trait nucleotides (QTNs) associated with cottonseed size-related traits were mined. The genetic effects of QTNs were analyzed to identify candidate genes. 【Result】Seven cottonseed size-related traits showed a continuous normal distribution in four environments, which expressed a sizable phenotypic variation. The coefficient of variation ranged from 1.82% to 10.70%. The influencing effect on trait formation were basically as genotype>environment>genotype × environment, indicating suitability for GWAS analysis of these results. Correlation analysis showed that the seed index was significantly correlated with SLA, SLP, SL and SW, and LWR was significantly correlated with SR, indicating the possible existence of pleiotropic loci. GWAS was performed using the 3VmrMLM model, and a total of 47 QTNs were associated with these seven traits. A total of 11 QTNs were associated on chromosome A07, of which three physical loci in the region of 71.99-72.87 Mb, A07:71993462, A07:72067994 and A07:72198802 were very close and simultaneously associated with SI, SLA, SLP, SL and SW in four environments. The average value of R2 between markers was>0.8 (P<0.001), showing a large linkage disequilibrium. Genetic effect analysis showed that there were two haplotypes in this region. Among these cottonseed size relating traits, haplotype Ⅱ and haplotype I were significantly different, indicating that these loci directly affected cottonseed size traits and could be used for molecular marker-assisted selection. The expression patterns of the genes in the interval were analyzed using TM-1 transcriptome data. The results revealed that Gh_A07G1767 was preferentially expressed and Gh_A07G1766 specifically expressed at the stage of cottonseed development. These results speculated that these genes may play an important role in the growth and development of cottonseed.【Conclusion】47 QTNs were identified, and two candidate genes related to cottonseed development were screened.