不同钙离子浓度对喜钙和嫌钙型金花茶光合及生理指标的影响

Effects of different calcium ion concentrations on photosynthetic and physiological indexes of calcicole-type and calcifuge-type golden Camellia

关键词:  金花茶, 喜钙, 嫌钙, 光合, 荧光, 生理

Key words:  golden Camellia, calcicole, calcifuge, photosynthesis, fluorescence, physiology

摘要:

为探讨喜钙型金花茶对高钙环境的生理适应机制以及嫌钙型金花茶的避钙机理,该文采用砂培法,分别以两种喜钙型金花茶 [直脉金花茶(Camellia multipetala)、柠檬金花茶(C. limonia)]和两种嫌钙型金花茶 [金花茶(C. nitidissima)、东兴金花茶(C. tunghinensis)]的幼苗为材料,用不同浓度(设为5、25、50、100 mmol·L^-1)的钙离子(Ca²⁺)营养液进行培养,研究其对两种不同类型金花茶的光合及生理指标的影响。结果表明:两种嫌钙型金花茶的净光合速率(P_n)、气孔导度(G_s)、实际光化学效率(ΦPSⅡ)、电子传递效率(ETR)、叶绿素a(Chl a)、叶绿素b(Chl b)、叶绿素总量[(Chl(a+b)]均随Ca²⁺浓度的升高而降低,表明高钙环境降低了嫌钙型金花茶的光合能力; 喜钙型金花茶的这些指标在不同Ca²⁺浓度下无显著变化,高钙环境未影响其光合作用的正常进行。嫌钙型金花茶叶片丙二醛含量和PSⅡ最大光化学效率(F_v/F_m)在高钙环境下未有显著变化,表明其光合膜系统还未受到伤害。随着Ca²⁺浓度的升高,嫌钙型金花茶叶片脯氨酸含量显著增加,而可溶性糖含量变化却不大; 喜钙型金花茶在不同Ca²⁺浓度下脯氨酸和可溶性糖含量的变化均不明显,但其可溶性糖含量却明显高于嫌钙型金花茶。喜钙型金花茶对外界钙离子浓度的变化不敏感,其适应高钙的生理机制可能与叶片较高的可溶性糖含量有关; 而嫌钙型金花茶对高钙环境的适应性较差,这可能是其不能在钙质土上生长的主要原因。

Abstract:

In order to explore the physiological adaptation mechanism of calcicole-type golden Camellia to high calciumion environment and analyze the main reasons that the calcifuge-type golden Camellia can not grow on calcareous soil,a pot experiment was conducted with two species of calcicole-type golden Camellia(Camellia multipetala and C. limonia)and two species of calcifuge-type golden Camellia(C. nitidissima and C. tunghinensis)seedlings. To exclude the influences from other confounding factors, each pot was filled with sand instead of soil. The seedlings were treated with four Ca levels, 5, 25, 50, 100 mmol·L^-1. The photosynthetic and physiological indexes of two different types of golden Camellia were measured. The results were as follows: The net photosynthetic rate(P_n), stomatal conductance(G_s), actual photochemical efficiency(ΦPS Ⅱ), electron transfer efficiency(ETR), Chl a, Chl b and total Chl of the calcifuge-type golden Camellia decreased with the increase of Ca²⁺ concentration, which indicates that the photosynthetic capacity of these two species decreased under the high calciumion environment; While these indexes in the calcicole-type golden Camellia did not change significantly under different Ca²⁺ concentrations, indicating high calciumion environment did not affect its normal photosynthesis. The content of malondialdehyde and the PS Ⅱ maximum photochemical efficiency(F_v/F_m)of the calcifuge-type golden Camellia did not change significantly under high calciumion environment, indicating that its photosynthetic membrane system has not been damaged. With the increase of Ca²⁺ concentration, the proline content of the calcifuge-type golden Camellia increased significantly, while the soluble sugar content did not change much; The proline and soluble sugar content in calcicole-type golden Camellia were not obviously changed under different Ca²⁺ concentration, but the soluble sugar content in calcicole-type golden Camellia was significantly higher than that of the calcifuge-type golden Camellia. Calcicole-type golden Camellia were not sensitive to the external calciumion concentration, its physiological mechanism of adaptation to high calciumion may be related to the higher content of soluble sugar in leaves; However, the adaptability of calcifuge-type Camellia to high calciumion environment was poor, which may be the main reason for its inability to grow on calcareous soil.