Response of leaf functional traits of Fraxinus malacophylla seedlings to calcium

Key words: 
• Fraxinus malacophylla /
• calcium /
• leaf shape /
• physiological characteristics

Abstract:   Objective  This study, with an investigation of the effects of different calcium concentrations on leaf morphological indexes, chlorophyll content and enzyme activity of Fraxinus malacophylla seedlings, is aimed to better understand the growth and development of F. malacophylla seedlings under different calcium concentrations so as to further explore the environmental adaptability of F. malacophylla seedlings when treated with different calcium concentrations.   Method  With 1-year-old F. malacophylla seedlings selected as the materials, a research was conducted of the effects of 0 (ck), 25, 50, 75 mmol·L⁻¹ calcium treatments on their leaf morphological indexes, chlorophyll content and enzyme activity.   Result  Different calcium concentrations had different effects on leaf morphological indexes, chlorophyll content and enzyme activity of F. malacophylla seedlings. When treated with different calcium concentrations, with the increase of calcium concentration, all indexes of leaf morphology and structure of F. malacophylla seedlings increased first and then decreased, except for specific leaf length and specific leaf area which increased, whereas leaf number, leaf biomass, specific leaf length, specific leaf area, chlorophyll content, catalase activity and peroxidase activity were significantly different from those in control (P＜0.05). When the calcium concentration was more than 50 mmol·L⁻¹, the treatment had no inhibitory effect on F. malacophylla seedlings, indicating that F. malacophylla seedlings responded favorably to medium-low calcium concentration. When the concentration of calcium was 75 mmol·L⁻¹, it inhibited the growth and development of F. malacophylla seedlings, implying that too high a calcium concentration can inhibit the growth of F. malacophylla seedlings. When the calcium concentration was 50 mmol·L⁻¹, the leaf morphological indexes, leaf related indexes, chlorophyll content and enzyme activity of F. malacophylla seedlings reached the maximum, and the growth and development of F. malacophylla seedlings were the best.   Conclusion  The optimal calcium concentration for the growth of F. malacophylla seedlings is 50 mmol·L⁻¹ since too high a calcium concentration inhibits the growth, leaf chlorophyll mass fraction and leaf enzyme activity of F. malacophylla seedlings. [Ch, 1 fig. 2 tab. 28 ref.]