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Applying 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. Core Ideas: Replacing winter fallowing of fields with February orchid cultivation improved cotton growth parameters.Improvement in cotton growth and productivity with increasing nitrogen application rates.Relationships among cotton phenology, agronomic traits, yield, and quality were quantified.February orchid combined with 75% N fertilizer ensured cotton biomass and yield. [ABSTRACT FROM AUTHOR]

Determining the optimal plant architecture and canopy structure are important objectives in research on the breeding and cultivation of high-yielding crops. To address this challenge, a field experiment was conducted in Anyang, Henan, China, to assess cotton light interception, boll spatial distribution, leaf area index (LAI), plant height and biomass, lint yield and yield component during 2018–2019. Treatments including 10 cotton cultivars with belong to tower-shaped and tube-type canopy structure. Compared with compact cotton varieties, the loose and tower-shaped cotton varieties intercepted more light (average 28.6%) and had a higher LAI (average 34.2%), resulting in a higher cotton yield (average 14.8%). In addition, polynomial correlation showed that the maximum light interception rate occurred at the flowering and boll-forming stage, when the annual mean plant height (94.6 cm), LAI (3.58) and biomass (15,006 kg ha−1) all reached their peak. Moreover, yield was extremely significantly positively correlated with intercepted photosynthetically active radiation (IPAR) (R = 0.7) and positively correlated with light use efficiency (LUE) (R = 0.36). Overall, the results suggest that cotton cultivars with loose and tower-type canopy structures intercept more light and should be planted to increase cotton yield and LUE in the Yellow River basin of China and areas with similar conditions. [ABSTRACT FROM AUTHOR]

Identifying the ideal plant nature and canopy structure is of great importance for improving photosynthetic production and the potential action of plants. To address this challenge, an investigation was accomplished in 2018 and 2019 at the Institute of Cotton Research (ICR) of the Chinese Academy of Agricultural Science (CAAS), Henan Province, China. Six cotton varieties with diverse maturities and plant canopy structures were used to evaluate the light interception (LI) in cotton, the leaf area index (LAI), the biomass, and the yield throughout the two years of study. The light spatial distribution in the plant canopy was evaluated using a geographic statistical method, following the increasing quantity of radiation intercepted, which was determined using the rules of Simpson. Compared to the cotton plants with a compact structure, varieties with both a loose and tower design captured a comparatively higher amount of light (average 31.3%) and achieved a higher LAI (average 32.4%), eventually achieving a high yield (average 10.1%). Furthermore, the polynomial correlation revealed a positive relationship between the biomass accumulation in the reproductive parts and canopy-accrued light interception (LI), signifying that light interception is critical for the yield development of cotton. Furthermore, when the leaf area index (LAI) was peaked, radiation interception and biomass reached the highest during the boll-forming stage. These findings will provide guidance on the light distribution in cotton cultivars with an ideal plant structure for light capture development, providing an important foundation for researchers to better manage light and canopies. [ABSTRACT FROM AUTHOR]

The current cotton (Gossypium hirsutum L.) fallow farming system causes soil degeneration and cotton yield reduction. Cover cropping is commonly associated with improved soil fertility and crop productivity, while the effect of cover crops on soil quality and cotton productivity remains unclear in the region. Using a monoculture cotton (cotton-fallow) as the control, a field experiment was conducted to verify the impacts of cotton with two cover crops, Orychophragmus violaceus (cotton/O. violaceus) and Vicia villosa (cotton/V. villosa), on soil chemical properties and cotton productivity. The results showed that cotton/O. violaceus increased the soil organic matter (SOM), total nitrogen (TN), and available nitrogen (AN) by 5.77%, 2.03%, and 13.07% compared to cotton-fallow at a 0–100 cm soil depth, respectively. Cotton/O. violaceus developed relatively greater cotton biomass accumulation and higher cotton yield than cotton/V. villosa and cotton-fallow, an immediate cause of which was greater reproductive organ biomass accumulation and a larger number of bolls per unit area. Furthermore, SOM and TN had a significantly positive correlation with cotton biomass and yield. Cotton/O. violaceus were more conducive than cotton/V. villosa and cotton-fallow in the Yellow River basin of China and in other areas with similar requirements. [ABSTRACT FROM AUTHOR]

Roots play an important role in the response to nitrogen stress in cotton. To better understand the molecular and physiological mechanisms underlying the adaptation of cotton roots to nitrogen stress, the responses of genes in roots to nitrogen changes were analysed by RNA sequencing (RNA‐seq), and morphological and physiological indicators were measured for verification. This study revealed that lack of nitrogen stress (LN, 0 mm) and excess nitrogen stress (HN, 8 mm) inhibited root growth. Moderate nitrogen (MN, 4 mm) resulted in the largest values for root length, projected area and volume. Nitrogen stress regulated root growth via two mechanisms. Nitrogen stress decreased root growth by regulating cell wall growth via alterations in the cell wall composition and the expression of cell wall‐related genes. Under LN and HN, the contents of cellular polysaccharide and glucan reached their lowest levels, whereas the contents of lignin and cellulose reached their highest levels. Lower expression of EXPA17, EXLB1 and PME3 as well as higher expression of EXLA1, WAT1, CESA1, CESA3, CAD6, COMT1, SAMS, LAC4 and NAC081 were obtained under nitrogen stress compared to MN, indicating that nitrogen stress increases lignin and cellulose synthesis and promotes root ageing. Nitrogen stress also decreased root growth by affecting the contents and regulation of salicylic acid (SA), jasmonic acid (JA) and abscisic acid (ABA). Nitrogen significantly upregulated the expression of PAD4, ALD1, WRKY70, WAKL10, MYB44, FER, LHY and BHLH112 as well as significantly downregulated that of TGA6, BT1, BT2 and PYL4. The changes in the expression of these genes under nitrogen stress resulted in significant increases in the SA, JA and ABA contents in roots. Our results suggested that nitrogen stress inhibits the growth of the cotton root system by affecting cell wall growth and hormone regulation. These results contribute to our understanding of how nitrogen regulates cotton root growth at the genetic and physiological levels, and they provide a theoretical basis for the efficient utilization of nitrogen resources. [ABSTRACT FROM AUTHOR]

