Cotton Growth Period Research Articles

Effects of chemical regulation on the growth, yield and fiber quality of cotton varieties with different plant architectures

Chemical regulation has beneficial effects on the growth, yield, and fiber quality of cotton with different plant architectures. This study aimed to investigate the combined effects of chemical regulators such as mepiquat chloride (1,1-dimethyl-piperidiniuchloride, DPC), chlormequat chloride (CCC), thidiazuron (TDZ), and ethephon (ETH) during the growth period of cotton. Different combinations of chemical regulators were applied to examine the growth, development, yield, and quality of cotton. The results showed that the application of different chemical regulators had varying effects on the yields of the two cotton varieties with distinct plant architecture. Specifically, K1C1 (before and after topping with 1:1 25% DPC, 50% TDZ, and 40% ETH) and K2C2 (before topping with 25% DPC and after topping with 50% CCC, 50% TDZ, and 40% ETH) were sprayed on ‘Wankemian-1’ and ‘Wanmian-191’, thereby increasing the cotton yield. The K2C2 treatment increased the upper half mean length and fiber strength of the two varieties but decreased the fiber length uniformity index. The fiber strength, fiber length uniformity index, and spinning consistency index of ‘Wankemian-1’ were higher than those of ‘Wanmian-191’. Based on comprehensive yield, quality, and economic benefits, K1C1 and K2C2 were determined to be the most effective chemical regulators of ‘Wankemian-1’ and ‘Wanmian-191’, respectively.

Increasing dissolved oxygen concentration of irrigation water is beneficial to nitrogen uptake of cotton under mulched drip irrigation

ContextEnhancing crop nitrogen absorption is crucial for improving nitrogen fertilizer utilization efficiency. Soil oxygen conditions play a vital role in influencing crop nutrient uptake. However, the impact of dissolved oxygen concentration in irrigation water on cotton’s nitrogen absorption remains unknow under mulched drip irrigation conditions. RESEARCH QUESTION: This study aimed to investigate whether the dissolved oxygen concentration in irrigation water affects cotton’s nitrogen uptake. METHODS: Urea was utilized as the nitrogen fertilizer, and 5 dissolved oxygen concentration of irrigation water were set in the experiment by adding sodium percarbonate (CK: 3.9 mg L−1, CO1: 9.2 mg L−1, CO2: 13.3 mg L−1, CO3: 17.3 mg L−1, CO4: 25.5 mg L−1). RESULTS: The results showed that increasing the dissolved oxygen concentration in irrigation water could increase the soil urease activity and bacterial operational taxonomic units (OTU), which may be beneficial to the urea decomposition and nitrogen cycling function. Towards the end of the cotton growth period, oxygenation irrigation led to an increase in nitrate nitrogen and ammonium nitrogen content in the soil. The average nitrate nitrogen content in the 0–60 cm soil layer of CO1, CO2, CO3 and CO4 increased by 12.4 %, 14.7 %, 15.9 % and 17.3 % respectively compared with CK. Similarly, the average ammonium nitrogen content of CO1, CO2, CO3 and CO4 in the 0–40 cm soil layer increased by 8.9 %, 11.7 %, 12.0 % and 11.6 % respectively compared with CK. Increasing the dissolved oxygen concentration in irrigation water resulted in elevated dry matter accumulation in cotton. The total dry matter of CO1, CO2, CO3 and CO4 increased by 9.5 %, 12.6 %, 14.6 % and 16.8 % respectively compared with CK. Additionally, the nitrogen concentration in each cotton organ also exhibited an increase. The total nitrogen accumulation of CO1, CO2, CO3 and CO4 increased by 26.1 %, 36.2 %, 48.2 % and 53.1 % respectively compared with CK. Furthermore, increasing the dissolved oxygen concentration in irrigation water also facilitated nitrogen migration to cotton bolls (boll shell + seed + fiber). The cotton boll nitrogen accumulation of CO1, CO2, CO3 and CO4 increased by 1.8 %, 3.4 %, 4.2 % and 4.2 % (absolute value) compared with CK (reached significant level). Finally, the lint yield and fiber quality parameters (micronaire, fiber elongation, fiber breaking strength) exhibited further improvement with the increase in dissolved oxygen concentration in irrigation water. CONCLUSIONS: Increasing the dissolved oxygen concentration in irrigation water promotes nitrogen absorption in cotton, facilitates nitrogen accumulation in cotton bolls, and enhances nitrogen fertilizer utilization efficiency. Moreover, it positively impacts cotton lint yield and fiber quality.

