Physiological response and shade tolerance of three Ranunculaceae ground cover plants under different shading treatments

This study investigated the shade tolerance of three wild ground cover plants in the family Ranunculaceae under different shade conditions. Ranunculus japonicus, Thalictrum fortunei, and Delphinium anthriscifolium var. savatieri were used as test materials. The plants were grown in an artificial shed and subjected to four shading treatments: 30%, 50%, 70%, and 90% shade, with full light as the control. The morphological and physiological indexes of the test materials were determined, and their shade tolerance was analyzed comprehensively. As the shading rate increased, several effects were observed. For all three species tested, the leaf area, leaf length, leaf width, plant height, plant width, and stem diameter first increased then decreased; peroxidase activity and malondialdehyde content first decreased then increased; and the specific leaf weight decreased. The superoxide dismutase activity of R. japonicus and D. anthriscifolium var. savatieri decreased gradually, while that of T. fortunei first decreased then increased. The catalase activity of R. japonicus decreased, while those of T. fortunei and D. anthriscifolium var. savatieri first decreased then increased. The proline content of R. japonicus and T. fortunei first decreased then increased, while that of D. anthriscifolium var. savatieri decreased gradually. Changes in the morphological and physiological indexes varied between the three plant species. A comprehensive evaluation of shade tolerance using the membership function method showed that shade tolerance followed the order T. fortunei > D. anthriscifolium var. savatieri > R. japonicus. The different degrees of negative tolerance shown by the three plant species can provide a theoretical reference for cultivating them under different shade conditions.