A field experiment was performed to assess the carbon footprint (CF) of four cropping systems to identify the sustainable cropping system. The four cropping systems were cotton monoculture (CM), winter wheat intercropped with cotton (WIC), wheat cropping followed by transplanted cotton (WTC) and direct-seeded cotton after winter wheat harvest (WDC). The CF calculated per unit area (CFa), yield (CFy), biomass (CFb) and economic output (CFe) increased in the order CM < WIC < WTC < WDC in the low-fertility plot and WIC < WTC < WDC < CM in the high-fertility plot. The results indicated that CM was the best cropping system in the low-fertility plot and presented CFa, CFy, CFb and CFe values of 4848.14 kg CO2eq ha−1 a−1, 0.41 kg CO2eq kg−1 a−1, 0.17 kg CO2eq kg−1 a−1 and 0.06 kg CO2eq ¥ a−1, respectively, whereas WIC was the cropping system with the lowest CFs in the high-fertility plot and presented CFa, CFy, CFb and CFe values of 14,410.70 kg CO2eq ha−1 a−1, 1.31 kg CO2eq kg−1a−1, 0.53 kg CO2eq kg−1 a−1 and 0.34 kg CO2eq ¥−1a−1, respectively. Thus, it can be concluded that improving cropping systems provides a good option for reducing CF and consequently mitigating climate change. Abbreviations: GHG: greenhouse gas; LCA: life cycle assessment; CF: carbon footprint; CFa: The CF calculated per unit area; CFy: The CF calculated per yield; CFb: The CF calculated biomass; CFe: The CF calculated per unit economic output; CM: cotton monoculture cropping system; WIC: wheat intercropped with cotton cropping; WTC: wheat cropping followed by transplanted cotton; WDC: direct-seeded cotton after wheat cropping; IPCC: Intergovernmental Panel on Climate Change; CO2eq: CO2 equivalent; SOC: soil organic carbon; PAS: publicly available specification [ABSTRACT FROM AUTHOR]

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The root system plays an important role in the growth and development of cotton, and root growth is closely related to shoot growth, both of which are affected by N availability in the soil. However, it is unknown how N affects root growth and the root–shoot relationship under various N rates in the Yellow River Basin, China. Thus, the aim of this study was to assess the impacts of the application rate of N on root growth and the root–shoot relationship, to provide insight into the N regulation of root and shoot growth and N efficiency from the perspective of the root system. A field experiment conducted in 2014 and 2015 was used to determine the effects of N rates (0, 120, 240, and 480 kg ha–1) on root morphology, root distribution, the root–shoot relationship, and cotton yield. A moderate N fertilization rate (240 kg ha–1) increased root length, root surface area, and root biomass in most soil layers and significantly increased total root growth and total root biomass by more than 36.06% compared to the 0 kg ha–1 treatment. In addition, roots in the surface soil layers were more strongly affected by N fertilization than roots distributed in the deeper soil layers. Total root length, total root surface area, and root biomass in the 0–15 cm layer were significantly correlated with shoot biomass and boll biomass. In the 60–75 cm layer, total root length, total root surface area, and root length were significantly positively correlated with seed cotton yield. The application of a moderate level of N markedly increased total shoot biomass, boll biomass, and seed cotton yield. Our results show that increased shoot and boll biomasses were correlated with a significant increase in the root system especially the shallow roots in the moderate N treatment (240 kg ha–1), leading to an increase in cotton seed yield. [ABSTRACT FROM AUTHOR]

The cotton-wheat double-cropping system is widely used in the Yellow River Valley of China, but whether and how different planting patterns within cotton-wheat double-cropping systems impact heat and light use efficiency have not been well documented. A field experiment investigated the effects of the cropping system on crop productivity and the capture and use efficiency of heat and light in two fields differing in soil fertility. Three planting patterns, namely cotton intercropped with wheat (CIW), cotton directly seeded after wheat (CDW), and cotton transplanted after wheat (CTW), as well as one cotton monoculture (CM) system were used. Cotton-wheat double cropping significantly increased crop productivity and land equivalent ratios relative to the CM system in both fields. As a result of increased growing degree days (GDD), intercepted photosynthetically active radiation (IPAR), and photothermal product (PTP), the capture of light and heat in the double-cropping systems was compared with that in the CM system in both fields. With improved resource capture, the double-cropping systems exhibited a higher light and heat use efficiency according to thermal product efficiency, solar energy use efficiency (Eu), radiation use efficiency (RUE), and PTP use efficiency (PTPU). The cotton lint yield and biomass were not significantly correlated with RUE across cropping patterns, indicating that RUE does not limit cotton production. Among the double-cropping treatments, CDW had the lowest GDD, IPAR, and PTP values but the highest heat and light resource use efficiency and highest overall resource use efficiency. This good performance was even more obvious in the high-fertility field. Therefore, we encourage the expanded use of CDW in the Yellow River Valley, especially in fields with high fertility, given the high productivity and resource use efficiency of this system. Moreover, the use of agronomic practices involving a reasonably close planting density, optimized irrigation and nutrient supply, and the application of new short-season varieties of cotton or wheat can potentially enhance CDW crop yields and productivity. [ABSTRACT FROM AUTHOR]

The growth and development of cotton are closely related to climatic variables such as temperature and solar radiation. Adjusting planting density is one of the most effective measures for maximizing cotton yield under certain climatic conditions. The objectives of this study were (1) to determine the optimum planting density and the corresponding leaf area index (LAI) and yield under the climatic conditions of Henan Province, China, and (2) to learn how climatic conditions influence cotton growth, yield, and yield components. A three-year (2013–2015) field experiment was conducted in Anyang, Henan Province, using cultivar SCRC28 across six planting density treatments: 15,000, 33,000, 51,000, 69,000, 87,000, and 105,000 plants ha−1. The data showed that the yield attributes, including seed cotton yield, lint yield, dry matter accumulation, and the LAI, increased as planting density increased. Consequently, the treatment of the maximum density with 105,000 plants ha-1 was the highest-yielding over three years, with the LAIs averaged across the three years being 0.37 at the bud stage, 2.36 at the flower and boll-forming stage, and 1.37 at the boll-opening stage. Furthermore, the correlation between the cotton yield attributes and meteorological conditions indicated that light interception (LI) and the diurnal temperature range were the climatic factors that most strongly influenced cotton seed yield. Moreover, the influence of the number of growing degree days (GDD) on cotton was different at different growth stages. These observations will be useful for determining best management practices for cotton production under the climatic conditions of Henan Province, China. [ABSTRACT FROM AUTHOR]

Different cotton (Gossypium hirsutum L.)-wheat (Triticum aestivum) planting patterns are widely applied in the Yellow River Valley of China, and crop yield mainly depends on light interception. However, little information is available on how cotton canopy light capturing and yield distribution are affected by planting patterns. Hence, field experiments were conducted in 2016 and 2017 to study the response of cotton canopy light interception, square and boll distribution, the leaf area index (LAI) and biomass accumulation to three planting patterns: a cotton monoculture (CM, planted on 15 May) system, a cotton/wheat relay intercropping (CWI, planted on 15 May) system, in which three rows of wheat rows were intercropped with one row of cotton, and a system in which cotton was directly seeded after wheat (CWD, planted on 15 June). The following results were obtained: 1) greater light capture capacity was observed for cotton plants in the CM and CWI compared with the CWD, and the light interception of the CM was 22.4% and 51.4% greater than that of the CWI and CWD, respectively, at 30 days after sowing (DAS) in 2016; 2) more bolls occurred at the first sympodial position (SP) than at other SPs for plants in the CM; 3) based on the LAI and biomass accumulation, the cotton growth rate was the greatest in CWD, followed by CM and CWI; and 4) the CM produced significantly greater yields than did the other two treatments because it yielded more bolls and greater boll weight. Information on the characteristics of cotton growth and development in response to different planting patterns would be helpful for understanding the response of cotton yields to planting patterns and would facilitate the improvement of cotton productivity. [ABSTRACT FROM AUTHOR]

