Physiological and Biochemical Responses of Chrysanthemum × morifolium to Salinity Stress under In-vitro and in vivo Conditions

Salinity is a critical abiotic stress that significantly limits plant growth and productivity by disrupting physiological and biochemical processes. This study investigated the effects of NaCl-induced salinity on the in vitro culture of Chrysanthemum × morifolium Ramat. The present study investigated the induction, multiplication, rooting, and salinity tolerance of Chrysanthemum morifolium under both in-vitro and in-vivo conditions. Maximum shoot induction (89.66%) and proliferation (13.03 shoots per explant) were obtained on half-strength MS media supplemented with 2.0 mg/L BAP. To evaluate salinity tolerance, eight NaCl concentrations (0–300 mM) were tested in-vitro, showing highest regeneration at 25 mM and survival up to 30 days at 100 mM, indicating moderate tolerance. Salt primed microshoots were rooted efficiently (90.40%) on half-strength MS media containing 0.2 mg/L IBA, with the longest roots (12.30 cm) at 0.4 mg/L IBA. During the hardening phase, the highest survival rate was obtained using a potting mixture of coco peat, sand, vermicompost, and garden soil in a 2:1:1:1 ratio. In-vivo pot culture studies revealed that exposure to 100 mM NaCl resulted in moderate stress symptoms, whereas 200 mM NaCl caused pronounced growth inhibition, significant biomass reduction, leaf scorching, and necrosis. Physiological and biochemical analyses revealed that moderate salinity (25–100 mM) enhanced chlorophyll, carotenoids, and prolin, whereas severe salinity (≥ 200 mM) led to a sharp decline in pigments, elevated proline accumulation, and activation of antioxidant enzymes (SOD, CAT) to mitigate oxidative stress. This integrated in-vitro and in-vivo approach provides a robust platform for screening and developing salt-tolerant C. morifolium genotypes suitable for cultivation under saline conditions.