《植物生理学报》 2018, 54(6): 973-982
通信作者：邱念伟；E-mail: nianweiqiu@163.com, jianweigao3@qq.com
摘 要：
为系统研究缺钙对大白菜幼苗生长的影响, 本文采用水培法分析了不同缺钙程度下, 大白菜幼苗的生长、生化和光合指标的特征性变化。研究结果显示, 与对照Hoagland完全营养液的100% Ca (4 mmol·L-1 Ca2+)相比, 50% Ca (2 mmol·L-1 Ca2+)培养4周虽然没有显著抑制大白菜幼苗的生长和净光合速率(Pn), 但其叶绿素含量已显著下降; 随着缺钙程度的加重, 大白菜幼苗的整株鲜重和Pn逐渐下降, 叶片叶绿素a/b比值逐渐增大, 叶绿素含量和可溶性糖含量则呈先降低后增大的趋势。缺钙大白菜的叶绿素荧光动力学ΔVt和ΔWt曲线上最明显的特征是在100 ms处明显出现一个凹峰(G相); 此外在缺钙大白菜ΔWt曲线的K相上(300 μs)也出现了特征性的凹峰, 且随着缺钙程度的加重, 凹峰值下降。两处凹峰的出现说明缺钙导致供体侧电子供应相对减少, 但光反应中心的结构和功能未受影响。缺钙条件下, 大白菜叶片叶绿素荧光参数的主要特征是由于放氧复合体电子供应能力减弱, 导致到达最大荧光的时间(Tfm)显著延长, 单个反应中心的光化学效率(ABS/RC、TRo/RC、ETo/RC)下降, 质体醌库(Sm)相对增大。上述结果为了解缺钙对大白菜幼苗的胁迫效应和伤害机制以及大白菜缺钙的诊断提供了数据支撑。关键词：缺钙; 大白菜; 光合作用; 叶绿素荧光
收稿：2018-04-13 修定：2018-05-18
资助：国家自然科学基金(31471884)、中国博士后科学基金(2016-M592158)和国家大学生创新创业训练计划项目(2018-10446082)。
Corresponding author: QIU Nian-Wei; E-mail: nianweiqiu@163.com, jianweigao3@qq.com
Abstract:
To systematically investigate the effects of calcium deficiency on the growth of Chinese cabbage, the characteristic changes of growth, biochemical, and photosynthetic indexes of Chinese cabbage seedlings under calcium deficiency were analyzed using a solution culture method. The results showed that 50% Ca (2 mmol·L-1 Ca2+) had no significant inhibition on the growth and net photosynthetic rate (Pn) during a 4-week treatment compared with the control (100% Ca: 4 mmol·L-1 Ca2+ in Hoagland’s nutrient solution), while its chlorophyll content was significantly lower than that of the control. With the aggravation of calcium deficiency, the fresh weight of the whole plant and Pn decreased gradually, and the ratio of chlorophyll a/b increased gradually. However, the chlorophyll content and soluble sugar content decreased at first and then increased. The most obvious feature on the chlorophyll fluorescence ΔVt and ΔWt curve of calcium-deficient cabbage was a clear concave peak at 100 ms (G-phase). In addition, a characteristic concave peak appeared at the K phase of the ΔWt curve of the calcium-deficient seedlings, and the concave peak value decreased with the aggravation of calcium deficiency. The two concave peaks at the K phase and G-phase indicated that calcium deficiency led to a relative decrease in electron supply on the donor side, but the structure and function of the reaction center were not affected. Under calcium deficient condition, the main feature of the chlorophyll fluorescence parameters was the weakening of the electron-supply capacity of the oxygen-evolving complex, which led to a significant extension of the time to reach maximal fluorescence intensity Fm (Tfm), a decreased photochemical efficiency of a single reaction center (ABS/RC, TRo/RC, ETo/RC), and a relatively larger plastoquinone pool. Taken together, this study contributes to our understanding of the effects of calcium deficiency on Chinese cabbage, and provides valuable information for the diagnosis of calcium deficiency of Chinese cabbage.Key words: calcium deficiency; Chinese cabbage; photosynthesis; chlorophyll fluorescence
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