Cotton root growth can be affected by different nitrogen fertilizer rates. The objective of the present study was to quantify the effects of nitrogen fertilization rate on cotton root growth and distribution using minirhizotron and soil coring methods. A secondary objective was to evaluate the minirhizotron method as a tool for determining nitrogen application rates using the root distribution as an index. This study was conducted on a Bt cotton cultivar (Jimian 958) under four nitrogen fertilization rates, i.e., 0, 120, 240 and 480 kg ha-1 (control, low, moderate and high levels, respectively), in the Yellow River basin of China from 2013–2015. The sampling process, details of each method as well as the root morphology and root distribution were measured. The operational processes, time and labor needed for the soil core method were all greater than those for the minirhizotron method. The total root length density and the length density in most soil layers, especially in the upper soil layers, first increased but then decreased as nitrogen fertilization increased, and the same trend was observed for both methods. Compared with N0, the total root length density under moderate nitrogen fertilization by the soil coring method increased by more than 94.82%, in 2014 and 61.11% in 2015; while by the minirhizotron method the corresponding values were 28.24% in 2014 and 57.47%, in 2015. Most roots were distributed in the shallow soil layers (0–60 cm) in each method. However, the root distribution with the soil coring method (>73.11%) was greater than that with the minirhizotron method (>47.07%). The correlations between the root morphology indexes of shallow soil depth measured using the two methods were generally significant, with correlative coefficients greater than 0.334. We concluded that the minirhizotron method could be used for cotton root analysis and most cotton roots distributed in upper soil layers (0-60cm). In addition, a moderate nitrogen rate (240 kg ha-1) could increase root growth, especially in the shallow soil layers. The differences observed with the minirhizotron method were clearer than those observed with the soil coring method. [ABSTRACT FROM AUTHOR]

Wheat-cotton double cropping has improved crop productivity and economic benefits per unit land area in many countries, including China. However, relay intercropping of full-season cotton and wheat, the most commonly adopted mode, is labor-intensive and unconducive to mechanization. The direct sowing of short-season cotton after wheat (CAW) has been successful, but cotton yields and economic benefits are greatly reduced. Whether the relay intercropping of short-season cotton before the wheat harvest increases cotton yields remains unclear, as does the earliness and fiber quality relative to those for CAW. Therefore, we directly planted short-season cotton after wheat harvest on 15 June (CAW) as the control and interplanted short-season cotton in wheat on 15 May (S1), 25 May (S2) and 5 June (S3), which were 30, 20 and 10 days prior to wheat harvest, respectively, from 2016 to 2018. The crop growth, yield, yield components, boll distribution, and earliness of the cotton were evaluated. The yields and earliness of short-season cotton under relay intercropping were 26.7–30.6% and 20.4–42.9% higher than those under CAW, respectively. Compared with CAW, relay intercropping treatments increased the boll density, boll weight and lint percentage by 5.6–13.1%, 12.5–24.5% and 5.8–12.7%, respectively. The dry matter accumulation and harvest index under the relay intercropping treatments were also greater than those under CAW, which might be attributed to the greater partitioning of dry matter to the seed cotton than to the boll shells. Among the relay intercropping treatments (S1, S2 and S3), the lint yield did not differ, but S1 and S2 were considerably better than S3 based on earliness and fiber quality. The analysis of the within-plant spatial boll distribution showed that more bolls were formed on the lower to middle fruiting branches and at the first fruiting sites for S1 and S2 than for S3 and CAW. Therefore, the increased earliness and fiber quality induced through early relay intercropping (S1 and S2) could be attributed to an improved spatial boll distribution compared to late relay intercropping (S3) or CAW. Conclusively, compared to late relay intercropping and CAW, early relay intercropping considerably increased the lint yield, fiber quality, and earliness by improving the yield components, boll distribution, and dry matter accumulation and partitioning. The relay intercropping of short-season cotton 20 to 30 days before wheat harvest represents a promising alternative to CAW in wheat-cotton double-cropping systems in the Yellow River Basin of China and other regions with similar conditions. [ABSTRACT FROM AUTHOR]

The photosynthetically active radiation (PAR) of crop canopy is highly related to yield formation, but how it relates to yield and yield distribution is not well understood. The focus of this study was to explore the relationship between light competition under different densities and yield distributions of cotton. The experiment was conducted in 2019 and 2020 at the Cotton Research Institute of the Chinese Academy of Agricultural Sciences in Anyang city, Henan Province, China. A randomized block design was employed, with a total of three repeats. Each repeat had six density treatments: D1: 15,000; D2: 33,000; D3: 51,000; D4: 69,000; D5: 87,000; and D6: 105,000 plants·ha−1. As predicted, the results showed that the canopy light interception, leaf area index, plant height, and biomass of high-density cotton were higher than those of low-density cotton. The aboveground biomass produced by D6 was the highest, and was 12.9, 19.5, 25.4, 46.3, and 69.2% higher in 2019 and 14.3, 19.9, 32.5, 53.7, and 109.9% higher in 2020 than D5, D4, D3, D2, and D1, respectively. Leaf area, plant height, biomass, boll number, and boll weight were significantly correlated with the light interception rate. D5 (87,000 plants·ha−1) had a higher light interception rate and the highest yield. The highest lint yields produced by D5 were 1673.5 and 1375.4 kg·ha−1 in two years, and was 3.2, 4.3, 5.6, 9.7, and 24.7% higher in 2019, and 6.8, 10.6, 13.5, 21.5, and 34.4% higher in 2020 than D6, D4, D3, D2, and D1, respectively. The boll retention of the lower fruit branch under D5 reached 0.51 and 0.57 in two years, respectively. The shedding rate of the upper fruit branch decreased with the increase in cotton density in two years. The boll retention rate and shedding rate in the lower part of cotton plants were most closely related to light interception, with R2 values of 0.91 and 0.96, respectively. Our study shows cotton yield could be improved through higher light interception by optimizing planting density and canopy structure. [ABSTRACT FROM AUTHOR]

Poor grain filling of inferior kernel of summer maize is a major challenge restricting grain yield of summer maize, especially under higher plant densities. Much work so far has proved that tillage practices could regulate soil properties and grain yield of maize effectively. In order to explore the effect of tillage practice on grain filling of inferior kernel of summer maize, field experiments were conducted over two consecutive years (2016–2017), and three tillage practices (T1, no tillage; T2, no tillage with subsoiling; T3, deep horizontal rotary tillage) were assessed. The grain filling parameter showed that final grain weight (A), the time reaching the maximum grain filling rate (T max), the dry matter accumulation under the maximum grain filling rate (W max), the mean grain filling rate (G mean), and the active grain filling period (D) of T2 were usually higher than that of T1 and T3, and significant difference was observed between T2 and T1. Compared with T1, T2 and T3 reduced the soil bulk density and increased the soil porosity, and significantly increased the root dry matter accumulation in the 0–40 cm soil profile by 13.4% and 28.7%, respectively. Soil water content decreased among tillage practices in the order T2 > T1 > T3. However, T2 and T3 increased the water consumption, compared to that of T1. Moreover, T2 and T3 increased post-anthesis photosynthetic capacity, including the photosynthetic rate, leaf area duration, and chlorophyll content, and further improved the post-antheisis and total dry matter accumulation. The enzyme activities of SuSase, StSase, and ADPG-PPase of inferior and superior kernel in T2 and T3 were also higher than that of T1. In conclusion, the present results indicate that subsoiling could promote the grain filling of inferior kernel of summer maize by regulating soil water content, soil water consumption, and photosynthetic capacity. • Tillage practices affected the grain filling of inferior kernel of summer maize. • Subsoiling significantly improved the soil water content in maize production. • Subsoiling or deep horizontal rotary tillage increased post-anthesis photosynthate capacity. • Subsoiling is an optimal tillage practice in promoting the grain filling of inferior kernel of summer maize. [ABSTRACT FROM AUTHOR]

