[Objective] The study aims to examine the rhizosphere soil enzyme activity and bacterial community response to foliar application of 1,1-dimethyl-piperidinium chloride (DPC) and sodium nitroprusside (SNP) at the cotton seedling stage, and to screen rhizoshpere events potentially involved in cotton seedling growth. [Method] An upland cotton line A201 was grown in nursery trays under a controlled environment. The treatment with DPC of 50 mg·L^-1 and SNP of 500 μmol·L^-1, respectively, was foliar-applied at the one-leaf-one-heart stage, and the treatment with deionized water application was selected as the control. The rhizosphere soil was sampled to quantify the activities of sucrase, urease, catalase, and alkaline phosphate at the three-leaf-one-heart stage. The rhizosphere bacteria composition examined by 16S rRNA sequence analysis. [Result] The root growth, stem diameter, and dry mass of whole cotton plant were significantly increased by the DPC and SNP treatments. The activities of urease and sucrase were significantly improved by the DPC treatment. SNP application significantly enhanced sucrase activity but significantly decreased urease activity, while DPC treatment and SNP treatment had no significant effect on the activities of catalase and alkaline phosphatase. DPC application increased the relative abundance of Patescibacteria and Simpson's diversity index of soil bacterial community, but reduced the relative abundances of Chloroflexi and Acidobacteriota and Shannon Wiener’s diversity index of soil bacterial community. The results of redundancy analysis on family and genus level showed that the abundances of Saccharimonadaceae and TM7a were higher in the DPC treatment; the abundance of Cellvibrionaceae was greater in the SNP treatment; the abundance of Rhizobiaceae was greater in the DPC and SNP treatments. The control exhibited greater Nitrospiraceae and Nitrospira abundances compared with the DPC and SNP treatments. Urease activity was positively correlated with Saccharimonadaceae and TM7a relative abundances. [Conclusion] DPC and SNP could promote the growth of cotton roots and aerial parts, and influence the soil enzyme activity and bacterial community composition in the rhizosphere.

Cotton has obvious heterosis, which is manifested in traits including yield, fiber quality, and resistance to diseases and insects. Hybrid seed production is a very important step in the utilization of cotton heterosis. Recently, as the cost of manual pollination in seed production increases year by year, the simplified, efficient, and low-cost seed production techniques have become an inevitable trend for future hybrid cotton development. The field practice shows that the use of cytoplasmic male sterile lines not only simplify the procedure of seed production but also save labor costs, so it has become a research hotspot in the utilization of crop heterosis. However, the sterile cytoplasm does have certain impacts on cotton morphogenesis, anther development, yield formation, fiber development, and have negative effects on cotton growth and development, thereby limiting the further promotion and utilization of “three-line (male sterile line, maintainer line, and restoring line)” hybrid cotton. In this paper, the effects of male sterile cytoplasm on the main traits of cotton and the molecular basis for its negative effects were systematically reviewed. And the potential ways to overcome the negative effects of male sterile cytoplasm in cotton were preliminarily discussed, which would provide new ideas for breeding and improvement of cotton cytoplasmic male sterile restorer lines and excellent “three-line” hybrids in the future.

[Objective] This study aims to explore the effects of exogenous methyl jasmonate (MeJA) on cotton tolerance to the heat stress. [Method] The self-bred line ZS08 was used as the test material. Distilled water (CK) and MeJA with different concentrations (200 μmol·L^-1, 400 μmol·L^-1 and 600 μmol·L^-1) were used on plants at the flowering and boll-setting stage. And after the artificial heat stress of 38.0 ℃/30.0 ℃ (day/night) for three days or under natural heat stress of 35.2-37.5 ℃/26.4-27.2 ℃ (day/night) for ten days, the pollen viability, photosynthetic characteristics, antioxidant enzyme activity, malondialdehyde (MDA) content, yield and fiber quality of each treatment were measured. [Result] The pollen viability was reduced under the artificial heat stress. The MeJA treatment of three concentrations all had alleviated the inhibition of heat stress on pollen viability compared with the water control. The net photosynthetic rate (P_n), transpiration rate (T_r) and stomatal conductance (G_s) of the fourth leaf from top of the main stem in the 400 μmol·L^-1 and 600 μmol·L^-1 MeJA treated plants were increased in various degree than those of the control under 2-3 days heat stress by 1.6%-3.7%, 7.2%-15.7%, and 44.4%-53.4%, respectively. The activity of superoxide dismutase (SOD) and peroxidase (POD) of the second leaf from top on the main stem in 400 μmol·L^-1 and 600 μmol·L^-1 MeJA treatment were increased by 3.1%-7.2% and 5.7%-20.0% than those of the control under 2-3 days heat stress. While the content of MDA was reduced by 10.9%-17.9%. Under the natural heat stress, plants which were treated by different concentrations of MeJA had improved boll-setting rate and boll weight in varying degree, and had significantly improved lint yield by 9.0%-18.3% compared with the control. [Conclusion] When encountering heat stress during the flowering and boll-setting stage, the application of MeJA can increase P_n and the activities of SOD and POD, reduce the degree of leaf damage, and improve pollen viability, thereby enhance the heat tolerance of cotton, and reduce the impact of heat stress on boll-setting rate, boll weight, and yield loss.

