Effects of light intensities on morphological and physiological indexes of three ornamental cultivars of Saxifraga stolonifera

As a shade plant with high ornamental value, Saxifraga stolonifera is often used in landscape of courtyards and gardens. The light intensity may have an important infuence on its growth performance, especially on leaf color, formation and coloration of leaf variegation, which subsequently affects its ornamental value. However, the related study has not been reported before. In order to explore the adaptability of different cultivars of S. stolonifera to light intensity and understand their light or shade tolerance, three internationally-registered cultivars raised in China were used as the experimental materials, the effects of five light intensity treatments (100%, 85%, 60%, 40% and 15%) on plant growth and development and photosynthetic physiological indexes were investigated. The suitable indexes of light intensity for S. stolonifera were screened by the principal component analysis, and the light tolerance of the cultivars was evaluated by membership function analysis. The results were as follows: (1) The number of blades, leaf length, leaf width, leaf area, specific leaf area, chlorophyll a, chlorophyll b and total chlorophyll contents increased with shading. (2) The number of stolons, fresh weight above ground, dry weight above ground, stolon diameter, and the contents of carotenoid and flavonoids increased first and then decreased. (3) The maximum fluorescence value and the contents of soluble sugar, soluble protein and malondialdehyde of the leaves decreased with shading. (4) By analysis of principal component and membership function, the significant differences were found in the adaptability of the three cultivars to light intensity, ‘Xue Wen’ > ‘Tianmu Enci’ > ‘Hei Kui’. In which, 40% light intensity was optimal for ‘Xue Wen’, and 15%-40% light intensities were optimal for ‘Tianmu Enci’ and ‘Hei Kui’. Therefore, in horticultural practice, the suitable light intensity should be considered according to the cultivars of Saxifraga.