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In saline and salinity-affected soils, the global productivity and sustainability of cotton are severely affected by soil salinity. High salt concentrations hinder plant growth and yield formation mainly through the occurrence of osmotic stress, specific ion toxicity, and nutritional imbalance in cotton. A number of agronomic practices have been identified as potential solutions to alleviate the adverse effects induced by salinity. While genetic breeding holds promise in enhancing the salinity tolerance of cotton, agronomic practices that improve the root zone environment, ameliorate soil conditions, and enhance salinity tolerance are currently considered to be more practical. This compressive review highlights the effectiveness of agronomic practices, such as furrow seeding, plastic mulching, their combination, densely planting, and the appropriate application of fertilizer and plant growth regulators, in mitigating the negative impact of salinity on cotton. By implementing these agronomic practices, cotton growers can improve the overall performance and resilience of cotton crops in saline and salinity-affected soils. This review provides valuable insights into practical agronomic measures that can be adopted to counteract the adverse consequences of soil salinity on cotton cultivation. [ABSTRACT FROM AUTHOR]

Since the beginning of the 21 st century, the rapid economic development and accelerated urbanization of China have caused major changes to the country's cotton cultivation technology. China has not replicated the completely mechanized approach used in developed countries. Rather, taking into account the underdeveloped economy and family-scale based cotton growing, China has established and implemented a light and simplified system of sustainable cotton production. Light and simplified cultivation (LSC) involves using modern agricultural equipment and technology adapted to the local economic level and mode of management of cotton production instead of manual operations. This method reduces labor intensity, simplifies cultivation management, reduces the frequency of field operations, integrates agricultural machinery and agronomic technology, and uses high-quality seeds and improved techniques to achieve light, simplified, and cost-effective cotton production. Cotton LSC includes the following key technologies: Single-seed precision sowing, simplified plant pruning, light and simplified fertilization, water and fertilization integration technology, and plant population structure control. Single seed precision sowing technology ensures robust seedling growth via differential expression of the key genes controlling hook formation and hypocotyl elongation at seed germination. Cotton planting at a relatively high plant density inhibits the growth of vegetative branches via differential expression of genes for hormone metabolism and compartmentation of hormones within a cotton plant. The high and stable yield of LSC lies in the adaptive coordination between the cotton yield components and between the biomass and the harvest index. According to the appropriate leaf area index and its dynamics, quantitative indicators such as suitable plant height, the ratio of fruiting nodes to branches in number, and the ratio of seed cotton to stalks in weight can produce plant populations with high solar efficiency. The basis of light and simplified fertilization is that the absorption of fertilizer N by cotton is concentrated within 20 days after flowering, and the fertilizer applied at early flowering was mainly distributed to reproductive organs and had higher N use efficiency than that applied at other stages. The water saving mechanism of partial root-zone irrigation is that methyl jasmonate serves as a signal substance to enhance the water absorption from the hydrated root side. Future development of cotton cultivation must include an in-depth investigation of the ecophysiology of LSC to further reform and optimize the planting systems and patterns. Innovation in cultivation technologies, development of new materials and equipment, and integration of agronomic technology and materials may provide solid theoretical and technical support for LSC and promote the sustainable cotton production in China. [ABSTRACT FROM AUTHOR]