Cotton yield responses to climate change and adaptability of sowing date simulated by AquaCrop model

The feedback mechanism of cotton yield to climate change is important knowledge for cotton planting planning and stable production. However, the impact of sowing date on cotton yield in China's main cotton producing areas under future climate change is still unclear. To deal with it, this study first evaluated the applicability of the AquaCrop model using actual observed cotton growth and yield data. Then, based on the 27 Global Climate Models (GCMs) multi-model ensemble data in the Sixth Coupled Model Intercomparison Project (CMIP6), the future climate changes in China 's main cotton producing areas from 2021 and 2060 (2040 s) and 2061–2100 (2080 s) under two typical Shared Socioeconomic Pathways (SSP) 2–4.5 and SSP5–8.5 were predicted. Finally, the effects of different sowing dates on cotton yield under SSP2–4.5 and SSP5–8.5 scenarios were simulated. The results showed that: (1) AquaCrop model had good applicability and it could accurately simulate cotton growth and yield. (2) The temperature under the SSP2–4.5 and SSP5–8.5 scenarios increased significantly compared with the baseline period (1985–2020). Precipitation during the cotton growth period mainly showed an increasing trend, but the spatial and temporal variability was large. The reference crop evapotranspiration (ETo) during the cotton growth period mainly showed a decreasing trend under the SSP2–4.5 (2040 s) scenario, while it mainly showed an increasing trend in other future periods. (3) The cotton yield under the SSP2–4.5 and SSP5–8.5 scenarios increased by an average of 10.51% and 13.67%, 14.76% and 28.04% in 2040 s and 2080 s compared to the baseline period (1981–2015), respectively. (4) Early sowing was beneficial to increase cotton yield, cotton yield sown on March 31 increased by an average of 5.32% compared to May 10. In conclusion, future climate change will have positive impacts on cotton production in China, and early sowing is an effective adaptation measure to cope with climate change.

Chemical fertilizer reduction combined with organic fertilizer affects the soil microbial community and diversity and yield of cotton.

The soil microbial community plays an important role in modulating cotton soil fertility. However, the effects of chemical fertilizer combined with organic fertilizer on soil chemical properties, microbial community structure, and crop yield and quality in arid areas are still unclear. This study aimed to explore the effects of different organic fertilizers on soil microbial community structure and diversity and cotton growth and yield. High-throughput sequencing was used to study the soil bacteria and fungi in different growth stages of cotton. The field fertilization experiment had five treatments. The results indicated that the treatments of chemical fertilizer reduction combined with organic fertilizer significantly increased soil available nitrogen and phosphorus in cotton field. There were significant differences in the abundance of the bacterial and fungal communities in the dominant phyla among the treatments. At the phyla level, there were not significantly different in the diversity of bacteria and fungi among treatments. There were significant differences in the composition and diversity of bacterial and fungal communities during the entire cotton growth period (p = 0.001). The rhizosphere bacterial and fungal community structure was significantly affected by soil TK, NH4+, AK, TP, AN, and NO3-. The different fertilization treatments strongly influenced the modular structure of the soil bacterial and fungal community co-occurrence network. A reduction in chemical fertilizer combined with organic fertilizer significantly improved cotton stem diameter and seed yield, and the effect of the biological organic fertilizer on plant growth and yield formation was greater than that of ordinary organic fertilizer. This study provide a scientific and technical basis for the establishment of environmentally friendly green fertilization technology for cotton in arid areas and the promotion of sustainable development of cotton industry.

Relay intercropping cover crop combined with reduced nitrogen application improves subsequent cotton agronomic traits while maintaining yield and quality

AbstractApplying cover crops to reduce nitrogen (N) fertilizer application while ensuring crop productivity is a major challenge for sustainable agricultural production. However, few studies have quantified N fertilizer application reduction through the use of February orchid (Orychophragmus violaceus) cover crops with the goal of ensuring cotton productivity. We conducted field experiments in the Yellow River basin on two cropping systems, monoculture cotton (Gossypium hirsutum L) and cotton/February orchid under four levels of N application (0 [N0], 112.5 [N1], 168.75 [N2], and 225 [N3] kg N·ha−1), to evaluate the impacts of cover cropping on cotton growth parameters, yield, and quality under different N application levels. The results indicated that replacing winter fallow with February orchid prolonged the cotton growth period and increased plant height, leaf area index (LAI), and dry matter accumulation but did not improve cotton yield or fiber quality. The Cotton/February orchid system under a 168.75 kg ha−1 N application rate improved cotton growth, and achieved yield and quality equivalent to those of monoculture cotton under a 225 kg ha−1 N application. Further analysis revealed that February orchid cover crop and N application positively affected lint yield, whereas plant height, LAI, and dry matter accumulation (positively) and phenology (negatively) predicted lint yield and fiber quality. In conclusion, cotton relay intercropping with February orchid in combination with 168.75 kg ha−1 N application is recommended as a suitable cropping system to reduce fallow fields and ensuring cotton productivity in the Yellow River basin and other areas with similar ecological conditions.