Cotton is an important cash crop and main raw materials for textile industry, which plays a critical role in economic development of China. Since the founding of the People’s Republic of China, traditional breeding technology has made a great contribution to improve cotton production. With the advancement of sequencing technology, multi-omics research, and gene editing techniques, precise and efficient molecular design breeding has become an inevitable direction for cotton breeding. This review summarizes the present status of cotton production, the history of breeding development, and the achievements of molecular design breeding in genomic research, fiber development, disease resistance and mining of the molecular module of important traits, and proposes directions and path for the future cotton breeding.

[Objective] Based on the integrated technology of water and fertilizer, the effects of different phosphorus (P) application methods were studied, so as to provide a basis for the rational application of P fertilizer in cotton field with drip-irrigation under plastic-film. [Method] The experiment was carried out in Xinjiang cotton field in 2021. Xinluzao 63 was used as the object, and four treatments were set up, CK: no P application; MAP-B: basal application of monoammonium phosphate (MAP), total amount of P₂O₅ was 100 kg·hm^-2 (same as below); MAP-D: basal application of 50% MAP + drip application of 25% MAP at bud stage and 25% at early flowering and boll development stage; MAP-DS: MAP-D + drip application of polyglutamic acid of 50% at bud stage and 50% at early flowering and boll development stage. Soil P content, inorganic P content in different forms, soil P adsorption-desorption characteristics, P use efficiency, and seed cotton yield of different treatments were compared and analyzed. [Result] P application could increase the available P content and total P content in 0-40 cm soil layer at the seedling stage and flowering and boll development stage, and the content of available soil P under MAP-D and MAP-DS treatment was significantly higher than that of other treatments at flowering and boll development stage. Compared with basal application of P (MAP-B), drip application significantly increased the content proportion of dicalcium phosphate (Ca₂-P), octa-calcium phosphate (Ca₈-P) and aluminum bounded phosphate (Al-P), and reduced the proportion of apatite(Ca₁₀-P) at the flowering and boll development stage. The isothermal adsorption and desorption curves of P in 0-40 cm soil layers under different treatments at the seedling stage and flowering and boll development stage showed similar trend, that is, with the increase of P concentration in equilibrium solution, the soil P adsorption increased rapidly at first and then slowly, and with the increase of P concentration in standard solution, the P desorption rate decreased rapidly at first and then tended to be stable. Compared with CK, the seed cotton yield of P application treatments increased. The P use efficiency and seed cotton yield under drip application of P were higher than that of basal application of P (MAP-B). MAP-DS treatment showed the highest P use efficiency and the highest seed cotton yield(6 829.75 kg·hm^-2). [Conclusion] Drip application of P fertilizer combined with polyglutamic acid under the integration of water and fertilizer in Xinjiang cotton planting region is more conducive to the absorption and utilization of soil P for Xinluzao 63, and further improves the P use efficiency and seed cotton yield.