Plant density, nitrogen (N) fertilization rate and plant pruning are important measures used globally to cultivate cotton. A typical combination of 52,500 plants ha −1 , intensive pruning and 255 kg N ha −1 has been widely applied in the Yellow River Valley of China. The main objective of this study is to determine whether more beneficial combinations exist than the typical one for profitable cotton production in this region. Using a split–split plot design with four replications, we conducted a three-year field experiment to study the individual and interaction effects of plant density (52,500 and 82,500 plants ha −1 ), plant pruning (intensive and extensive) and N fertilizer rate (195 and 255 kg N ha −1 ) on yield, plant biomass and partitioning, N uptake and use efficiency, as well as input and output values. The results showed that cotton yield was affected by individual and interaction effects of the three agronomic factors. When planted at a moderate density (52,500 plants ha −1 ), the seedcotton yield of intensively pruned cotton under a low N rate (195 kg N ha −1 ) and of extensively pruned cotton under low and high (255 kg N ha −1 ) N rates was reduced by 6.9, 6.7 and 5.4%, respectively, whereas the four combinations with high plant density (82,500 plants ha −1 ) produced a yield value that was comparable to that of the typical combination, indicating a relatively stable yield at high plant density irrespective of pruning mode and N rate. Vegetative branches of the extensively pruned cotton accounted for 18.7–23.6% of the total biomass at moderate plant density compared with only 2.8–2.9% of the total biomass at high plant density. At moderate plant density, intensively pruned cotton exhibited a higher harvest index than the extensively pruned plants. By contrast, the harvest index for the four combinations with high plant density did not differ, suggesting a relatively stable harvest index among these combinations. There was no difference in the N biomass utility index (NBI) among all combinations. The combination of high plant density, extensive pruning and reduced N rate had a 6.7% lower nitrogen yield utility index (NYI) than the typical combination but a 5.4% higher NYI than the combination of high plant density, extensive pruning and high N rate. More importantly, the combination of high plant density, extensive pruning and reduced N rate produced comparable yield with less input, leading to 21.7% more net revenue than the typical combination. Our results support the use of high plant density, reduced N rate and extensive pruning to ensure profitable cotton production in the Yellow River Valley and other cotton-growing areas with similar ecologies. [ABSTRACT FROM AUTHOR]

Background: Cotton has tremendous economic value worldwide; however, its allopolyploid nature and time-consuming transformation methods have hampered the development of cotton functional genomics. The protoplast system has proven to be an important and versatile tool for functional genomics, tissue-specific marker gene identification, tracking developmental trajectories, and genome editing in plants. Nevertheless, the isolation of abundant viable protoplasts suitable for single-cell RNA sequencing (scRNA-seq) and genome editing remains a challenge in cotton. Results: We established an efficient transient gene expression system using protoplasts isolated from cotton taproots. The system enables the isolation of large numbers of viable protoplasts and uses an optimized PEG-mediated transfection protocol. The highest yield (3.55 × 105/g) and viability (93.3%) of protoplasts were obtained from cotton roots grown in hydroponics for 72 h. The protoplasts isolated were suitable for scRNA-seq. The highest transfection efficiency (80%) was achieved when protoplasts were isolated as described above and transfected with 20 μg of plasmid for 20 min in a solution containing 200 mM Ca2+. Our protoplast-based transient expression system is suitable for various applications, including validation the efficiency of CRISPR vectors, protein subcellular localization analysis, and protein–protein interaction studies. Conclusions: The protoplast isolation and transfection protocol developed in this study is stable, versatile, and time-saving. It will accelerate functional genomics and molecular breeding in cotton. [ABSTRACT FROM AUTHOR]

Cotton has a complex branching pattern including sympodial and vegetative branching. Traditionally managed cotton mainly depends on sympodial branching for formation of yield-contributing fruit. Whether seedcotton yield based solely on vegetative branching is comparable with that based solely on sympodial or both types of branching is unclear. The study determined how terminal removal at first square to avoid formation of sympodial branches (SBs) regulated vegetative branching and yield under different plant densities. A two-year split-plot design field experiment had main plots with plant density (4.5 and 9.0 plants m−2) and subplots with plant pruning mode. Pruning modes were terminal removal at first square (TRS) to avoid formation of sympodial branches but retain only vegetative branches (VBs), removal of VBs (RVB) to retain only SBs, and no pruning (CK), with both branch types remaining intact. Canopy photosynthesis, dry matter accumulation and partitioning, and seedcotton yield and yield components were examined. At low plant density (4.5 plants m−2), compared with other pruning modes, TRS increased seedcotton yield and biological yield but did not affect harvest index. At high plant density (9.0 plants m−2), compared with other pruning modes, TRS decreased seedcotton yield and harvest index, although biological yield increased. The yield increase with TRS at low plant density was attributed to the increase in biological yield, which was due to significantly higher canopy photosynthesis with TRS than with other pruning modes. At high plant density, photosynthesis with TRS was higher than that with no pruning at peak boll-setting and boll-opening stages and higher than that with RVB from peak squaring to boll-opening. Compared with other pruning modes, TRS increased dry matter partitioning to vegetative organs but decreased partitioning to reproductive organs. Pearson correlation analysis revealed a significant positive correlation between canopy apparent photosynthesis and biological yield, biomass partitioning, and harvest index, irrespective of plant pruning and plant density. Plant pruning and plant density interacted to affect seedcotton yield. With TRS, cotton yield at low plant density was higher than that with other pruning modes, which was attributed to an increase in biological yield associated with an increase in canopy photosynthesis. At high plant density, the yield decrease with TRS was attributed to low harvest index associated with reduced reproductive partitioning. Cotton cultivation relying solely on vegetative branching can be an alternative to obtain moderate yields and economic benefits under conditions of low plant density. • Plant pruning and density affected cotton branching and yield formation. • Terminal removal at first square led to the highest seed cotton yield at low plant density. • Terminal removal at first square increased yield by promoting canopy photosynthesis. [ABSTRACT FROM AUTHOR]

