叶面喷施钙素对光胁迫条件下烤烟光合生理特性的调控效应

以烤烟品种K326为供试材料开展土培盆栽试验,在人工气候室条件下设置3种光照强度,研究叶面喷施钙素对不同光照强度下烤烟叶片光合色素、气体交换参数、抗氧化酶活性、渗透调节物质及干物质积累的影响,探明外源钙对光胁迫条件下烤烟光合生理特性及抗氧化系统的调控作用。结果表明,喷施外源钙可以增加不同光照强度下烤烟叶片的叶绿素（Chla+b）及类胡萝卜素（Car）含量,Chla+b和Car含量的最高值分别出现在400~500μmol/(m²·s)低光（L1）和1500~1800μmol/(m²·s)高光（L3）处理。烤烟叶片的净光合速率（P_n）随光强增加而升高,但光能利用效率（LUE）以L1处理最高。增施外源钙后烤烟叶片的P_n、蒸腾速率（T_r）、气孔导度（G_s）以及LUE显著增加,且在L1与L3处理下LUE增加比例较高,分别比对照增加了3.83%~5.63%和4.65%~7.75%。高光喷钙处理的超氧化物歧化酶活性、过氧化物酶活性、可溶性糖含量以及干物质积累量最高,丙二醛含量最低。喷施外源钙可提高烟草叶片活性氧清除酶活性和渗透调节物质含量来保护光胁迫条件下光系统Ⅱ（PSⅡ）反应中心不受伤害,促进光合效率提高,有利于光合碳同化产物的积累。

Effects of Calcium by Foliage Spraying on Photosynthesis Physiology Characteristics of Flue-Cured Tobacco under Light Stress

The effects of the exogenous calcium on the photosynthetic pigments, gas exchange parameters, antioxidant enzyme activities, osmoregulation substances and dry matter accumulation of flue-cured tobacco were investigated with flue-cured tobacco variety K326 as experimental material. The soil-culture pot experiment was carried out under three light intensities in the artificial climate chamber in order to study the regulating effects of the exogenous calcium salts on the photosynthetic physiological characteristics and antioxidant system of flue-cured tobacco under light stress. The results showed that the contents of chlorophyll (Chla+b) and carotenoid (Car) in flue-cured tobacco leaves under different light intensities were increased by the application of exogenous calcium, and the highest values of Chla+b and Car respectively appeared in 400-500μmol/(m²·s) low light treatment (L1) and 1500-1800μmol/(m²·s) high light treatment (L3). With the increase of light intensity, the net photosynthetic rate (P_n) was increased, but the light energy utilization efficiency (LUE) of L1 treatment was the highest. The values of P_n, transpiration rate (T_r), stomatal conductance (G_s) and LUE were significantly increased by spraying exogenous calcium on flue-cured tobacco leaves,the increase proportion of LUE was higher under L1 and L3 treatments, increased by 3.83%-5.63% and 4.65%-7.75% compared with the control, respectively. The superoxide dismutase and peroxidase activities, the soluble sugar and dry matter accumulation contents were the highest under the condition of L3 treatment with exogenous calcium application, but the content of malonaldehyde was the lowest. Consequently, in order to protect the PSII reaction center under light stress, the exogenous calcium application enhanced the active oxygen scavenging enzyme activity and osmotic adjustment substance content, the photosynthetic efficiency of flue-cured tobacco could be effectively improved so that the photosynthetic carbon assimilation products could be promoted.