Accumulation of Na+ in Cotton Field under Mulched Drip Irrigation of Brackish Water in Arid Areas

In arid areas, the disordered accumulation of Na+ in cotton fields under mulched drip irrigation seriously affects the normal growth and development of cotton. To reveal the process and mechanism of Na+ accumulation, in situ field tests were conducted in typical cotton planting bases in the south of Xinjiang, China. Eight experimental scenarios were set up to use brackish and fresh water for drip irrigation under mulch during the whole growth period of cotton according to the drip irrigation system. By monitoring the weather, groundwater level, and soil moisture before and after irrigation, and testing the soil salinity and Na+ concentration, the temporal and spatial distribution and transport characteristics of Na+ were compared and studied. The results showed that: (1) owing to the strong spatial variation of soil permeability, soil water and salt dynamics exhibited significant differences after irrigation in all experimental scenarios in the study area, especially at a depth of 0–60 cm. (2) The Na+ profile exhibited a “thin waist”, whose depth depended on the climate and lithology of the soil; however, this phenomenon was not observed in the salt profile. (3) The accumulation of Na+ in cotton fields is an extremely complex dynamic process that is influenced by both natural and human activities. This process is controlled by the dynamic characteristics of soil water and salt, but it is different from the distribution of soil salt in time and space. This study provides necessary technical support for the formulation of drip irrigation systems under brackish water film, and provides a scientific basis for fine agricultural planting and water resources management in arid areas.

Harvest Aids Applied at Appropriate Time Could Reduce the Damage to Cotton Yield and Fiber Quality

The application of harvest aids is an important prerequisite for the mechanical harvesting of cotton that can effectively reduce the impurity content and improve the picking rate and operating efficiency of machine-picked cotton. However, determining the appropriate spraying time of harvest aids to achieve the synergistic improvement of cotton boll weight and fiber quality is still unclear. In this study, the damage of harvest aids to cotton boll weight and fiber quality as well as its quantitative relationship to cotton boll age were studied through testing different harvest aid compounds and spraying times. The spraying of harvest aids significantly shortened the boll growth period of cotton by 3.60–6.45 d, and concentrated boll opening was beneficial to cotton mechanical harvesting. The boll weight of immature cotton was significantly decreased by 0.63–1.12 g; the fiber strength was significantly decreased by 2.48–2.77 cN·tex−1, and the micronaire value deteriorated. The negative effect on the boll weight and fiber quality was aggravated by the decrease in the ratio of boll age to boll period (Rd/b) during the harvest aid spraying time. When the fiber strength damage was controlled at 1%, the spraying time Rd/b of the harvest aids was 0.77–0.82, and the boll weight loss was also controlled at 5%. Therefore, it is recommended that an Rd/b of 0.77–0.82 be used to balance the contradiction between cotton yield and fiber quality under harvest aid application.

Establishment of a Monitoring Model for the Cotton Leaf Area Index Based on the Canopy Reflectance Spectrum

Cotton is the main economic crop in China and is important owing to its use as an industrial raw material and a cash crop. This experiment was conducted in the main cotton-producing area of Xinjiang, China. A hyperspectrometer was used to monitor the canopy spectral reflectance of cotton at different stages of growth. The results showed that the leaf area index (LAI) increased with the increase in the amount of nitrogen fertilizer added during the early full boll stage and decreased with the increase in nitrogen fertilization in the full and late boll stages. Insufficient or excessive fertilization led to a decrease in the LAI. The visible light band indicated that the canopy spectral reflectance decreased, and the amount of fertilizer increased in all the growth stages. The near-infrared band revealed that the canopy spectral reflectance increased with the amount of nitrogen applied during the bud stage, early boll stage, and the most vigorous period of boll growth. During the flowering period, the spectral reflectance followed the order N3 > N4 > N2 > N1 > N0. During the entire growth period of cotton, the values of the cotton LAI predicted using the ratio vegetation index (RVI) model were found to best fit the measured values. The LAI monitoring models of cotton in each growth stage were different. The TVI model is the best in the bud and early boll stages. The NDVI model is the best in the flowering stage, and the DVI model is the best in the full boll stage. This study provides a basis to accurately monitor the LAI in each growth period of cotton.