[Objective] The effects of nitrogen fertilizer synergist N-life (main active ingredient: nitrapyrin) on cotton were studied, so as to provide theoretical support for the application of N-life in cotton production. [Method] The field experiment and pot experiment were carried out at Sanya, Hainan province in 2021 and 2022 with Zheda 12 as the experimental material. A field experiment was designed with two factors split-plot. The main plot was N-life application level (1.5 and 0 kg per 667 m²), and the secondary plot was pure nitrogen application level (normal nitrogen rate: 19.0 kg per 667 m², and reduced nitrogen rate: 17.1, 15.2, and 13.3 kg per 667 m²). The effects of different treatments on physiological and biochemical indexes at the seedling stage, flowering and boll stage, and boll opening stage, agronomic traits, yield and fiber quality of cotton were analyzed. And the effect of N-life on nitrogen use efficiency of cotton was studied by pot experiment. [Result] Compared with the control of no N-life, the application of N-life could significantly improve the activities of superoxide dismutase, peroxidase, catalase, and nitrate reductase of cotton leaves, and reduce the malondialdehyde content significantly at the flowering and boll stages and boll opening stages, and increase the net photosynthetic rate in nitrogen reduction treatments. In the two-year pot experiments, N-life application significantly increased the nitrogen content and nitrogen use efficiency of cotton plants, and significantly reduced the nitrogen loss under the same nitrogen application level, also had an increasing effect on the total boll number of cotton plant, seed cotton yield and lint yield. In 2021 and 2022, the seed cotton yield increased by 12.80%-30.63% and 0.08%-5.96%, respectively, and the lint yield increased by 11.33%-34.25% and 0.31%-6.57%, respectively. In addition, the fiber upper half mean length and breaking strength were increased, and micronaire were improved, but N-life had no significant effect on the breaking elongation. [Conclusion] The application of N-life (1.5 kg per 667 m²) could improve the growth, development, and photosynthesis of cotton, enhance the nitrogen use efficiency of plants, and maintain high yield even at the condition of reducing nitrogen by 20% (pure nitrogen dosage of 15.2 kg per 667 m²).

[Objective] This research aims to investigate the role of calcium B-like protein (CBL) gene GhCBL3-A01 in resistance to Verticillium wilt in cotton, so as to provide genetic resource for cotton disease resistance breeding. [Methods] The homologous sequences of GhCBL3-A01 gene were obtained from cotton genomic database for bioinformatic analysis. The relative expression levels of GhCBL3-A01 under Verticillium dahliae, methyl jasminate (MeJA) and H₂O₂ treatments were detected by quantitative real-time polymerase chain reaction (qRT-PCR). The function of GhCBL3-A01 in cotton resistance to Verticillium wilt was analysed by virus-induced gene silencing (VIGS) technique. The functional mechanisms of GhCBL3-A01 were analyzed by detecting the accumulation of reactive oxygen species (ROS) and the expression levels of related genes. [Results] GhCBL3-A01 and its three homologous proteins in upland cotton all contain three typical EF-hand domains of the CBL family. The expression level of GhCBL3-A01 was significantly increased under the treatment of Verticillium dahliae, MeJA, and H₂O₂. Silencing GhCBL3-A01 by VIGS resulted in a significant decrease in rate of diseased plants and disease index, a reduction in the browning degree of vascular bundles, and a decline in the number of hyphae in stem segments, which enhanced the resistance of cotton plants to Verticillium wilt. The expression levels of disease resistance-related genes (PR1, NPR1, PR4, and PDF1.2) and jasmonic acid (JA) signaling pathway genes (AOS1, OPR3, MYC2, and LOX2) were increased, and ROS accumulation was enriched in GhCBL3-A01 silenced cotton plants. [Conclusion] GhCBL3-A01 negatively regulates the resistance of cotton to Verticillium wilt by regulating the expression levels of defense-related genes and JA signaling pathway genes as well as the accumulation of ROS, which is a candidate gene for improving the resistance of cotton to Verticillium wilt.