Modification of the cotton canopy results in shade avoidance and competition for light, which shows that density and spatial arrangement of cotton have a great impact on light interception. This experiment was conducted in 2018 and 2019 in the experimental field at the Institute of Cotton Research of Chinese Academy of Agricultural Science in Anyang city, Henan Province, China. Six plant densities of cotton variety SCRC28 were used to assess spatial competition for light in cotton populations during the whole growing period. Light interception data were collected and analyzed according to the spatial grid method and the extension of Simpson's 3/8 rule. The results showed that at the bottom of the canopy, greater light interception was observed at high densities than at low densities, while in the external part of the layer of the canopy in the horizontal direction, low light interception was recorded at low densities. Leaf area, aboveground biomass and plant height were obviously correlated with light interception, and the cotton population with a higher density (8.7 plants m−2) performed best at the light interception competition, and with the highest yield. The results will provide guidance on light management through the optimization of the structure of the canopy to provide more solar radiation and a significant basis by which to improve the management of light and canopy architecture. [ABSTRACT FROM AUTHOR]

The number of cotton plants grown per unit area has recently gained attention due to technology expense, high input, and seed cost. Yield consistency across a series of plant populations is an attractive cost-saving option. Field experiments were conducted to compare biomass accumulation, fiber quality, leaf area index, yield and yield components of cotton planted at various densities (D1, 1.5; D2, 3.3; D3, 5.1; D4, 6.9; D5, 8.7; and D6, 10.5 plants m−2). High planting density (D5) produced 21% and 28% more lint yield as compared to low planting density (D1) during both years, respectively. The highest seed cotton yield (4662 kg/ha) and lint yield (1763 kg/ha) were produced by high plant density (D5) while the further increase in the plant population (D6) decreased the yield. The increase in yield of D5 was due to more biomass accumulation in reproductive organs as compared to other treatments. The highest average (19.2 VA gm m−2 d−1) and maximum (21.8 VM gm m−2 d−1) rates of biomass were accumulated in reproductive structures. High boll load per leaf area and leaf area index were observed in high planting density as compared to low, while high dry matter partitioning was recorded in the lowest planting density as compared to other treatments. Plants with low density had 5% greater fiber length as compared to the highest plant density, while the fiber strength and micronaire value were 10% and 15% greater than the lowest plant density. Conclusively, plant density of 8.7 plants m−2 is a promising option for enhanced yield, biomass, and uniform fiber quality of cotton. [ABSTRACT FROM AUTHOR]

The number of cotton plants grown per unit of ground area has gained attention due to the high prices of inputs and lower production. Cotton yield per unit of area in Henan province has been stagnant in the last few years. The objectives of this study were to investigate cotton growth, yield, boll spatial distribution and biomass accumulation using different plant densities at cultivation and to find out the optimal plant density. A 2-year field experiment was conducted in a randomized complete block design under six plant densities (D1, 15,000; D2, 33,000; D3, 51,000; D4, 69,000; D5, 87,000 and D6, 105,000 ha−1). Cotton grown at lower plant density produced taller plants and high number of leaves per plant while greater number of branches, fruiting nodes and high number of bolls per unit of ground area were produced under high plant density. Boll retention rate decreased as plant population increased and at nodes 1–8 the rate decreased slowly and then increased dramatically. The highest seed cotton yield (4546 kg ha−1) and lint yield (1682 kg ha−1) was produced by D5. The seed cotton and lint yield produced by D5 were 51–55%, 40–37%, 22–26%, 11–15%, 12–15%, 28–30%, 21–24%, 15–20%, 7–13% and 13–17% higher than D1, D2, D3, D4 and D6 during both years of experimentation, respectively. The increase in seed yield was due to higher biomass accumulation in reproductive organs under D5 plant density. The highest average (110.4 VA kg ha−1 d−1) and maximum (126 VM kg ha−1 d−1) rate of reproductive organs biomass was also accumulated by D5 as compared to other plant densities. The results suggest that D5 is the optimal plant density for high reproductive biomass accumulation and high yield for the area of Henan province. [ABSTRACT FROM AUTHOR]

The objective of this study was to assess the impacts of nitrogen on the physiological characteristics of the source–sink system of upper fruiting branches under various amounts of nitrogen fertilization. A two-year field experiment was conducted with a Bt cotton cultivar in the Yellow River Basin of China. The growth and yield of cotton of the upper fruiting branches were compared under four nitrogen levels: Control (N0, 0 kg ha−1), low nitrogen (N1, 120 kg ha−1), moderate nitrogen (N2, 240 kg ha−1), and high nitrogen (N3, 480 kg ha−1). The results indicated that in the subtending leaves in upper fruiting branches, chlorophyll content, protein content, and peroxidase (POD) activity dramatically increased with nitrogen application, reaching the highest under the moderate nitrogen treatment. The physiological characters in the seeds had the same trends as in the subtending leaves. Furthermore, the moderate nitrogen rate (240 kg ha−1) had a favorable yield and quality. Our results supported that a moderate nitrogen rate (240 kg ha−1) could coordinate the source–sink growth of cotton in the late stage, enhance the yield and fiber quality, and decrease the cost of fertilizer in the Yellow River Basin of China and other similar ecological areas. [ABSTRACT FROM AUTHOR]

