The Effect of Exogenous Calcium on Respiratory Metabolism in Malus Baccata Borkh. Roots under Temperature Treatment

摘要

In order to study the effects of exogenous calcium on respiratory metabolism in Malus baccata Borkh. roots during temperature serious fluctuation (increased from 5°C to 20°C, and then decreased tol0°C and 0°C), 15-leaf seedlings were used as materials, treated with five concentrations of CaCl2 (0.5% CaCl2, 1% CaCl2, 1.5% CaCl2, 2% CaCl2 and 5% CaCl2). Different calcium concentrations showed different effects on total respiratory rates of roots during temperature serious fluctuation. Compared with control, 2% CaCI2 presented the most prominent effect in enhancing the respiratory rates of TCA and PPP to total respiratory rate, by up-regulating the activities of key enzymes (IDH in TCA, G-6-PDH in PPP) during the decrease of temperature from 20°C to 0°C. However, 5% CaCl2 had the negative effect on respiratory metabolism by down-regulating key enzymes in metabolism pathways. In conclusion, 2% CaCl2 showed better enhancing effect on respiratory metabolism than that of 0.5% and 1.0% CaCl2 during temperature decreasing, while higher calcium concentration (5%) had inhibiting effect at the same treating stage.