[Objective] This study aims to screen the suitable nitrogen (N) concentration and investigate its effects on the growth, macronutrients uptake and N use efficiency of cotton at seedling stage. [Methods] HM3097 was used and cultured with nutrient solution for 21 d of six N concentrations with 0, 0.04, 0.4, 1, 4, 8 mmol·L^-1 Ca(NO₃)₂, named N0, N0.04, N0.4, N1, N4, N8, respectively. The root and shoot morphology, biomass, absorption and distribution of macronutrients, photosynthetic capacity, N uptake efficiency (NUpE) and N utilization efficiency (NUtE) of cotton seedlings were determined. [Results] With the increase of N concentration, the growth (include root and shoot), biomass, macronutrients accumulation and photosynthetic capacity of cotton seedlings increased first and then decreased, and 4 mmol·L^-1 Ca(NO₃)₂ was the most appropriate N concentration for cotton at seedling stage, at which the cotton growth was the most vigorous. The maximum accumulations of N, P, K, and Ca of cotton seedlings were 34.4 mg, 6.3 mg, 41.6 mg, and 16.5 mg per plant, respectively, with the ratio of 1∶0.2∶1.2∶0.5. NUpE and NUtE were positively correlated with root-shoot ratio, and the change trend were also consistent with the root biomass distribution proportion, root average diameter, and the root macronutrients distribution proportion, which decreased with the increase of N concentration. In the range of 0-4 mmol·L^-1 Ca(NO₃)₂, the contents of N, K, and Ca, leaf biomass and the shoot macronutrients distribution proportion all increased with the increase of N concentration. [Conclusion] 4 mmol·L^-1 Ca(NO₃)₂ was the most appropriate N concentration for cotton at seedling stage, which could significantly promote the absorption of N, P, K, and Ca of cotton seedlings. 1 mmol·L^-1 Ca(NO₃)₂ could increase the root macronutrients distribution proportion, promote root elongation and proliferation, and improve NUpE and NUtE.

[Objective] This research aims to investigate the optimum plant spacing and density for "Kuanzaoyou" planting pattern in the 7th Division of The Xinjiang Production and Construction Corps, so as to provide a theoretical foundation for establishing a high-yield and efficient cultivation system for local cotton fields. [Methods] Field trials were carried out in 2021-2022, and the planting pattern of "Kuanzaoyou" (76 cm equal row spacing, the film width of 2.05 m) with one film-three rows-three belts was employed. Split-plot design was adopted; the main plot was cotton variety (Xinluzao 61 and K07-12), and the subplot was plant spacing(5.5 cm, 7.5 cm, 9.5 cm, 11.5 cm, 13.5 cm, and 15.5 cm, a total of six levels). The effects of different treatments on cotton growth period, agronomic traits, soil and plant analyzer development (SPAD) value, dry matter mass, canopy structure, yield and fiber quality were studied. [Results] With the increase of plant spacing, the growth period of tested cotton varieties was shortened, the number of fruiting branches per plant, plant height, and stem diameter generally increased, the height of the first fruiting branch node exhibited a fluctuating decrease. SPAD values showed no significant difference under different plant spacing treatments. At the full flowering, peak boll setting and boll opening stage in 2022, with the increase of plant spacing, the dry matter mass of reproductive organs initially increased and then decreased, and the leaf area index (LAI) exhibited a fluctuating decrease, and diffuse non-interceptance (DIFN) showed a fluctuating increase. The differences were not significant for lint percentage, seed cotton yield and lint cotton yield of same cotton variety under different plant spacing treatments in 2021. In 2021 and 2022, the seed cotton yield and lint yield of Xinluzao 61 and K07-12 were higher and the fiber quality was better under the 9.5 cm plant spacing. The fiber quality of Xinluzao 61 was more stable, as there were no significant differences in upper half mean length, uniformity index, micronaire, breaking strength and breaking elongation of the fiber among different plant spacing treatments. [Conclusion] Under the "kuanzaoyou" planting pattern, when the plant spacing was 9.5 cm (theoretical planting density was 138 500 plants·hm^-2), Xinluzao 61 and K07-12 could obtain better LAI and dry matter mass, higher seed cotton yield and lint yield, and better fiber quality could be maintained.

