Ecology and Environment Science
HU Xia, SONG Chuncao, ZHANG Xiting, ZHOU Mi, WANG Hanyu, PENG Yanjie, HUANG Jiao
Objective: To Explore the physiological responses of three moss plants to Cd stress and provide a useful reference for ecological restoration in Cd-contaminated areas. Methods: Thuidium cymbifolium, Dicranum nipponense and Racomitrium japonicum were used as materials in a laboratory Cd stress experiment. Through physiological and biochemical measurements, the response differences of chlorophyll mass fraction, osmoregulatory substances mass fraction, membrane damage degree, antioxidant enzyme activity, and enrichment characteristics of three moss plants to five different concentrations of Cd stress were compared to explore their sensitivity and tolerance to Cd stress. Results: Low mass concentration Cd stress(5 mg·L-1) activated the adaptive regulation of mosses, significantly enhancing the antioxidant enzyme(SOD, GPX) activity of Thuidium cymbifolium and Dicranum nipponense. The Chl mass fraction increased by 6.81% and 7.06% respectively compared to the control, and the SP mass fraction increased by 41.69% and 31.91%. High mass concentration of Cd stress(100 mg·L-1) resulted in a significant decrease in Chla, Chlb, and Chl mass fraction of three mosses(37.73%~44.55%, 28.50%~32.86%, 34.77%~40.74%, respectively), a significant increase in RC(34.73%~51.16%), a significant decrease in SP mass fraction(40.41%~66.67%), a significant decrease in GPX and SOD activities(10.66%~14.91%, 17.74%~25.00%, respectively). And the MDA mass fraction were 2.36, 2.79 and 3.77 times higher than the control, respectively. Interspecies comparisons revealed that Racomitrium japonicum was the most sensitive to Cd, showing a linear increase in Pro content with Cd concentration, the weakest antioxidant enzyme activity(GPX decreased by 14.9%), and the lowest tolerance indices(BCF=0.02, Ti=0.30) under high mass concentration Cd stress. In contrast, Thuidium cymbifolium exhibited the strongest tolerance, with the highest bioconcentration factor(BCF=0.03) and tolerance index(Ti=0.43), along with minimal declines in antioxidant enzyme activity. Conclusion: Thuidium cymbifolium is a potential candidate for ecological restoration in Cd-contaminated areas, while the low tolerance of Racomitrium japonicum could be used as a biomarker for monitoring early-stage Cd pollution.