Rational biochar application rate for cotton nutrient content, growth, yields, productivity, and economic benefits under film-mulched trickle irrigation

Biochar application to soils has been proven to be an efficient way for yield enhancement in agricultural systems. However, what is the most economical biochar application rate (BCAR) for cotton in saline-alkali soils in arid and semi-arid zones remains unclear. To narrow the gap, this study aims to investigate how biochar application affected the nutrient content, growth, yield, quality, and productivity of cotton, and to find the rational BCAR. The three-year field experiments of biochar application combined with plastic film mulched drip irrigation were conducted for cotton in Xinjiang, China. The biochar was continuously applied to the farmland at 0 (in 2018)+ 0 (in 2019)+ 0 (in 2020), 10 + 10 + 10, NT (no test)+ 25 + 25, 50 + 50 + 30, and 100 + 100 +NT t ha−1 during cotton growth period of 2018–2020. The cotton growth, yield, and quality indicators were observed and used for computing water-fertilizer productivity. The cost-benefit analysis was referred to recommend a rational BCAR. All four biochar application treatments increased the leaf/stem/root nutrient (N, P, and K) content than control during different cotton growth stages. The daily relative content of chlorophyll increased with the increasing BCAR and were larger at biochar treatments of 50 and 100 t ha−1 than 0, 10, and 25 t ha−1. The growth and yield-related indicators (plant height, stem diameter, leaf area index and seed yield), irrigation water productivity, and partial fertilizer (N, P, and K) productivity consistently increased than control under biochar application conditions, and the BCAR of 10 t ha−1 showed the greatest advantages in enhancing germination rates, cotton yields, water-fertilizer productivities, and financial income than biochar treatments of 0, 25, 50 and 100 t ha−1. However, neither cotton fiber quality indices (length, Micronaire, strength or uniformity index) were significantly affected by biochar applications. Based on the economic analysis, the rational BCAR was 10 t ha−1 each year (continued for three years) for cotton planting, which was a best dose that could be applied to arid zones and have not been reported before.

Effects of Biochar Application before and after Freeze-Thaw on Soil Hydrothermal and Cotton Growth under Drip Irrigation

Biochar as an organic soil conditioner has colossal application potential. Many recent studies revealed the influence of biochar on the soil during the crop growth period. However, few studies considered the effect of seasonal freeze-thaw on biochar’s improvement effect. Therefore, we conducted a field experiment to observe the impact of biochar on soil and cotton (Gossypium hirsutum L.). We used four biochar application rates (0.33%, 0.66%, 1.00%, and 1.33% of soil mass fraction) and applied biochar in the cotton field before and after seasonal freeze-thaw, respectively. The results showed that applying biochar after freeze-thaw was more effective on soil water storage and soil temperature preservation during the cotton growth period. Moreover, applying biochar with 0.66% soil mass fraction after freeze-thaw improved the cotton biomass by 5.31~36.13%, leaf area index by −10.82~32.52%, and seed cotton yield by 3.88~21.98%. Based on the principal component analysis of cotton fiber quality, we found that 0.66% biochar application after freeze-thaw improved cotton fiber most significantly. In total, applying biochar at 0.66% soil mass fraction after freeze-thaw was the most optimal application mode for improving soil hydrothermal conditions, cotton growth, and fiber quality. Our study can provide a scientific reference for applying biochar in northern Xinjiang, China.

Modeling the impacts of cover crops and no-tillage on soil health and cotton yield in an irrigated cropping system of the Texas Rolling Plains