Regulation of plant population density is crucial for optimizing cotton fiber quality. However, the relationship between plant density and fiber quality stability under contrasting climatic conditions remains unclear, and the compromise between fiber quality and temporal stability is unknown. In this study, based on a long-term field experiment with various plant densities (1.5–10.5 plants m–2) conducted from 2008 to 2021, cotton fiber quality variability, including fiber length, fiber strength, elongation, uniformity index, and micronaire, and their temporal stability, were evaluated. We determined the optimal plant density for cotton cultivation and elucidated the contributions of plant density and climatic conditions to the variability of cotton fiber quality and its temporal stability in China's Yellow River Valley. The results revealed that cotton maintained its upper-intermediate quality throughout the study period, with fiber length, strength, elongation, uniformity index, and micronaire values ranging between 28.04 and 30.03 mm, 26.15–30.05 cN tex–1, 5.90–6.83%, 83.85–85.44%, and 4.24–5.14, respectively. An increase in plant density improved fiber quality but impaired temporal stability (P < 0.01), and slight increases in stability at lower plant densities resulted in substantially decreased probabilities of years with major declines in fiber quality class. Plant density and climatic conditions regulated the quality traits (23.5% and 69.3% of the explained variance, respectively), including fiber length, fiber strength, and micronaire, while climate was the most important factor (75.9% of the explained variance) in determining their temporal stability. Photosynthetically active radiation and maximum and mean temperature exhibited significant positive effects on fiber quality, whereas mean diurnal temperature range had the opposite effect. A plant density of 3.3–5.1 plants m–2 ensures the highest temporal stability of cotton fiber quality without declines in the fiber quality class. This study first provides insights into balancing cotton fiber quality and temporal stability through agronomic interventions, with implications for the quantitative prediction of future crop quality changes owing to climatic variation. • Plant density and weather changes explain 23.5% and 69.3% of fiber quality variance. • Temporal stability of fiber quality was primarily affected by climatic variation. • Plant density had the opposite effect on fiber quality and temporal stability. • Small increases in stability reduced the probability of fiber quality decline. [ABSTRACT FROM AUTHOR]

Non-film drip irrigation cotton planting mode can effectively solve the problem of residual film pollution in arid areas and promote sustainable agricultural development. However, the research on the efficient irrigation regime and soil hydrothermal microenvironment suitable for non-film drip irrigation cotton planting is scarce. Considering this, using the data monitoring technology based on internet of things sensors, we set 3 different irrigation treatments in 2020–2021. In the flowering and boll setting stage, cotton was watered for 4 times (W4), 6 times (W6), and 8 times (W8) with a single irrigation amount of 69 mm for each of these 3 treatments, and the last time irrigation amount under W8 treatment was 52.2 mm. At the seedling stage, the cotton was not irrigated under each treatment. At the squaring stage, the irrigation times and single irrigation amount were the same under each treatment. The results showed that the average soil water content (SWC) in the 50–110 cm soil layer was increased obviously with the increase in the total irrigation amount. Compared with W4 and W8 treatments, W6 treatment exhibited the highest the soil temperature in the 10–30 cm soil layer in the full boll stage and boll opening stage and the highest soil effective accumulated temperature (SEAT) from initial flowering stage to boll opening stage. The reproductive organ allocation rate in two years was 3.6 % and 2 % higher under W6 than under W8, respectively. With the increase of total irrigation amount, the cotton yield was increased, but the irrigation water use efficiency (IWUE) was decreased. The highest cotton yield was achieved under W8 treatment, but it was not significantly different from that under W6 treatment, while IWUE was significantly lower under W8 than under W6. The effective air temperature (EAT) had the greatest positive impact on the average effective soil temperature (EST) in 10–50 cm soil layer, while the cumulative irrigation amount (CIA) had a negative impact on average EST in 10–50 cm soil layer. Evapotranspiration (ET) and SEAT were positively correlated with biomass accumulation amount and lint yield. In summary, the irrigation regimes of 2 times of irrigation at the squaring stage with a single irrigation amount of 45 mm and 6 times of irrigation at the flowering and boll setting stage with a single irrigation amount of 69 mm can be applied to the non-film cotton cultivation mode in southern Xinjiang. Our findings provide a reference for the application of agricultural internet of things technology in soil hydrothermal microenvironment of non-film cotton fields in Xinjiang. • Using spatial grid method to deploy sensors and continuously monitor data. • Revealed changes in soil hydrothermal conditions in non-mulched cotton fields. • The ridge regression model can effectively explain changes in soil temperature. • The irrigation amount has a negative impact on the soil temperature. • The study provides a reference for setting up a non-film cotton irrigation system. [ABSTRACT FROM AUTHOR]

Global warming leads to further shortage of agricultural water resources. Understanding the water consuming characteristics of different cotton cultivars is crucial for efficient utilization of water resources and yield increasing. However, there is little evidence about the effects of cotton cultivars with different plant-type structures on yield formation and temporal and spatial distribution of water consumption. A two-year experiment was conducted at the Cotton Research Institute of the Chinese Academy of Agricultural Sciences in 2020 and 2021 to evaluate the water consumption of six cotton cultivars with different plant-type structures cotton using spatial grid method and water balance method combined with 5TE sensor. The leaf area index (LAI), biomass, yield and spatial distribution of bolls were also measured and analyzed. The results showed that the loose-type cultivars consumed more soil water than the compact-type cultivars, which was due to the higher water consumption in the 40–120 cm soil layer. The cumulative water consumption and water consumption of each soil layer (0–40 cm 40–80 cm and 80–120 cm) of different cotton cultivars had significant quadratic function relationship with LAI, and had significant linear positive correlation with biomass accumulation (aboveground biomass and underground biomass), with R2 greater than 0.8. When consuming the same amount of water, loose-type cultivars produced more biomass and larger green leaf area than compact-type cultivars. However, the yield-increasing and water-saving effects of the two plant-type structure cotton cultivars were similar, while SCRC 28 and Ji 228 have higher yield and water use efficiency (WUE), which were suitable to be popularized and planted in the cotton area of the Yellow River basin. Cotton yield was significantly negatively correlated with boll setting rate in upper canopy and water consumption in 0–40 cm soil layer, and the R respectively were − 0.82 and − 0.69; it was positively correlated with boll setting rate in lower canopy and water consumption in 80–120 cm soil layer, and the R respectively were 0.75 and 0.64. Therefore, increasing the WUE of 0–40 cm soil layer and water consumption in 80–120 cm soil layer was beneficial to high yield of cotton. By optimizing the structure of different plant types, the temporal and spatial distribution of water consumption of cotton can be adjusted, and the yield of cotton can be effectively improved. The results can provide a basis for cotton cultivar selection and precision irrigation management. • Monitoring soil moisture in cotton field with high spatial and temporal resolution. • loose-type cultivars consumed more soil water than the compact-type cultivars, which was due to the higher water consumption in the 40–120 cm soil layer. • Cotton yield exhibits a significant positive correlation with the water consumption of lower soil (80–120 cm). • Loose-type cultivars SCRC 28 and Ji 228 have higher yield and water use efficiency. [ABSTRACT FROM AUTHOR]

