Seedling emergence is a major determinant of stand establishment and subsequent yield formation in cotton (Gossypium hirsutum L.), yet it is highly vulnerable to early-season low temperature and soil salinity. This review synthesizes morphological, physiological, genetic, and mechanobiological advances to propose that hypocotyl elongation and apical hook development operate as a coordinated “elongation–protection” unit during cotton emergence. Hypocotyl cell expansion and cell-wall loosening generate the driving force needed for soil penetration, whereas hook curvature, produced by differential growth, buffers mechanical stress and protects the shoot apical meristem. We show that emergence failure under low temperature and salinity often occurs after germination, at the soil-penetration stage, when reduced elongation capacity, unstable hook curvature, or premature hook opening disrupt this integrated unit. Low temperature and salinity constrain emergence through convergent, multi-level mechanisms, including perturbed membrane/redox homeostasis, impaired energy metabolism, reduced cell-wall plasticity, and extensive rewiring of hormone biosynthesis, transport, and signaling. Recent advances further indicate that cell-wall integrity sensing, pectin remodeling, and energy–redox coordination are integral to the regulation of elongation and hook maintenance under stress. We propose a mechanistic framework linking hormone homeostasis, cell-wall mechanics, and morphogenetic output, in which auxin–ethylene coordination directs differential growth and hook curvature, gibberellins and brassinosteroids support elongation competence, and abscisic acid prioritizes stress responses. Cotton-specific evidence, including GhHLS1, GhSAL1, GhBRX family genes, and recent transcriptomic/network analyses, suggest that conserved regulatory modules are retained but rewired within a polyploid-specific regulatory architecture. Finally, we advance a unifying mechano-physiological concept of “resistance–driving force matching” and outline research priorities in quantitative mechanobiology, cotton-specific genetic regulatory network dissection, genetic variation mining, and integration with agronomic management and field phenotyping to improve stress-resilient cotton emergence.

Global cotton production faces mounting pressure to reconcile rising fiber demand with urgent sustainability imperatives, including water scarcity mitigation, greenhouse gas reduction, and agrochemical pollution control. Traditional practices, constrained by fragmented objectives and inherent trade-offs among yield, fiber quality, labor efficiency, and ecological impact, struggle to address these systemic challenges. Building upon previous concept of collaborative cultivation, this review for the first time introduces and comprehensively elaborates multi-objective integrated cotton cultivation (MOICC) - also referred to as integrated cotton cultivation (ICC) - a transformative framework centered on three pillars: dynamic trade-off management (e.g., region-specific priority adjustment), systematic technology integration (precision seeding, dense planting, chemical regulation, water-nutrient synergy, and targeted defoliation), and resource circularity (spatiotemporal optimization and waste recycling). MOICC overcomes sustainability bottlenecks by leveraging key physiological mechanisms, including ethylene signaling to enhance stress-resilient seedling establishment, jasmonate-mediated pathways to improve water/nutrient efficiency, canopy light competition coupled with hormonal regulation to eliminate manual pruning, and growth regulators to concentrate boll maturation. Case studies from diverse Chinese agro-ecosystems (e.g., Xinjiang, Yangtze/Yellow River basins) and intercropping systems demonstrate significant synergies: increased yield (8–22%), improved resource efficiency (water use efficiency increased by ≥20%, and nitrogen productivity up to 35 kg kg^–1), and enhanced environmental performance (labor reduction of 30–40%, carbon footprint reduction of 24–37%, and agrochemical savings: nitrogen reduction of 15–20% and pesticides reduction of 25%). Crucially, MOICC resolves core conflicts through integrated optimization: yield vs. quality (via ≥70% inner-position bolls), labor-saving vs. eco-safety (precision defoliant timing), and productivity vs. emissions (root-zone nitrogen monitoring). Future research priorities include deciphering multi-scale stress adaptation, developing intelligent decision-support systems (e.g., AHP-NSGA-II integration), advancing carbon-neutral value chains, addressing socio-economic adoption barriers, and fostering policy synergy. Overall, MOICC establishes a conceptually globally scalable pathway toward high-yield, superior-quality, resource-efficient, and ecologically sustainable cotton production, with potential applicability to other major cropping systems.