An interest to grow cover crops is increasing in the semi-arid Texas Rolling Plains (TRP) region, where cotton ( Gossypium hirsutum L.) is a major cultivated crop. Under conservation tillage systems, cover crops are expected to enhance ecosystem services, including improved soil health and erosion reduction. However, there is a concern that cover crops could deplete soil water content and affect the subsequent cotton production. This study evaluated the efficacy of growing winter cover crops in a continuous cotton production system under irrigated conditions at Chillicothe, TX with the Denitrification Decomposition (DNDC) model. Treatments included: conventional tillage (CT), no-till (NT), no-till with mixed-species cover crop (Mixture), and no-till with winter wheat ( Triticum aestivum ) cover crop (Wheat) . The DNDC model was calibrated and validated against observed data from 2012 to 2020. Seed cotton yield prediction during model calibration had a percent bias (PBIAS) of 4.4 %, root mean square error (RMSE) of 385 kg ha −1 , r 2 of 0.55, d-index of 0.84, and a Nash–Sutcliffe model efficiency (NSE) of 0.92. Seed cotton yield during model validation had PBIAS of − 2.0 %, RMSE of 279 kg ha −1 , r 2 of 0.75, d-index of 0.93, and a NSE of 0.72. Simulated soil organic carbon (SOC) stock had a PBIAS of 8.6 % and 3 %, RMSE of 1.8 and 0.74 Mg ha −1 , r 2 of 0.92 and 0.98, d-index of 0.97 and 0.99, a NSE of 0.89 and 0.98 during model calibration and validation, respectively. Daily trends of simulated soil water content at 0–100 cm depth were within the acceptable range. Long-term simulations (25 years) revealed: (1) planting cover crops could accrue 11–19 % more SOC and 4–14 % more TN compared to no-cover crops, (2) cotton yield under cover crops was not significantly different from that under no-cover crops, (3) cover crop biomass increased immoblisation of nitrogen (N), which led to a decline in available N and hence, N-stress was simulated during the initial cotton growth period. In nutshell, results showed the potential of conservation management systems such as no-till and cover crops in improving soil health indicators without affecting cotton yields. • Simulated effect of mixture and winter wheat cover crops on seed cotton yield was not significant. • Cover crops sequestered 11–19 % more soil organic carbon (SOC) compared to no-cover crops. • Cover crops accrued 4–14 % more total nitrogen (TN) compared to no-cover crops. • Rate of SOC and TN accrual was highest under mixed species cover crop followed by winter wheat. • Soil N availability was declined in early stages of cotton due to increased N immobilization by cover crop biomass.

Analysis of mulched drip irrigation with brackish water in cotton fields using the HYDRUS-3D numerical model

This study combined continuous monitoring in the field using computer modeling to understand soil water movement and salt transport so as to design a suitable irrigation system for cotton using mulched drip irrigation with brackish water. A reasonable irrigation regime was determined and verified using thresholds of water and salinity stress in the various stages of cotton growth. In addition, some key factors, such as emitter discharge rate, emitter spacing, and initial water content, were screened for simulation, and irrigation uniformity and desalination rate were selected as the indicators for evaluation. The results showed that: ( i) The HYDRUS-3D model was a useful tool for designing suitable irrigation regimes, and the determined suitable irrigation quota was 5160 m3 hm−2 under mulched drip irrigation with brackish water during the growth period of cotton in 2019. ( ii) The irrigation uniformity and leaching rate decreased with an increase in the emitter discharge, and the linear relationship between uniformity, leaching rate, and emitter discharge could be identified. ( iii) The irrigation uniformity and leaching rate decreased with an increase in emitter spacing, and power functions might be used to calculate uniformity, leaching rate, and emitter spacing. ( iv) The irrigation uniformity and leaching rate increased with an increase in initial water content, and the relationship between the two indexes and initial water content was defined by a linear function and a power function, respectively. These results provided a valuable reference for the rational use of drip irrigation with brackish water.

Effects of Soil Water Regulation on the Cotton Yield, Fiber Quality and Soil Salt Accumulation under Mulched Drip Irrigation in Southern Xinjiang, China

To optimize suitable water-saving and soil salt-controlling irrigation needed for the high yield and good quality of cotton in southern Xinjiang, a field experiment was carried out to study the effects of soil water lower limits on water consumption, water use efficiency (WUE), yield, cotton fiber quality and soil salt accumulation under mulched drip irrigation in Korla, Xinjiang. The field capacity (FC) was regarded as the upper limit of soil moisture, and five soil water lower limits (85% FC, 75% FC, 65% FC, 55% FC, 45% FC, referred as T1~T5, respectively) were designed during the cotton growth period. The results indicated that the irrigation frequency and irrigation quota of cotton were gradually increased with the increase in the soil water lower limit, while the water consumption modulus for T2 treatment during the critical period of water demand arrived at the maximum value. Moreover, with the decrease in the soil water lower limit, the WUE, fiber micronaire value and fiber maturity index of cotton increased, whereas the yield, nitrogen partial factor productivity (PFPN) and fiber breaking elongation of cotton decreased. However, when the soil water lower limit exceeded 75% FC, the increase had little effect on the cotton yield increase and PFPN improvement, and the yield and PFPN for T2 treatment were 7146.4 kg∙hm−2 and 23.82 kg∙kg−1, respectively, In addition, the decrease in the soil water lower limit was unfavorable for an increase in fiber length, but it was conducive to the enhancement of fiber strength. Furthermore, soil salt accumulated inside and outside the film for the designed soil water lower limits, and the amount of accumulated salt in 0~100 cm followed T3 > T5 > T1 > T2 > T4. Based on a comprehensive analysis with the entropy TOPSIS method, the findings of the present study suggested that the suitable soil water lower limit for cotton under mulched drip irrigation was 75% FC in southern Xinjiang, China.