Temperature changes and cultivar shifts (cultivar renewal or cultivar replacement) seriously affect cotton phenology and production under climate change but the specific effects remain uncertain. Here, we combined cotton phenological observation data and corresponding meteorological data for approximately twenty years from 56 sites to explore the effect of cultivar shifts on cotton phenology across China. Phenological growth models were used to investigate how these factors influenced cotton phenology in the Yellow River basin, Yangtze River basin and Northwest inland three major cotton regions in China. As a result, the duration of the whole cotton growing period (GPw) was prolonged at 87.5% of stations, although the mean temperature (T mean) during GPw increased at 98.2% of stations. We demonstrated that once the cultivar effect was fixed, the increase in temperature alone produced a general advancement regarding the dates of emergence, squaring, flowering, boll opening and harvesting, leading to a shortening of the corresponding growth period of cotton by 1.74, 2.2, 1.74 and 2.31 days/decade, respectively, and a shortened duration of the whole growth period (GPw) by 4.06 days/decade. In contrast, cultivar shifts prolonged the duration of emergence-squaring, boll opening-harvest and GPw at 32 (57.1%), 46 (82.1%), and 33 (58.9%) stations by an average of 5.13, 11.61 and 6.29 days/decade, respectively, although the durations of the squaring-flowering and flowering-boll opening periods were reduced. However, the difference was that cultivar shifts reduced the length of the GPw of cotton in the Yellow River basin by 1.35 days/decade. This result indicated that, differences in the effect of cultivar shifts on cotton phenology in different cotton regions. Over the last decades, the introduction of new varieties requiring longer heat times in the Yangtze River basin and the Northwest inland cotton region compensated for some of the cotton phenological changes caused by increased temperatures, while early maturing and resistant cotton varieties were more suitable for selection in the Yellow River basin. • Differences in the effect of cultivar shifts on cotton phenology in different cotton regions. • Improved cultivars can partially be compensated for the increased temperature effect on cotton phenology. • Cultivar shifts prolonged the whole growth period of cotton by an average of 6.29 days/decade. • Cultivars with shorter growth periods appear to be a better option for the Yellow River basin. [ABSTRACT FROM AUTHOR]

The advantages of cover crops in enhancing soil organic C (SOC) sequestration and curbing reactive N losses have been verified. However, there is still a lack of related research evaluating the effects of cover crops and N fertilization on soil properties and crop performance as well as their potential relationships, especially in the continuous cotton cropland of the Yellow River Basin. Herein, we examined the impacts of two cropping systems (cotton (Gossypium hirsutum L.)-cotton (C-C) continuous cropping and Orychophragmus violaceus (O. violaceus)/cotton (O/C) relay intercropping) and four N application rates (0 (N0), 112.5 (N1), 168.75 (N2), and 225 (N3) kg N ha−1) on soil chemical properties, cotton yield, biomass, N uptake and N use efficiency (NUE) during 2017–2019 in the Yellow River Basin. In addition, we determined important soil chemical properties and revealed the relationship between soil parameters and lint yield. Compared with the C-C system, the O/C relay intercropping system significantly improved the soil total N (STN), soil organic N (SON), microbial biomass N (MBN), lint yield (1312.84 kg ha−1), biomass (10130.04 kg ha−1) and N uptake (195.68 kg ha−1) by 2%, 2%, 8%, 6%, 7% and 7%, respectively. N application notably increased the soil chemical properties associated with C and N, lint yield, biomass and N uptake, while the NUE of N3 was significantly lower than that of N2. Moreover, the key driving factors that significantly influenced the lint cotton yield were particulate organic N (PON), dissolved organic N (DON), soil ammonia N (SAN), SON, SOC and soil nitrate N (SNN). DON, PON, and SOC were key factors that directly impacted lint yield. According to the Z score of soil parameters, cotton productivity and resource use efficiency, the combination of O/C relay intercropping and N2 yielded the highest total Z score (10.97). Our results demonstrated that O. violaceus /cotton relay intercropping with 75% N application (168.75 kg N ha−1) can maintain higher lint cotton yield, biomass accumulation, N uptake and NUE by increasing soil C and N fractions. Because non-legume crop straw requires a long period of time to decompose, it is necessary to evaluate the legacy impacts of O. violaceus cover cops in long-term experiments in the future. [Display omitted] • O. violaceus /cotton (O/C) relay intercropping increased soil total N, organic N and microbial biomass N. • N fertilization increased soil organic C and each N fraction measured. • Change in soil organic C, particulate organic N and dissolved organic N directly drove the change in cotton yield. • The combination of O/C and 168.75 kg N ha−1 resulted in the highest score in soil chemical properties and cotton productivity. [ABSTRACT FROM AUTHOR]

Many studies have examined the role of mean climate change in agriculture. However, the impact of interannual climate change in different regions on crop yields remains poorly understood. Here, this study combined historical climate and yield data to quantitatively analyze the effects of climate variation on cotton (Gossypium hirsutum L.) yield variability in major cotton-growing areas of China. Climate variation accounted for 54.42%, 58.10%, and 50% of the cotton yield variability in the Yellow River basin (YER), Yangtze River basin (YAR) and northwest inland (NOI), respectively. The combined effect of the three climate variables increased the cotton yields by 9.51% in the YER but decreased the yields by 6.77% and 0.45% in the YAR and NOI, respectively. In addition, the cotton yield increased mainly because the average temperature increased and the solar radiation decreased in the YER, with values of 2.82% and 5.56%, respectively. Rainfall was the main driver of the cotton yield in the YAR, and the increased rainfall reduced the cotton yield by 3.92%. In the NOI, increased solar radiation reduced the cotton yield by 3.47%. Yield variation at the provincial scale was mainly generated by complex models. Moreover, cotton yields showed nonlinear changes in most provinces, and the yield greatly fluctuated in the NOI. The study uniquely illustrates the impact of climatic variation on cotton yield variability in China and further identifies the main driving factors affecting yield variability, with the aim of formulating effective agricultural cultivation management strategies to buffer future crop production from the effects of climate change and to improve cotton production. • Quantitatively evaluate the effects of climate variation on cotton yield variability. • Uniquely illustrates spatial patterns in the relationship between climate variability and cotton yield variability. • Highlights where variations in meteorological factors or their interaction explain cotton yield variability in China. [ABSTRACT FROM AUTHOR]

Planting density management can regulate cotton (Gossypium hirsutum L.) biomass accumulation and seed cotton yield formation, which are associated with water consumption. However, it is unclear whether modifying the planting density affects the water use in different soil layers and thus regulates the plant growth and yield formation of cotton. In a two-year field experiment in 2020–2021, cotton was grown at various plant densities (1.5, 3.3, 5.1, 6.9, 8.7, and 10.5 plants m−2), and the spatial profile of water consumption, plant height, the leaf area index (LAI), biomass accumulation, and seed cotton yield were evaluated. The results showed that increase in planting density leads to more water consumption in the middle and lower soil layers (40–80 and 80–120 cm), and improved water use efficiency (WUE) in each soil layer (0–40, 40–80, 80–120 and 0–120 cm). The difference in plant height was attributed to cumulative total water consumption (0–120 cm), and the variation in LAI was due to planting density and cumulative total water consumption. More aboveground biomass at higher planting density was mainly attributed to more water consumption of the middle and lower soil layers (40–80 and 80–120 cm). Additionally, excessively high planting density may lead to the premature senescence of root systems, as the correlation between the water consumption at 40–100 cm and belowground biomass was weaker under high planting density. Moreover, the WUE at 0–40 cm was proportional to the boll distribution on the lower part (1st-6th fruiting branches) of the plant and boll number per unit area, was inversely proportional to boll weight and harvest index (HI), and had parabolic relationship with seed cotton yield (y = −426.83 +244.50–3.48x2). Taken together, our data focused on the effects of water use in various soil layers induced by planting density on cotton growth and yield formation; moreover, these findings fill knowledge gaps within cotton science and provide a feasible direction for determining reasonable water management practices on the North Plain China. • Monitoring soil moisture with high spatiotemporal resolution. • Increasing planting density is expected to promote the water utilization in deep soil layers. • It is more likely that the increase of water use efficiency (WUE) of the 0–40 cm soil layer is at the expense of yield. [ABSTRACT FROM AUTHOR]

