Effects of different calcium concentrations on the growth and physiological characteristics of Dalbergia odorifera under low temperatures

Dalbergia odorifera T. Chen was used to study the effects of different concentrations of exogenous Ca²⁺ on seedling growth and physiological characteristics under different artificial temperature conditions. Significant effects were found on stem height, leaf length, P_n, G_s, T_r, and photosynthetic pigment content under different concentrations of Ca²⁺ at normal temperature. However, limited effects were found on the relative water content and dew point water potential of leaves, relative conductivity, MDA, and soluble protein content. The optimum Ca²⁺ concentration to improve plant growth was 5 mmol/L. In addition, stem height, leaf length, P_n, G_s, T_r, WUE, content of photosynthetic pigment, relative water content, dew point water potential, relative conductivity, MDA, and soluble protein content were significantly affected by cold stress. These negative effects could be alleviated by applying exogenous Ca²⁺, with the optimal Ca²⁺ concentration again found to be 5 mmol/L, followed by 10, 15, and 2.5 mmol/L under normal temperature and cold stress. The results of this study provide scientific guidance in regard to the adaptation of D. odorifera to cold stress and its cultivation in low temperature regions of subtropical areas.