[Objective] This research aims to investigate the sequence structural differences between the mitochondrial genomes of Gossypium harknessii sterile cytoplasm (CMS-D2) and G. trilobum sterile cytoplasm (CMS-D8), which can establish a foundation for the screening and identification of sterility-related genes. [Methods] Based on the sequencing and assembled results of the mitochondrial genome of D2A and D8A, the Synteny and Rearrangement Identifier (SyRI) software was used to identify structural variations, and recombination variation sites containing collinear and non-collinear regions were visualized with Plotsr. The annotation results of the D8A mitochondrial genome were utilized as a reference, and the amino acid sequences encoded by the open reading frame (ORF) annotated in the D2A mitochondrial genome were used for tblastn comparison to screen out the unique ORF in the D2A mitochondrial genome. Subsequently, polymerase chain reaction (PCR) verification, relative expression level analysis, and bioinformatics analysis were performed. [Results] The mitochondrial genomes of the sterile lines D2A and D8A had two partially overlapped and adjacent inverted translocation regions. Seventeen specific ORF were found in D2A mitochondrial genome, and PCR verified the presence of 6 specific ORF (orf114e, orf121b-1, orf121b-2, orf138b-2, orf186a-2, and orf317a-2) in D2A. The relative expression levels of orf121b-1 and orf121b-2 were higher in 3-4 mm flower buds. orf114e, orf186a-2, and orf317a-2 have typical transmembrane domains and chimeric gene structures, which are consistent with some characteristics of sterility genes. [Conclusion] Two adjacent inverted translocation regions were identified between the mitochondrial genomes of D2A and D8A. There are six specific ORF in D2A, among which orf114e, orf186a-2, and orf317a-2 may be potentially related to sporophytic abortion of CMS-D2.

[Objective] This study aims to investigate the regulatory effect of "fertigation adjusted water management" on the physiology and the growth of drip-irrigated cotton in alleviating drought stress, and to enhance cotton yield under limited water resource. [Methods] Using Zhongmian 619 as the test material, two types of irrigation quotas for deficient irrigation (W1: 45 mm) and full irrigation (W2: 54 mm) in combination of three nitrogen input doses, including low nitrogen (F1: 150 kg·hm^-2), medium nitrogen (F2: 225 kg·hm^-2), and high nitrogen (F3: 300 kg·hm^-2) were set. The effects of different irrigation quotas and nitrogen doses on cotton physiological growth indicators and seed cotton yield were analyzed. [Results] The results indicated that increased irrigation quotas promoted cotton growth, enhanced two-year average leaf area index (LAI), relative chlorophyll content (soil and plant analyzer development, SPAD value), and net photosynthetic rate (P_n), while redued the activities of cotton superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and malondialdehyde (MDA) content. With the increase of nitrogen application, LAI, SPAD, P_n, and antioxidant enzyme activity were increased, MDA content was decreased on average, and the influence of water deficiency on cotton development was alleviated. Under W1 treatment, increased nitrogen application improved cotton yield, while under W2 treatment, cotton yield showed the trend of increasing first and then decreasing with the increase of nitrogen application. Under water-nitrogen interaction, the highest two-year average seed cotton yield (6 821.86 kg·hm^-2) was recorded under W2F2 treatment followed by W1F3 treatment (6 717.72 kg·hm^-2). In the technique for order preference by similarity to ideal solution(TOPSIS) analysis, the comprehensive scores of W1F3 and W2F2 were 0.57 and 0.56, respectively, and the differences between the two-year yield of W1F3 and W2F2 treatments were not significant. [Conclusion] Increased nitrogen application under deficit irrigation effectively alleviates the adverse effects of drought on the physiological characteristics and yield in cotton. It is recommended to use 45 mm irrigation quota combined with 300 kg·hm^-2 nitrogen application as the fertigation strategy for the filmless drip-irrigated cotton in southern Xinjiang, to effectively ensure cotton yield under limited water resource.

[Objective] This study aims to monitor the chlorophyll content of cotton leaves by utilizing unmanned aerial vehicle (UAV)-based multispectral technology. [Methods] This study utilized multispectral images of cotton canopies obtained by UAV in southern Xinjiang and employed seven different machine learning methods to estimate the canopy chlorophyll content during the flowering and boll-setting stage which is the critical growth period of cotton. The seven methods include linear regression (LR)-based methods, i.e., simple linear regression, partial least squares regression (PLSR), ridge regression (RR), least absolute shrinkage and selection operator (LASSO) regression, support vector regression (SVR), K-nearest neighbors regression (KNNR), and random forest regression (RFR). [Results] The results showed that compared with the LR method, the RFR, SVR and KNNR can improve the accuracy of prediction model of chlorophyll content in cotton canopies, especially the RFR algorithm, which had the coefficient of determination of 0.742, root mean square error of 1.158 mg·L^-1, residual predictive deviation of 1.969 with the validation dataset. [Conclusion] The use of UAV-based multispectral images with the RFR machine learning method, exhibits the most outstanding performance to estimate the chlorophyll content of cotton leaves and provide essential technical support for precision management in cotton field.