Introducing cover crops in monocropping systems to improve soil health has been broadly adopted worldwide. However, the impacts of different cover cropping systems on soil emissions and related soil fractions and their regulatory mechanism remain elusive. In this study, four cropping systems, i.e., relay intercropping with Orychophragmus violaceus L./cotton (OvC), Vicia villosa Roth/cotton (VvC), a cover crop mixture (Ov and Vv)/cotton (MSC) and a fallow field–cotton (FFC) system, were combined with four N application rates in a two-rotation cycle (2019–2021) to evaluate the effects on soil greenhouse gases (GHGs) emission, ammonia (NH 3) volatilization, and labile carbon (C) and nitrogen (N) fractions and their relationships. Compared with the FFC system, the cumulative NH 3 volatilization and nitrous oxide (N 2 O) emissions of OvC are noticeably reduced 13% and 58%, respectively, and those of VvC are comparable, while those of MSC are markedly increased by 15% and 24%, respectively. N fertilization significantly affects soil NH 3 volatilization and N 2 O emissions, and a higher N rate results in more gaseous N emissions. In addition, NH 3 volatilization and N 2 O emission are positively correlated with the soil microbial biomass N (MBN), dissolved organic N (DON), NH 4 +-N and NO 3 --N but negatively correlated with microbial biomass C (MBC) and dissolved organic C (DOC). OvC system decreased gaseous N emission by high soil MBC/MBN ratio, Vv as cover crop indirectly promote soil N 2 O emission through increased soil MBN, DON and MBC content, while cover crop mixtures increase soil labile C and N fractions and enhance gaseous N emission ultimately. Overall, application of N fertilizer and cover crop mixture both promoted soil NH 3 and N 2 O emissions; the relay intercropping nonlegume cover crop Ov noticeably mitigates N 2 O and NH 3 emissions through an increase in the soil MBC and reduce in the labile N, while introduction of the legume cover crop Vv increases N 2 O emissions but reduces soil NH 3 volatilization due to a lower soil MBC/MBN ratio. • Soil NH 3 volatilization and N 2 O emission depend on different cover cropping system. • Soil labile C and N fraction increased due to relay intercropping cover crops. • Planting O. violaceus in winter fallow mitigated annual soil NH 3 and N 2 O emissions. • O. violaceus and V. villosa cover crop mixtures enhanced soil gaseous N emission. • Soil MBN, NH 4 +-N and NO 3 --N are key factors to promote soil gaseous N loss. [ABSTRACT FROM AUTHOR]

Approximately 70% of global cotton production is under the threat of drought. Changing cropping systems is an agronomic measure that potentially coordinates production and ecology. However, little evidence is available on the characteristics of changes in the soil moisture under different cropping systems and their relationships with cotton production. This study assessed the temporal and spatial variation in the soil moisture and analyzed the relationships between the soil water content (SWC) and the biomass, yield, and water use efficiency (WUE) of cotton (Gossypium hirsutum L.) in three cropping systems (monoculture cotton (MC), wheat (Triticum aestivum L.)/delayed intercropped cotton (WIC), and wheat/direct-seeded cotton (WDC)). The spatiotemporal heterogeneity and autocorrelation of the soil moisture were affected by cropping systems and whether the soil was dry or wet. Compared with the values in 2016 (moist), the spatiotemporal heterogeneity in the SWC variation at a 10–110 cm depth in the three planting systems increased, and the autocorrelation decreased in 2017 (drought). This phenomenon was more pronounced in WIC than in MC and WDC. Compared with MC, the double-cropping system increased the SWC between cotton rows. In the double-cropping system, the cotton yield of WIC was significantly higher than that of WDC. The order of WUE from high to low was WDC>MC>WIC in 2016 and MC>WIC>WDC in 2017, and no significant difference was observed between MC and WIC in both years. Yield limitation in the double-cropping system was due to weak water absorption of roots. The growth curves of cotton roots with increasing SWC in WIC were similar to those in MC, while WDC showed faster root growth but a smaller maximum value. The roots in WDC stopped growing when the water consumption reached 150 mm. WDC with a small root system was suitable for humid regions, while WIC with a strong root system should be promoted in both humid and arid regions. The methods and results can be used to obtain a deeper understanding of the effects of different planting systems on soil moisture and cotton production and to determine their interrelationship to guide dryland cotton production and precision agriculture. [Display omitted] ● Soil water monitoring in cotton fields with high spatial and temporal resolution. ● The wheat-cotton double cropping improves the soil water status in the field. ● The yield limit in double-cropped cotton is due to weak water use by smaller roots. ● The wheat/delayed intercropped cotton is better in terms of efficient water use. [ABSTRACT FROM AUTHOR]

• A new method for visualizing the spatiotemporal change in soil water consumption. • The complexity of crop responses to multiple environmental factors is highlighted. • The main factor driving cotton biomass formation is water consumption. • Cotton yield exhibits a significant positive correlation with PE GDD and PE soil. • MC and WIC had high cotton yield and accumulated temperature production efficiency. In the context of intensified climate change, approximately 70% of global cotton (Gossypium hirsutum L.) production is in arid or high temperature environments. Improving cultivation practices is an effective measure to promote the adaptation of cotton production to the climate. To comprehensively study the characteristics of the hydrothermal microclimate in cotton fields and their relationship with cotton biomass and yield formation, a grid sampling method based on sensors with high spatiotemporal resolution was used in this study to monitor the soil temperature and soil moisture under three cropping patterns (monoculture cotton (MC), wheat (Triticum aestivum L.)/delayed intercropped cotton (WIC), and wheat/direct-seeded cotton (WDC)). The cropping patterns substantially changed the cotton hydrothermal resource utilization. WDC was the pattern with low cotton yield and low hydrothermal resource use efficiency, while MC and WIC were the patterns with high cotton yield and high accumulated temperature production efficiency. Cotton yield exhibited a very significant positive correlation with the accumulated temperature production efficiency of air and soil, and these relationships were less affected by different planting patterns. The climate in 2016 was relatively humid, and the water consumption (WC) of MC was mainly concentrated within a soil depth of 70 cm, WIC was 50 cm, and WDC was 30 cm. The climate in 2017 was relatively dry, and the main soil depth ranges of WC in MC, WIC, and WDC were 50, 30, and 20 cm, respectively. WC was the most important factor affecting cotton biomass, especially reproductive organ biomass, followed by the effective accumulated air temperature. The WC of cotton was most affected by changes in soil moisture at a depth of 30 cm. This study strengthens the application of smart agricultural technology in sustainable cotton production and highlights the complexity of crop responses to cultivation practices and multiple environmental factors. [ABSTRACT FROM AUTHOR]