Fourier transform infrared spectral features of plant biomass components during cotton organ development and their biological implications

BackgroundThe majority of attenuated total reflection Fourier transform infrared (ATR FT-IR) investigations of cotton are focused on the fiber tissue for biological mechanisms and understanding of fiber development and maturity, but rarely on other cotton biomass components. This work examined in detail the ATR FT-IR spectral features of various cotton tissues/organs at reproductive and maturation stages, analyzed and discussed their biological implications.ResultsThe ATR FT-IR spectra of these tissues/organs were analyzed and compared with the focus on the lower wavenumber fingerprinting range. Six outstanding FT-IR bands at 1 730, 1 620, 1 525, 1 235, 1 050 and 895 cm−1 represented the major C=O stretching, protein Amide I, Amide II, the O–H/N–H deformation, the total C–O–C stretching and the β-glycosidic linkage in celluloses, respectively, and impacted differently between these organs with the two growth stages. Furthermore, the band intensity at 1 620, 1 525, 1 235, and 1 050 cm−1 were exclusively and significantly correlated to the levels of protein (Amide I bond), protein (Amide II bond), cellulose, and hemicellulose, respectively, whereas the band at 1 730 cm−1 was negatively correlated with ash content.ConclusionsThe resulting observations indicated the capability of ATR FT-IR spectroscopy for monitoring changes, transportation, and accumulation of the major chemical components in these tissues over the cotton growth period. In other words, this spectral technology could be an effective tool for physiological, biochemical, and morphological research related to cotton biology and development.

Organic Liquid Fertilizer Coupled With Single Application of Chemical Fertilization Improves Growth, Biomass, and Yield Components of Cotton Under Mulch Drip Irrigation.

Excessive fertilization, low nutrient utilization rate, and continuous deterioration of cotton field environment have adversely affected the sustainable development of cotton in Xinjiang province of China. To overcome these issues, we hypothesized that an appropriate combination of liquid organic fertilizer and chemical fertilizer (CF) would effectively reduce the input of CF without sacrificing the quality and yield of cotton. A 2-year field experiment explores the effects of three fertilization treatments on the growth, biomass accumulation, and yield of cotton. The three fertilization treatments, namely, no application of fertilizer (CK), the single application of CF, and the combined application of organic liquid fertilizer and CF (F0.6–F1.4), were set up in five ratios. Compared with CF treatment, the combined application of organic liquid fertilizer and CF treatments (F0.6–F1.2) speeded the growth period of cotton by 2–7 days with increased plant height, stem diameter, functional leaf width, and more number of branches, with 9.7–23.5 and 8.4–28.5% higher total plant biomass (TPB) and reproductive organs biomass (ROB), respectively. Compared with CF treatment, the rapid growth duration and maximum accumulation rate of reproductive organs were the highest in F0.8 treatment, with an average increase of 4.6 days and 20.3%. Increment in biomass accumulation contributed to an average increase of 21.8 and 18.9% in cotton boll number and yield, respectively, under F0.8 treatment. Principal component analysis shows that the total biomass, ROB, and total bolls per unit area were positively correlated with the yield, while stem diameter and vegetative organ biomass are negatively correlated with the yield. In conclusion, under film mulching with drip irrigation, organic liquid fertilizer combined with CF reduced by 20% (F0.8 treatment: N, P2O5, and K2O were 182, 104, and 76 kg hm–2, respectively) can sustain the normal growth, promote the accumulation rate of ROB, and lead to efficient cotton production.