Plastic film mulching has been widely applied to improve crop productivity of full-season cotton (Gossypium hirsutum L.). However, in a previous study, plastic mulching did not increase seed cotton yield of short-season cotton compared with non-mulching. The aim of this study was to determine why plastic mulching fails to increase seed cotton yield of short-season cotton. A short-season cultivar Lumian 532 was planted with or without plastic mulching at an experimental station in Linqing in the Yellow River valley of China in 2020 and 2021. Yield, yield components, leaf senescence, photoassimilate accumulation and partitioning, photohormone contents, expression of senescence-related genes, and root traits were examined each year. Seed cotton yield produced with plastic mulching was not significantly different from that produced with non-mulching in short-season cotton. Although number and size of early- and mid-season bolls were significantly greater with plastic mulching than with non-mulching, plastic mulching decreased number and size of late-season bolls by 34.0% and 8.8%, respectively. At the initial boll opening stage, photosynthetic rate and chlorophyll content in main-stem functional leaves were 36.2% and 24.1% lower, respectively, with plastic mulching than with non-mulching, but malondialdehyde content was 34.2% higher, suggesting that plastic mulching accelerated late-season leaf senescence. Canopy photosynthesis and photoassimilate partitioning to reproductive organs at the initial boll-opening stage were 68.1% and 9.4% lower, respectively, with plastic mulching than with non-mulching. Compared with non-mulching, plastic mulching increased abscisic acid and methyl jasmonate contents but decreased those of cytokinins content because of differential expression of hormone metabolism-related genes in late-season main-stem leaves. Plastic mulching also increased root distribution in the shallow soil layer and lowered root vigor in the late season, compared with non-mulching. Overall, plastic mulching negatively affected root distribution and function and altered expression of senescence-related genes and hormone metabolism-related genes to affect hormone balance, which led to accelerated late-season leaf senescence. Because of late-season leaf senescence, canopy photosynthesis and photoassimilate partitioning to cotton bolls were suppressed with plastic mulching, which led to fewer and smaller late-season bolls than those with non-mulching. Thus, plastic mulching failed to improve the seed cotton yield. This study provides a clear explanation of how plastic mulching causes late-season leaf senescence and further demonstrates that plastic film mulching is not required for planting short-season cotton in the Yellow River valley of China or in other cotton growing areas with similar ecology. • Plastic mulching did not increase yield compared with non-mulching because of fewer and smaller late-season bolls in short-season cotton. • Reduced number and size of late-season cotton bolls was attributed to accelerated late-season leaf senescence in short-season cotton. • Accelerated leaf senescence was due to shallow root distribution and weak root vigor, and differential expression of senescence-related genes. [ABSTRACT FROM AUTHOR]