[Objective] This study aims to clarify the sequence structure and expression pattern of two insulin receptor genes in three kinds of winged aphids of Aphis gossypii. [Methods] Based on the whole genome data of A. gossypii, amino acid sequence analysis of two insulin receptor genes (insulin receptor 1, AgInR1; insulin receptor 2, AgInR2) was identified, and phylogenetic analysis of insect InR1 from 17 insects and InR2 from 14 insect was performed. The protein conserved structural domains of insulin receptors were analyzed and motif analysis was conducted using online software. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to analyze the expression patterns of AgInR1 and AgInR2 in wingless female and three kinds of winged aphids at different developmental stages. [Results] The physicochemical analysis showed that AgInR1 and AgInR2 were hydrophilic transmembrane proteins. Phylogenetic analysis showed that InR1 and InR2 of the analyzed insects were clustered into two distinctive groups. The InR1 and InR2 of Hemiptera Aphididae were clustered together with very high bootstrap values, showed close affinity. Conserved domains and motif analyses showed that conserved domain arrangement of InR1 and InR2 from A. gossypii were relatively similar. Compared with AgInR1, AgInR2 lacked one FN3 domain. The results of qRT-PCR showed that the expression level of AgInR1 in the 4th instar and adult stages of the three winged aphids, namely, parthenogenetic wing female, gynoparae, and male was significantly higher than that of parthenogenetic wingless female at the same instar. Meanwhile the expression pattern of AgInR2 in the three kinds of winged aphids was different from that of AgInR1. [Conclusion] AgInR1 might involve in regulating the wing development process in the 4th instar and adult stages of three winged aphids. AgInR2 had a different expression pattern from AgInR1 and might have different biological functions. The study provides theoretical support for further investigation of the role of insulin signaling pathway in wing differentiation of A. gossypii.

[Objective] This research aims to study the effects of the combination of Bacillus subtilis NCD-2 and chemical fungicides on the control of cotton Verticillium wilt, so as to provide a theoretical basis for the control of cotton Verticillium wilt. [Methods] The virulent Verticillium dahliae strain Vd080, a pathogen causing cotton Verticillium wilt was used as the object, and the virulence of 5 fungicides (tebuconazole, fluazinam, prochloraz, mancozeb and chlorothalonil) were determined by growth rate method. The toxicity of NCD-2 to Vd080 was determined by dual-culture method. The fungicides with better compatibility with NCD-2 were selected, and the volume ratio of fungicides and NCD-2 was further determined by Horsfall method. The control effects on cotton Verticillium wilt of different compound treatments were evaluated in the indoor pot experiment. [Results] Among the 5 fungicides, prochloraz had the best inhibitory effect on Vd080, and its median effective concentration (E_C50) was 0.027 mg·L^-1, followed by tebuconazole and fluazinam. The E_C50 of NCD-2 to Vd080 is 2.56 × 10⁷ mL^-1(cell concentration). The compatibility of 0.4 mg·L^-1 fluazinam with 2.56 × 10⁷ mL^-1 NCD-2 was best, reaching 79.19%. The compatibility of 2.0 mg·L^-1 fluazinam and 0.02 mg·L^-1 prochloraz with 2.56 × 10⁷ mL^-1 NCD-2 were 71.29% and 63.20%, respectively. The synergistic effect of 2.56 × 10⁷ mL^-1 NCD-2 was the strongest when mixed with 0.4 mg·L^-1 fluazinam, 2.0 mg·L^-1 fluazinam, and 0.02 mg·L^-1 prochloraz at the volume ratios of 3∶7, 9∶1 and 1∶1, respectively, and the inhibitory effect on Vd080 was the best. The indoor pot experiment showed that when 2.56 × 10⁷ mL^-1Bacillus subtilis NCD-2 and 0.02 mg·L^-1 prochloraz were mixed at the volume ratio of 1∶1, the disease index of cotton Verticillium wilt was the lowest, the control effect was the best (82.81%), and the synergistic effect was good (synergistic coefficient was 23.46). [Conclusion] The combination of 2.56 × 10⁷ mL^-1Bacillus subtilis NCD-2 and 0.02 mg·L^-1 prochloraz at the volume ratio of 1∶1 has a good control effect on cotton Verticillium wilt, and good synergistic effect.