Determining water use and crop coefficients of drip-irrigated cotton in south Xinjiang of China under various irrigation amounts

Crop evapotranspiration (ETc) and crop coefficient (Kc) can vary among various geographical locations and cultivated species. Therefore, determining regional- and species-specific crop coefficients is fundamental for rational irrigation water management. A two-year field study was conducted in south Xinjiang of northwest China to estimate periodic ETc and reference evapotranspiration (ET0), and thus develop the regional crop coefficient (Kc) at various growth stages of fertigated cotton (Gossypium hirstum L. Xinluzhong No 67) under various irrigation amounts. ETc was determined by the soil water balance method, while ET0 was obtained using the FAO (Food and Agriculture Organization of the United Nations) Penman-Monteith model. The results indicated that increasing irrigation amounts resulted in increased seed cotton yields, but reduced crop water productivity (WP). The water consumption at flowering and boll setting stages accounted approximately for 60% of the seasonal water use of cotton under various irrigation amounts. The average locally developed Kc (Kc-local) values over two seasons were 0.38, 1.30 and 1.09 for initial, mid-season, and end-season stages, respectively. The locally developed initial Kc (Kc-local-ini) (0.38) was higher than the optimized initial-stage Kc (Kc-opt-ini) (0.23) and similar to the FAO recommended Kc (Kc-FAO) (0.35). The optimized Kc (Kc-opt) did not significantly differ from Kc-FAO at mid-season and end-season stages. The locally developed middle-stage Kc (Kc-local-mid) was 10% higher than the optimized middle-stage Kc (Kc-opt-mid) and the FAO recommended middle-stage Kc (Kc-FAO-mid), and the locally developed end-stage Kc (Kc-local-end) was approximately 82% higher than the optimized end-stage Kc (Kc-opt-end) and the FAO recommended end-stage Kc (Kc-FAO-end). The difference between Kc-local, Kc-opt and Kc-FAO was attributed to the variations of climate condition, cultivated variety and field management. Kc-local determined by the soil water balance method in the present study fully considered the regional conditions including weather, species and management practices, which can be adopted to guide the irrigation management in this region. This study provided credible cotton periodic Kc in the arid and semiarid regions of northwest China. A second-order polynomial relationship between cotton Kc and t/T (the days after emergence/the days of total cotton growth period) was established, which can provide a reference for the determination of local cotton Kc and irrigation management.

Differentiation and Variability in the Rhizosphere and Endosphere Microbiomes of Healthy and Diseased Cotton (Gossypium sp.).

The plant microbiome is a key determinant of health and productivity. However, it is still difficult to understand the structural composition of the bacterial and fungal microbiomes of diseased and healthy plants, especially the spatial dynamics and phylogenies of endophytic and rhizosphere microbial communities. We studied the differentiation and variability in the rhizosphere and endosphere microbiomes of healthy and diseased cotton from north and south of the Tianshan Mountains using the methods of PCR-based high-throughput sequencing and real-time quantitative PCR. The endophytic and rhizosphere bacterial abundances in the diseased plants were greater than those of healthy plants. The numbers of endophytic and rhizosphere fungi associated with diseased plants were greater than those associated healthy plants (p < 0.05). Endophytic and rhizosphere bacteria did not share common OTUs. The dominant rhizosphere bacteria were Proteobacteria (29.70%), Acidobacteria (23.14%), Gemmatimonadetes (15.17%), Actinobacteria (8.31%), Chloroflexi (7.99%), and Bacteroidetes (5.15%). The dominant rhizosphere fungi were Ascomycota (83.52%), Mortierellomycota (7.67%), Basidiomycota (2.13%), Chytridiomycota (0.39%), and Olpidiomycota (0.08%). The distribution of dominant bacteria in different cotton rhizosphere soils and roots differed, with the dominant bacteria Pseudomonas (15.54%) and Pantoea (9.19%), and the dominant fungi Alternaria (16.15%) and Cephalotrichum (9.10%) being present in the greatest numbers. At sampling points in different ecological regions, the total numbers of cotton endophytic and rhizosphere microbiome OTUs from southern to northern Xinjiang showed an increasing trend. There were significant differences in the composition and diversity of rhizosphere microbes and endophytes during the entire cotton growth period and in representative ecological regions (p < 0.01), whereas rhizosphere microbes and endophytes showed no significant differences among the four growth periods and in representative ecological regions. RB41, H16, Nitrospira, and Sphingomonas play important roles in the microbial ecology of cotton rhizosphere soil. Pseudomonas accounted for a large proportion of the microbes in the cotton rhizosphere soil. This study provides an in-depth understanding of the complex microbial composition and diversity associated with cotton north and south of the Tianshan Mountains.

