Study on physiological responses and Cs enrichment capacity of Moso bamboo in Cs-contaminated soil

Soil contamination by radioactive element cesium (Cs) is a growing environmental concern. Phytoremediation, employing cost-effective and environmentally sustainable plants, constitutes a promising strategy for mitigation. Moso bamboo (Phyllostachys pubescens), a species with high tolerance, economic value, and phytoremediation potential, is studied in this work. This study investigated the impacts of varying soil cesium concentrations (0, 5, 25, 50, 100, 150, 200 mg kg^-1 soil) on the growth, physiological and biochemical responses, as well as the accumulation and translocation of Cs in potted Moso bamboo seedlings. Moso bamboo seedlings demonstrated optimal performance at 50 mg kg^-1, achieving maximum values in growth attributes (dry weight, plant height, and stem thickness), net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO₂ concentration (Ci). This suggests a stimulatory effect of low Cs levels on plant vigor. Results indicate that SOD, CAT, and APX reached peak levels at a concentration of 100 mg kg^-1 Cs. However, these positive indicators declined progressively with higher Cs concentrations. At the highest concentration of 200 mg kg^-1, notable decreases in chlorophyll a, chlorophyll b, and total chlorophyll levels were observed, concomitant with elevated malondialdehyde (MDA) levels, indicative of oxidative stress. Despite this stress, substantial Cs accumulation occurred, reaching 476.33 mg kg^-1 in roots, 183.48 mg kg^-1 in stems, 675.88 mg kg^-1 in leaves at 200 mg kg^-1 soil Cs. Crucially, both the bioconcentration factor (BCF > 1) and translocation factor (TF > 1) exceeded unity, demonstrating significant Cs tolerance coupled with considerable uptake and translocation capacity. These findings underscored the considerable potential of Moso bamboo for Cs phytoremediation, and provided a robust theoretical foundation and valuable insights for utilizing this species in the remediation of Cs-contaminated soils.