[Objective] Alternative application of pesticides is one of the main strategies for pest resistance management. This study aims to select the insecticides against Aphis gossypii as well as safe to the dominant predatory natural enemy Hippodamia variegata in cotton fields in Xinjiang for further utilization. [Methods] The toxicity of five insecticides, a neonicotinoid insecticide acetamiprid 20% (active ingredient mass fraction) soluble concentrate (SL) as the control, afidopyropen 50 g·L^-1 dispersible concentrate (DC), and three compound pesticides, flonicamid thiamethoxam 60% water dispersion granules (WG), flonicamid acetamiprid 35% WG, and spirotetramat buprofezin 39% suspension concentrate(SC), against A. gossypii and H. variegata were evaluated, and their field control effects against A. gossypii were investigated. [Results] The indoor toxicity test results showed that the toxicity of afidopyropen (LC₅₀=11.66 mg·L^-1) to A. gossypii was higher than that of the control agent acetamiprid (LC₅₀=46.48 mg·L^-1), while the toxicity of flonicamid thiamethoxam, flonicamid acetamiprid, and spirotetramat buprofezin (LC₅₀ > 70 mg·L^-1) was lower than that of the control agent. The toxicity of afidopyropen and three compound agents to H. variegata was lower than that of the control agent. The toxicity of afidopyropen, spirotetramat buprofezin, and flonicamid acetamiprid against A. gossypii was obviously higher than H. variegata, and showed a positive selectivity, while flonicamid acetamiprid and flonicamid thiamethoxam had negative selectivity. The field efficacy test showed that the four tested agents had higher control efficiencies than the control agent. The control efficiency of flonicamid thiamethoxam, afidopyropen, spirotetramat buprofezin, flonicamid acetamiprid, and acetamiprid on A. gossypii at 7 d after treatment was 93.41%, 91.22%, 89.43%, 87.90%, and 79.72%, respectively. [Conclusion] afidopyropen 50 g·L^-1 DC, flonicamid acetamiprid 35% WG, and spirotetramat buprofezin 39% SC not only had better control effect on A. gossypii than acetamiprid 20% SC, but also had higher safety to H. variegata. It is suggested that afidopyropen, flonicamid acetamiprid and spirotetramat buprofezin can be used alternately in the control of A. gossypii in cotton fields of Xinjiang.

[Objective] The aim of this study was to investigate the niche mechanism of weeds in drip-irrigated and machine-harvested cotton fields in North Xinjiang, China. [Methods] A seven-stage visual survey was conducted to investigate the degree of dominance about weeds in 25 cotton fields under drip-irrigated and machine-harvested in 5 regions (143rd corps, 145th corps, and 147th corps of the 8th Division of The Xinjiang Production and Construction Corps, Changji city, Kuytun city) of North Xinjiang. According to the degree of dominance, the important value, the niche breadth, and niche overlap values of 20 main weeds were calculated. The ecological similarity were revealed by detrended correspondence analysis (DCA) sorting. And minimum spanning tree of graph theory cluster analysis were drawn on the basis of the niche overlap value. [Results] The results show that Convolvulus arvensis, Chenopodium album, Amaranthus retroflexus, Solanum nigrum, Phragmites australis, Setaria viridis (L.) Beauv., Abutilon theophrasti Medicus, Hibiscus trionum, and Echinochloa crusgalli with wide niche breadth are the dominant species (malignant weeds) in drip-irrigated and machine-harvested cotton fields in North Xinjiang. The niche overlap values of S. nigrum and C. album, A. theophrasti and A. retroflexus, H. trionum and E. crusgalli, A. retroflexus and E. crusgalli are higher, implying that these weeds may fiercely compete for resources. Based on the relationship between niche overlap values, minimum spanning tree were produced to reflect the similar ecological needs of related weeds. The 20 kinds of main weeds were divided into 4 groups in the minimum spanning tree. In the 25 sites, the integrated ecological demands of 20 kinds of main weeds were sorted by DCA. The results showed that the 9 kinds of malignant weeds clustered in the center of DCA, which are obviously different from those general weeds around DCA. DCA results corresponded well to the minimum spanning tree. [Conclusion] With the increase of years of drip irrigation, there was a extremely significant or significant regression relationship between the dominance values of above mentioned 9 kinds of malignant weeds and years of drip irrigation. There were significant nonlinear regression relationships between their dominant values of C. arvensis and S. viridis and years of drip irrigation, while there were extremely significant linear regression relationships between the dominant values of other 7 kind of malignant weeds and years of drip irrigation.

