The problem of soil salinization has seriously hindered agricultural development. Cotton is a pioneering salinity-tolerant crop, so harvesting its key salinity-tolerant genes is important for improving crop salt tolerance. In this study, we analyzed changes in the transcriptome expression profiles of the salt-tolerant cultivar Lu Mian 28 (LM) and the salt-sensitive cultivar Zhong Mian Suo 12 (ZMS) after applying salt stress, and we constructed weighted gene co-expression networks (WGCNA). The results indicated that photosynthesis, amino acid biosynthesis, membrane lipid remodeling, autophagy, and ROS scavenging are key pathways in the salt stress response. Plant–pathogen interactions, plant hormone signal transduction, the mitogen-activated protein kinase (MAPK) signaling pathway, and carotenoid biosynthesis are the regulatory networks associated with these metabolic pathways that confer cotton salt tolerance. The gene-weighted co-expression network was used to screen four modules closely related to traits, identifying 114 transcription factors, including WRKYs, ERFs, NACs, bHLHs, bZIPs, and MYBs, and 11 hub genes. This study provides a reference for acquiring salt-tolerant cotton and abundant genetic resources for molecular breeding.

Fiber length is an important indicator of cotton fiber quality, and the time and rate of cotton fiber cell elongation are key factors in determining the fiber length of mature cotton. To gain insight into the differences in fiber elongation mechanisms in the offspring of backcross populations of Sea Island cotton Xinhai 16 and land cotton Line 9, we selected two groups with significant differences in fiber length (long-fiber group L and short-fiber group S) at different fiber development stages 0, 5, 10 and 15 days post-anthesis (DPA) for transcriptome comparison. A total of 171.74 Gb of clean data was obtained by RNA-seq, and eight genes were randomly selected for qPCR validation. Data analysis identified 6055 differentially expressed genes (DEGs) between two groups of fibers, L and S, in four developmental periods, and gene ontology (GO) term analysis revealed that these DEGs were associated mainly with microtubule driving, reactive oxygen species, plant cell wall biosynthesis, and glycosyl compound hydrolase activity. Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis indicated that plant hormone signaling, mitogen-activated protein kinase (MAPK) signaling, and starch and sucrose metabolism pathways were associated with fiber elongation. Subsequently, a sustained upregulation expression pattern, profile 19, was identified and analyzed using short time-series expression miner (STEM). An analysis of the weighted gene coexpression network module uncovered 21 genes closely related to fiber development, mainly involved in functions such as cell wall relaxation, microtubule formation, and cytoskeletal structure of the cell wall. This study helps to enhance the understanding of the Sea Island–Upland backcross population and identifies key genes for cotton fiber development, and these findings will provide a basis for future research on the molecular mechanisms of fiber length formation in cotton populations.

To elucidate the synergistic effects of nitrogen application rate and fertilization method on the yield and quality of high-quality japonica rice, a two-year field experiment (2024 and 2025) was conducted using Koshihikari with three fertilization methods—farmers’ practice (FP), light and simplified fertilization (LSF), and precise quantitative side-deep fertilization (PQSF)—and five nitrogen rates (0, 45, 90, 135, and 180 kg ha⁻¹). In 2024, comprehensive traits were evaluated, including grain-filling dynamics, protein fractions, panicle traits, milling quality, multidimensional quality, and yield. In 2025, only core yield and quality traits were measured for validation. Superior grains had higher filling rates and earlier initiation, whereas inferior grains showed delayed initiation and later peak timing; however, high nitrogen shortened effective filling duration and exacerbated delayed filling in inferior grains. Protein accumulation was closely associated with grain-filling parameters, with glutelin and prolamin showing more persistent associations than albumin and globulin. Milling quality was optimal at 90 kg ha⁻¹ (N90), whereas appearance and eating quality deteriorated with increasing nitrogen; springiness and adhesion force peaked at N45. Under high nitrogen, PQSF sustained inferior grain filling and mitigated the negative effects of excessive storage protein accumulation on eating quality. LSF achieved the highest yield (approximately 8900 kg ha⁻¹) within 135–153 kg ha⁻¹, whereas PQSF combined with 135 kg ha⁻¹ provided a quality-oriented strategy, increasing taste value by 3.00 and 2.33 points and reducing chalkiness percentage by 1.70 and 0.25 percentage points relative to FP and LSF, respectively, while maintaining lower hardness. PCA and hierarchical clustering analyses revealed that nitrogen rate established the fundamental framework for yield and quality, while fertilization method provided secondary regulation. The core yield and quality findings were consistent across both years, confirming the robustness of the conclusions and providing a basis for precise nitrogen management of high-quality japonica rice in the Liaodong coastal rice region; however, the mechanistic insights were mainly derived from 2024 and require further multi-year validation.