With the advancement of agricultural supply-side structural reforms and the growing demand for high-quality, safe, and eco-friendly agricultural products in China, cotton production now faces the challenge of coordinating multiple objectives, including yield enhancement, quality optimization, simplified and efficient management, and environmental sustainability. To address these challenges, this paper proposes the novel concept of multi-objective collaborative cultivation (hereafter termed “collaborative cultivation”). We systematically elaborate on the theoretical foundations underpinning this approach, including mechanisms of precision sowing for robust seedling establishment, synergistic water-fertilizer management under partial root-zone irrigation, population regulation through high-density planting with chemical regulation and pruning-free canopy shaping, physiological mechanisms of defoliation-ripening for synchronized boll maturation, and compensatory growth strategies ensuring yield stability under abiotic stress. Building on these theorical bases and international research insights, we identify four core technologies of collaborative cultivation: (i) precision sowing coupled with stress-resilient seedling establishment under adversity, (ii) high-density planting with chemical regulation for canopy shaping, (iii) variable-rate drip irrigation with water-fertilizer synergy management, and (iv) synchronized maturation control technology. Empirical evaluations demonstrate that the integrated application of these technologies optimizes resource utilization, enhances productivity, and ensures fiber quality consistency, while reducing labor inputs and chemical usage. Case studies from major cotton-producing regions validate that collaborative cultivation achieves synergistic outcomes in productivity, sustainability, and economic viability, aligning with green agricultural development goals. Future research priorities include optimizing multi-objective trade-offs, deciphering genotype-environment-management interactions, enhancing stress compensation mechanisms, and extending collaborative principles to multi-cropping systems. Through interdisciplinary innovation and technology integration, this framework offers a systemic solution for high-quality cotton industry development, demonstrating significant potential to drive the sector's green transformation and sustainable advancement.

Nitrogen (N) serves as an essential nutrient for yield formation across diverse crop types. However, agricultural production encounters numerous challenges, notably high N fertilizer rates coupled with low N use efficiency and serious environmental pollution. Deep placement of nitrogen fertilizer (DPNF) is an agronomic measure that shows promise in addressing these issues. This review aims to offer a comprehensive understanding of DPNF, beginning with a succinct overview of its development and methodologies for implementation. Subsequently, the optimal fertilization depth and influencing factors for different crops are analyzed and discussed. Additionally, it investigates the regulation and mechanism underlying the DPNF on crop development, yield, N use efficiency and greenhouse gas emissions. Finally, the review delineates the limitations and challenges of this technology and provides suggestions for its improvement and application. This review provides valuable insight and reference for the promotion and adoption of DPNF in agricultural practice.

Over the last few decades, waterlogging stress has increasingly threatened global cotton production. Waterlogging results in reduced soil oxygen, impairing the growth and development of this valuable crop and often resulting in severe yield loss or crop failure. However, as cotton has an indeterminate growth habit, it is able to adapt to waterlogging stress by activating three mechanisms: the escape, quiescence, and self-regulating compensation mechanisms. The escape mechanism includes accelerated growth, formation of adventitious roots, and production of aerenchyma. The quiescence mechanism involves reduced biomass accumulation and energy dissipation via physiological, biochemical, and molecular events. The self-regulation compensation mechanism allows plants to exploit their indeterminate growth habit and compensatory growth ability by accelerating growth and development following relief from waterlogging stress. We review how the growth and development of cotton is impaired by waterlogging, focusing on the three strategies associated with tolerance and adaptation to the stress. We discuss agronomic measures and prospects for mitigating the adverse effects of waterlogging stress.