Manual removal of the main-stem growth tip is traditionally used to break the apical dominance of cotton (Gossypium hirsutum L.). Chemical topping with plant growth regulators also effectively inhibits apical dominance. However, the effect of chemical topping on yield increases and whether plant density or ecological conditions affect its efficacy are unclear. Therefore, a three-year field experiment with a split-plot design was conducted to determine the effects of plant topping, plant density, and their interactions on cotton yield and related physiological and agronomical parameters at three sites with different ecological conditions in China. In each site, the main plots were assigned low, moderate, or high plant density and the subplots were assigned no topping, manual topping, or chemical topping. Growth, yield, yield components, earliness, and late-season leaf photosynthesis as well as labor and material inputs were examined each year. Compared with no topping, both chemical and manual topping greatly reduced plant height at all sites. Manual topping increased seed cotton yield and earliness in all tested plant densities and sites. However, plant density but not ecological condition greatly mediated the effect of chemical topping on yield. At low plant density, the yields with chemical topping were 4–6% lower than those with no topping and 5.5–10.8% lower than those with manual topping at the three sites. Although yields with chemical topping were comparable with those of manual topping at moderate and high plant densities, they were 8.6–12.8% higher at moderate density and 13.8–16.4% higher at high plant density than those with no topping across years and sites. Averaged across the sites, chemical topping reduced biological yield by 12.7% at low plant density. Although biological yield decreased slightly, chemical and manual topping increased the harvest index by 12.4% and 13.3% at moderate density and by 15.6% and 17.4% at high density, respectively. In comparison with no topping, the reduction in seed cotton yield with chemical topping at low plant density was attributed to insufficient biological yield, whereas the increase in yield at moderate and high plant densities was mainly due to greater partitioning of assimilates to reproductive tissues. Compared with manual topping, chemical topping produced 23.2% lower net returns as a result of lower seed cotton yield at low plant density but produced 8.1% and 20.9% higher net returns at moderate and high plant densities, respectively, because of savings in labor inputs and comparable seed cotton yields. In addition, chemical topping increased the earliness percentage compared with that of no topping. Overall, this study demonstrates that chemical topping is a promising alternative to traditional manual topping under moderate or high cotton plant density. • Manual topping increased cotton yield regardless of plant densities and ecological conditions relative to non-topping. • Chemical topping decreased yield at low plant density relative to non-topping because of greater biomass reduction. • Chemical topping increased cotton yield at moderate and high plant densities via greater assimilates partitioning to fruits. • Chemical topping could replace manual topping at moderate and high plant densities without ecological dependence. [ABSTRACT FROM AUTHOR]

• Non-mulched short-season cotton produced less fiber but greater returns than mulched full-season cotton as it consumed less inputs. • Non-mulched short-season cotton delayed leaf senescence due to reduced boll load and produced comparable cotton yields to the mulched. • Non-mulched short-season cotton reduced the residual film pollution, thus offering an alternative to mulched full-season cotton. The early planting of full-season cotton (Gossypium hirsutum L.) at a moderate plant density under plastic mulching is a traditional means of growing cotton in the Yellow River valley of China. However, it is labor intensive, consumes a large amount of materials, and also results in residual plastic pollution in the soil. While our previous studies indicated that late planted short-season cotton under plastic mulching greatly reduces labor and material inputs and increases net revenue, the residual plastic pollution remains an issue. It is unclear if short-season cotton can be managed without yield loss in the absence of plastic mulching. A field experiment was therefore conducted using a random complete block design with four treatments, including the early planting of full-season cotton with (FCM) and without plastic mulching (FC), and the late planting of short-season cotton with (SCM) and without plastic mulching (SC), in the Yellow River valley from 2017 to 2019. The yield, yield components, input and output values, earliness, dynamics of flowering and boll setting, and late-season leaf senescence in cotton were examined. The results showed that early planted full-season cotton under mulching (FCM) produced a 21.1 and 20.4 % higher seedcotton yield and boll density, respectively, and improved earliness over the non-mulched treatment, while the boll weight did not differ significantly. Short-season cotton without plastic mulching produced comparable seedcotton yields to that with mulching (SCM), and there was no significant difference in average boll weight, boll density, or earliness between the mulching and non-mulching treatments. However, SC had a 7.0 and 12.1 % smaller boll density and boll weight, respectively, than FCM and thus produced a 17.9 % lower seedcotton yield. Therefore, SC produced 14.9 and 14.4 % greater net returns than SCM and FCM, respectively, because it consumed less labor and material inputs. Short-season cotton without plastic mulching delayed leaf senescence due to reduced boll load and thus increased boll weight in the late season compared with SCM. In addition, SC exhibited improved earliness as a result of a higher flowering rate, faster fruiting, and more concentrated boll opening than FCM. Short-season cotton without plastic mulching also avoided the residual film pollution in the soil. The overall results demonstrated that the late planting of short-season cotton without mulching is a promising alternative for sustainable cotton production in the Yellow River valley region of China as well as other cotton growing areas with similar ecology. [ABSTRACT FROM AUTHOR]