| 摘要 |
［Objectives］ To investigate the effects of single and combined stress of As5+ and Cd2+ on the quality and safety of using forage mulberry leaves. ［Methods］ Using the mulberry cultivar ‘Yuesang 51’ as the experimental material, a hydroponic experiment was conducted with single and combined As5+ and Cd2+ stress at concentration gradients ranging from 0 to 100 mg/L. The contents of total chlorophyll, soluble sugar, soluble protein, and malondialdehyde (MDA) in the leaves of mulberry seedlings were measured. Arsenic contents and cadmium contents in the roots, stems, leaves, and branches of the seedlings were determined by atomic fluorescence spectrometry (AFS) and atomic absorption spectrometry (AAS), respectively. ［Results］ The severity of effects on mulberry seedlings under different heavy metal stress treatments followed the order: combined As5+ and Cd2+ stress >single Cd2+ stress >single As5+ stress. Single stress of low-concentration As5+ or Cd2+ promoted physiological metabolism in mulberry leaves and increased the contents of soluble sugar and soluble protein. In contrast, combined As5+ and Cd2+ stress inhibited physiological metabolism in mulberry leaves and markedly decreased the soluble protein content. Mulberry seedlings showed a relatively strong capacity for Cd2+ uptake. For both As and Cd, the contents in different plant parts were consistently ranked as root >stem >leaf >branch. Under combined stress, Cd content decreased while As content increased. The arsenic content in mulberry leaves was relatively low, but the cadmium content exceeded the national limit for plant-derived feed ingredients. ［Conclusions］ As5+ and Cd2+ stress exerts a considerable effect on the quality of forage mulberry leaves. Under both single and combined stress, when the concentrations of As5+ and Cd2+ in the solution exceed a certain range, the cadmium content in the leaves significantly exceeds the national limit, potentially posing a safety risk for their use as feed. |
