Physiological Responses of Anoectochilus roxburghii to Salt Stress

Salt stress is a significant environmental factor influencing plant growth and development. Anoectochilus roxburghii is a valuable medicinal plant, but it is still unclear how it responds to salinity. In this study, A. roxburghii was used as experimental material to investigate its physiological mechanisms underlying salt stress resistance. Seedlings were subjected to various NaCl concentrations (0, 50, 100, 150, and 200 mmol/L), and changes in key physiological parameters were subsequently analyzed. The results indicated that under NaCl-induced salt stress, the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX), as well as soluble protein content, initially increased and then decreased, with peak levels observed between 100 and 150 mmol/L. Malondialdehyde (MDA) content exhibited a steady increase with rising salt concentration. Total chlorophyll content declined progressively, while anthocyanin content increased initially but decreased significantly when NaCl concentration exceeded 100 mmol/L. Additionally, the contents of total flavonoids and total phenolics decreased markedly at salt concentrations above 100 mmol/L. These findings suggest that A. roxburghii can tolerate salt stress up to 100 mmol/L for 24 h without exhibiting substantial physiological or morphological damage. This study provides a theoretical basis for analyzing the salt tolerance mechanism of A. roxburghii.