Enhancing chrysanthemum rooting: The role of Stenotrophomonas pavanii KC 98 in physiological and microbial dynamics

• Stenotrophomonas pavanii KC 98 significantly promoted the rooting of chrysanthemum cuttings. • KC 98 significantly increased the contents of physiological indicators such as chlorophyll and nutrients. • Inoculating with KC 98 increased the beneficial bacteria and decreased the pathogenic bacteria. The continuous cultivation of chrysanthemums has decreased rooting success in cuttings, adversely affecting plant performance and reproductive efficiency. However, treatment with Stenotrophomonas pavanii KC 98 significantly improved rooting outcomes, resulting in increases of 28.89 % in rooting rate, 26.85 % in the number of roots, 18.65 % in root length, and 35.77 % in dry root weight. Additionally, soluble sugars, hormones like indole-3-acetic acid (IAA), peroxidase (POD) activity, and chlorophyll content significantly improved by KC 98, and POD activity increased significantly by 53.51 %. The relative abundance of Ochrobactrum and unclassified Rhizobiaceae were significantly increased by KC 98, while the diversity of endophytes and rhizosphere microorganisms in chrysanthemum cuttings was significantly reduced. The abundance of Ochrobactrum with IAA and 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase production capacity in the endophytic and rhizosphere of chrysanthemum cuttings was increased by 74.62 % and 27.41 %, respectively. The redundancy analysis (RDA) indicated that beneficial bacteria Ochrobactrum and unclassified Rhizobiaceae exhibited positive correlations with physiological indicators such as chlorophyll and nutrients. Furthermore, KC 98 significantly decreased the relative abundance of plant pathogens such as Alternaria and Botrytis , indicating that KC 98 can potentially lower disease incidence. According to functional predictions, the abundance of the porphyrin and chlorophyll metabolism pathway increased by 41.36 % after KC 98 treatment. This result aligns with the phenotypic indicator's significant 23.76 % rise in chlorophyll content. In summary, KC 98 promoted the growth of various indicators related to rooting. It altered the community composition and potential functions of the endophytic and rhizosphere microorganisms, thereby facilitating the rooting of chrysanthemum cuttings.