Volumetric soil water content (VSWC) monitoring is an important aspect of environmental monitoring of farmland. Accurate and real-time determination of the VSWC is important for crop drought stress diagnosis and smart irrigation. Image technology is commonly used in agricultural information technology. Based on image technology, we simulated the optimal frequency of the sensors to automatically collect VSWC data, thereby solving the problems of data redundancy and data analysis difficulties in real-time monitoring. In this study, a cotton field under mulched drip irrigation in 2018 was utilised as the research subject, 5TE sensors were arranged on the soil profile of the cotton field using the "grid method", and Voxler and Surfer software was used to model the VSWC data and draw contour maps. Image processing technology (image greyscale and image similarity comparison) was employed to determine the image algorithm suitable for contour map pre-processing and the best time period for VSWC monitoring. These results indicated that the contrast-limited adaptive histogram equalisation (CLAHE) greyscale algorithm is a suitable pre-processing algorithm for processing contour maps using image processing technology, and the best 5TE sensor data monitoring time period is every 10 h. This conclusion provides a theoretical reference for VSWC monitoring and water management in production. • Image technology can be used for VSWC data processing. • CLAHE is a suitable greyscale algorithm for VSWC contour maps. • The longest interval for acceptable VSWC data with 5TE was 10 h. [ABSTRACT FROM AUTHOR]

Winter cover crop cultivation during the fallow season has been strongly recommended in single crop cropping systems to improve soil quality, but its impact on the soil greenhouse gas (GHG) emissions of the soil has not been extensively studied. This study aimed to investigate the effects of replacing traditional winter fallow with a cover crop combined with a reduced amount of nitrogen (N) fertilizer on ammonia (NH 3) volatilization, GHG emissions, and cotton production yield. A field experiment was performed with two cropping systems (a single cotton system and February orchid (Orychophragmus violaceus L.) incorporated into a single cotton cropping system) and four N levels (0, 112.5, 168.75 and 225.0 kg N ha−1). The results showed that the incorporation of February orchid increased cotton yield, nitrous oxide (N 2 O) emission, NH 3 volatilization, global warming potential (GWP), and net ecosystem carbon budget (NECB) under the same N application rate. Moreover, the NH 3 , N 2 O, GWP, yield GWP, and NECB increased with an increasing N application rate. Furthermore, the correlation and redundancy analysis (RDA) results indicated that N 2 O emissions and NH 3 volatilization were positively affected by soil NO 3 - -N, total nitrogen (TN) and lint cotton yield. Overall, compared with the single cropping of cotton with conventional fertilization, the incorporation of February orchid with a 25% reduction in the N application rate decreased NH 3 volatilization by 1.05 kg NH 3 -N ha−1 and N 2 O losses by 0.34 kg N 2 O-N ha−1 and resulted in a favorable cotton yield. Our results demonstrate that replacing traditional winter fallow with a cover crop combined with a N fertilizer reduction may help to mitigate soil GHG emissions and NH 3 volatilization while ensuring yield in cotton production. In future studies, the evaluation of cropping system GHG emissions should be considered from a life-cycle perspective, and attention should be given to the legacy impacts of N. • Soil NH 3 volatilization and N 2 O emissions decreased with nitrogen fertilizer reduction. • The incorporation of February orchid increased soil N 2 O emission. • Effect of February orchid incorporation on soil NH 3 volatilization was not significant. • Cover crop combined with nitrogen reduction can ensure cotton production. [ABSTRACT FROM AUTHOR]

Appropriate use of cover crops and crop rotation in agriculture can contribute to food security and sustainable production. However, the impacts of Orychophragmus violaceus (O. violaceus) as rotation cover crop in maize on soil physicochemical properties and crop nutrient uptake have rarely been verified and quantified via field studies. With a conventional wheat (Triticum aestivum L.)-maize (Zea mays L.) rotation used as a control, a field experiment was conducted on the North China Plain in 2017–2018 and 2018–2019 to evaluate the dynamic variations in soil chemical properties and maize agronomic indexes and the impacts on maize nutrient uptake and yield under continuous maize and O. violaceus -maize rotation. We observed that rotation of O. violaceus with maize positively impacts soil chemical properties and subsequent maize productivity. Compared to those in the wheat-maize rotation, the mean contents of soil organic matter (SOM), soil alkali–hydrolyzable nitrogen (SAN), soil available phosphorus (SAP), and soil available potassium (SAK) in the O. violaceus -maize rotation increased by 8%, 11%, 13% and 18%, respectively, within the 0–60 cm soil layer, thereby increasing the maize N and P uptake and yield at maturity. According to correlation analysis and path model results, the most powerful direct factor affecting the maize yield was plant nutrient uptake rather than biomass accumulation. The O. violaceus -maize rotation was superior to the wheat-maize rotation and continuous maize in term of SOM, SAN, plant agronomic indexes, and maize nutrient uptake and yield. Overall, O. violaceus -maize is a reasonable rotation system for use on the North China Plain and provides new insight into the mechanisms and processes underlying crop yield and nutrient uptake. • O. violaceus -maize greatly increased soil organic matter and soil available nitrogen. • The maize nutrients uptake was increased at maturity in O. violaceus -maize system. • Replacing wheat or fallow field with O. violaceus increased maize yield by 8%−12%. • The relationship between soil chemical property and maize yield was quantified. [ABSTRACT FROM AUTHOR]

Introducing cover crops into crop rotation systems is widely practiced to enhance the sustainability of agricultural production, but comprehensive evaluations of farmlands in cover crop-maize rotations on the North China Plain (NCP) from environmental, economic and net ecosystem economic benefits (NEEB) perspectives have rarely been performed. Therefore, a field experiment was conducted to compare economic benefits (EB), greenhouse gas (GHG) emissions, reactive nitrogen (Nr) losses, soil nutrient cycling values (SNV) and NEEB in three farming systems. The farming systems included a conventional wheat-maize (WM) rotation system, a government-promoted monoculture maize (MM) system and an innovative Orychophragmus violaceus (O. violaceus)-maize (OvM) rotation system. The OvM rotation system achieved more EBs from the maize season but lower annual profits than the WM system, with 68.29% lower GHG emissions and 39.33% lower Nr losses. In addition, the highest SNV was achieved in the OvM rotation system, which was 700.18% and 116.97% higher than those in the WM and MM systems, respectively. Furthermore, the NEEB of the OvM rotation system was 61.92% and 29.31% higher than those of the WM and MM systems, respectively. In conclusion, the OvM rotation is recommended as a sustainable and cleaner maize production farming system for the NCP and other regions with similar ecological conditions because it led to lower annual GHG emissions and Nr losses, as well as higher SNV and NEEB than the other farming systems. [Display omitted] • Replacing wheat or fallow field with O. violaceus improved maize yield by 8%–12%. • GHG emission of O. violaceus -maize was lower by 68% than those in wheat-maize. • Nr loss was lower by 39% in O. violaceus -maize than those in wheat-maize. • NEEB was increased by 62% in O. violaceus -maize relative to wheat-maize. [ABSTRACT FROM AUTHOR]