Challenges significantly hinder the sustainable cultivation of tea chrysanthemum, leading to imbalances in soil nutrients, the accumulation of allelopathic phenolic acids, reduced enzymatic activity, and disruptions in rhizosphere microbial communities. To explore potential mitigation strategies, this study systematically evaluated the integrative effects of exogenous methyl jasmonate (MeJA, 0–400 (μmol L⁻¹)) on both soil environmental parameters and plant growth performance under continuous cropping conditions. The results revealed that treatment with 100 (μmol L⁻¹) MeJA significantly enhanced plant height, canopy width, flower number, and fresh flower weight. Concurrently, it improved soil organic matter content, the available nitrogen levels, and redox stability while increasing the activity of key enzymes, including polyphenol oxidase, urease, and catalase. Notably, this treatment markedly reduced the accumulation of allelopathic phenolic acids, such as p-hydroxybenzoic acid and vanillic acid. High-throughput sequencing further demonstrated that 100 (μmol L⁻¹) MeJA optimized the composition of soil microbial communities, increasing the abundance of beneficial taxa, such as nitrogen-fixing and phosphate-solubilizing bacteria, while suppressing pathogenic fungi. Metabolomic analysis showed that this concentration of MeJA activated stress-resistance metabolic pathways involving flavonoids and terpenoids while downregulating degradation-related processes, thereby supporting enhanced plant resilience at the metabolic level. Collectively, these findings demonstrate that an appropriate concentration of exogenous MeJA can effectively alleviate continuous cropping obstacles in Chrysanthemum morifolium, providing both theoretical insights and practical guidance for its eco-friendly and efficient cultivation.

Wild orchid populations are declining with intensified habitat fragmentation posing severe challenges to germplasm conservation. As an important ornamental Orchidaceae species, Cymbidium ensifolium has abundant germplasm resources and frequent natural and artificial hybridization. Long-term natural evolution and anthropogenic disturbance have led to complex genetic backgrounds and ambiguous phylogenetic relationships hindering accurate germplasm identification, elite resource excavation, and selective breeding. As a distinctive variety, Cymbidium ensifolium var. susin has great breeding potential. Clarifying its phenotypic and genetic characteristics is crucial for accelerating breeding progress. In this study, phenotypic determination, Hyper-seq reduced-representation genome sequencing, SNP/InDel genotyping, genetic diversity analysis, and core collection construction were used to evaluate the genetic diversity, population differentiation, and core germplasm screening of 13 Cymbidium ensifolium var. susin accessions. The results showed significant phenotypic differences and rich genetic variation among tested materials. Based on highly weighted floral traits, accessions were divided into three major phenotypic groups. At the molecular level, 963,239 SNP and 182,399 InDel loci were identified and mainly distributed in intergenic regions, followed by introns and exons. A phylogenetic tree was constructed from SNP loci combined with principal component and phenotypic clustering analyses. This study preliminarily clarified the genetic structure of pure-heart Cymbidium ensifolium var. susin, showing a distinct geographical pattern: “high consistency in Fujian and Guangdong; strong differentiation in Southwest China; and a transitional gradient in Central China”. Meanwhile, six core germplasm accessions were screened in this study, which provides a solid theoretical basis and material support for the conservation of pure-heart Cymbidium ensifolium var. susin accessions, variety improvement, hybrid parent selection, and molecular marker-assisted breeding. This is of great significance for promoting the innovation of Chinese orchid germplasm resources and the high-quality development of the industry.

Wild orchid populations are declining with intensified habitat fragmentation, posing severe challenges to germplasm conservation. As an important ornamental Orchidaceae species, Cymbidium ensifolium has abundant germplasm resources and frequent natural and artificial hybridization. Long-term natural evolution and anthropogenic disturbance have led to complex genetic backgrounds and ambiguous phylogenetic relationships, hindering accurate germplasm identification, elite resource excavation, and selective breeding. As a distinctive variety, Cymbidium ensifolium var. susin has great breeding potential.Clarifying its phenotypic and genetic characteristics is crucial for accelerating breeding progress. In this study, phenotypic determination, Hyper-seq reduced-representation genome sequencing, SNP/InDel genotyping, genetic diversity analysis, and core collection construction were used to evaluate the genetic diversity, population differentiation, and core germplasm screening of 13 Cymbidium ensifolium var. susin accessions.The results showed significant phenotypic differences and rich genetic variation among tested materials. Based on highly weighted floral traits, accessions were divided into three major phenotypic groups. At the molecular level, 963,239 SNP and 182,399 InDel loci were identified, mainly distributed in intergenic regions, followed by introns and exons. A phylogenetic tree constructed from SNP loci, combined with principal component and phenotypic clustering analyses, clarified the genetic structure of pure-heart Cymbidium ensifolium var. Susin , showing a distinct geographical pattern: "high consistency in Fujian and Guangdong, strong differentiation in Southwest China, and a transitional gradient in central China".Meanwhile, six core germplasm accessions were screened in this study, which provides a solid theoretical basis and material support for the conservation of pure-heart Cymbidium ensifolium var. Susin accessions, variety improvement, hybrid parent selection, and molecular marker-assisted breeding. This is of great significance for promoting the innovation of chinese orchid germplasm resources and the high-quality development of the industry.