Microclimatic conditions and seed cotton yield as affected by sowing time, row orientation and plant spacing under Bt cotton hybrid

Microclimatic modifications are the effective and suitable adaptation strategy to minimize the adverse affect of weather on cotton. In this context, multi-location field experiments were laid out at Bathinda and Faridkot, districts of Punjab during Kharif 2018 with Bt-cotton hybrid RCH 773 BGII and sown at three times i.e., April 30, May 15 and May 30 with two row orientations (North-South: N-S and East-West : E-W) and three plant spacing’s (67.5 cm × 45.0 cm, 67.5 cm × 60.0 cm and 67.5 cm × 75.0 cm) in factorial split plot design and replicated by three times. The results revealed that during the morning (0730 IST) and afternoon time (1430 IST), soil and within-canopy temperature were found higher during emergence and mid growth stages with delayed sowing which reduced the crop growing period and resulted the seed cotton yield to be declined with delayed sowing. On the other hand, morning and afternoon within-canopy relative humidity was recorded higher with delayed sowing during sensitive stages of the crop which provided favorable weather for higher infestation of cotton insect-pest and disease and caused reduction in seed cotton yield at both the study locations. Soil temperature and within-canopy temperature were recorded higher in East-West row oriented, while within-canopy RH was higher under North-South row orientation at both the study regions. During entire growth period of cotton, soil temperature and within-canopy temperature recorded during morning and afternoon hours were found to be increased with increase in plant spacing whereas within-canopy relative humidity during morning and afternoon hours was found to be decreased with increase in plant spacing at both the locations. Among microclimatic parameters, higher variation was observed between sowing dates, while lesser variation was recorded among row orientations and plant spacings.

A Cotton High-Efficiency Water-Fertilizer Control System Using Wireless Sensor Network for Precision Agriculture

Scientific researchers have applied newly developed technologies, such as sensors and actuators, to different fields, including environmental monitoring, traffic management, and precision agriculture. Using agricultural technology to assist crop fertilization is an important research innovation that can not only reduce the workload of farmers, but also reduce resource waste and soil pollution. This paper describes the design and development of a water-fertilizer control system based on the soil conductivity threshold. The system uses a low-cost wireless sensor network as a data collection and transmission tool and transmits the data to the decision support system. The decision support system considers the change in soil electrical conductivity (EC) and moisture content to guide the application of water-fertilizer, and then improves the fertilization accuracy of the water-fertilizer control system. In the experiment, the proposed water-fertilizer control system was tested, and it was concluded that, compared with the existing traditional water-fertilizer integration control system, the amount of fertilizer used by the system was reduced by 10.89% on average, and it could save 0.76–0.87 tons of fertilizer throughout the whole growth period of cotton.

A novel cotton mapping index combining Sentinel-1 SAR and Sentinel-2 multispectral imagery

Cotton is an important cash crop in the world, as the main source of natural and renewable fiber for textiles. Accurate and timely monitoring of the cotton distribution is crucial for cotton cultivation management and international trade. However, most of the previous researches on cotton identification using remotely sensed images are highly dependent on training samples, and the collection of samples is time-consuming and expensive. To overcome this limitation, a new index, termed as Cotton Mapping Index (CMI), was developed in this study for automatic cotton mapping using time series of Sentinel-1 synthetic aperture radar (SAR) and Sentinel-2 Multispectral Instrument (MSI) satellite data. Four sites in the United States (U.S.) and four sites in China were selected to develop and assess the performance of the CMI. The spectral characteristics derived from Sentinel-2 and backscattering coefficients derived from Sentinel-1 for cotton and non-cotton crops during the cotton growth period were analyzed. Considering the phenology differences of crops in different regions, the features at an adaptive window were adopted to construct the CMI. The results showed that at the peak greenness period, the multiplication of red-edge 1 and red-edge 2 band for cotton samples were much larger than those for non-cotton samples, whereas the spectral angle at the red band as well as the absolute values of backscattering coefficients in vertical transmit and vertical receive (VV) polarization for cotton samples were much smaller than those for non-cotton samples. Based on these findings, the CMI was developed to identify cotton cultivated area within the cropland area. The overall accuracy of classification results for the sites in the U.S. was higher than 81.20%, and the mean relative error for the sites in Xinjiang of China was 26.69%. The CMI, which incorporated optical and radar features, had a better performance than the indices using optical features solely. The advantage of the CMI over supervised classifiers (i.e., k-nearest neighbors, support vector machine and random forest) is that no training samples are required. Moreover, the cotton distribution map can be obtained before the harvest using the CMI. These results indicated the potential of the CMI for cotton mapping. The applicability of CMI in other regions with different cropping systems and crop types needs to be further assessed in the future study.