[Objective] The effect of nitrogen application on cotton yield and its constituent factors is clarified, aiming to provide theoretical reference for the precise application of nitrogen fertilizer and high cotton yield. [Methods] The comprehensive effects and influencing mechanisms of different nitrogen application rates, nitrogen application schemes, and climatic conditions on cotton yield are studied by meta-analysis and path analysis in Xinjiang. [Results] Compared with no nitrogen application, nitrogen application could significantly increase cotton yield with 43.38%. Nitrogen application of 360-480 kg·hm^-2 had the greatest effect on cotton yield. Nitrogen application exceeding this range no longer increased cotton yield significantly, and the recommended economic nitrogen application rate in this study was 360-420 kg·hm^-2. The nitrogen application scheme of 20% of basic fertilizer, 80% of supplementary fertilizer and 6 times of drip application with water at the rate of 6%, 8%, 22%, 25%, 12%, and 7% had the greatest effect on cotton yield. The greatest yield increase was achieved by the nitrogen fertilization program. The most obvious effect of nitrogen application was found in cotton fields with annual evaporation >2 000 mm, annual precipitation <60 mm, annual sunshine time <2 864 h, annual effective cumulative temperature >4 000 ℃, and frost-free period >200 d, and in fields with sandy soil, initial soil organic carbon content <5.8 g·kg^-1, and initial soil available nitrogen content ≤60 mg·kg^-1. The results of the pathway analysis showed that nitrogen application contributed most significantly to the enhancement of cotton yield by increasing the soil nitrate nitrogen content, thereby increasing the cotton leaf area index. [Conclusion] It is suggested that nitrogen application rate of 360 - 420 kg·hm^-2 with the above optimization scheme should be used in Xinjiang cotton area to achieve high cotton yield and reduce environmental risk in drip irrigation cotton fields under film.

[Objective] Spodoptera litura significantly impacts cotton cultivation, while Rehmannia glutinosa is a prevalent agricultural weed. The exploration and application of R. glutinosa for controlling the S. litura hold crucial relevance for the sustainable production of cotton. [Methods] The effects of root or leaf dry powder of R. glutinosa on the mortality, developmental duration, and body weight of S. litura larvae were preliminarily determined by mixing the dry powder and feed with the mass ratios of 1∶3, 1∶6, 1∶9, and 1∶18, respectively. Additionally, the influence of 95% ethanol extracts of root or leaf powder of R. glutinosa (the ratios of dry powder to solvent were 1∶50, 1∶30, and 1∶10) on the mortality of 1st to 6th instar S. litura larvae were studied by film-coating technique. [Results] The incorporation of R. glutinosa root or leaf dry powder into the larvae's diet notably affected their growth and development. An increase of the root or leaf dry power content in the diet led to higher larval mortality, extended developmental periods, and decreased body weight. The most significant inhibitory effect occurred when the mass ratio of root or leaf dry powder to feed was 1∶3. The ethanol extracts of R. glutinosa root or leaf exhibited a certain inhibitory effect on the younger larvae, while with diminished efficacy on older larvae. As the concentration of R. glutinosa extract increased, the mortality of younger larvae increased at the same testing period. Optimal toxicological effects on 1st to 6th instar larvae were observed when the root or leaf dry power of R. glutinosa to solvent ratio was 1∶10. [Conclusion] R. glutinosa shows a definitive inhibitory effect on S. litura. In a certain range, the greater dosage of R. glutinosa root or leaf dry powder has the stronger inhibitory effect. This finding lays a theoretical groundwork for the strategic utilization of agricultural weed resources in developing plant-derived insecticides.