岩溶地区典型蕨类植物卷柏根系分泌有机酸特征

岩溶地区土壤中Ca²⁺浓度普遍较高,探明植物对高钙环境的适生机制是实现岩溶地区植被恢复的重要基础。以岩溶地区先锋植物卷柏(Selaginella tamariscina)为研究对象,以添加Ca(NO₃)₂的方式,设置0、5、30、70、100、200、300 mmol·L^-1的Ca²⁺浓度梯度,采用砂培方式模拟岩溶地区的钙环境,利用气相色谱—质谱联用仪按照相似度达90%分析检测有机酸组成,分析高钙环境对植物根系分泌物的影响。研究结果表明:Ca²⁺浓度变化过程中,植物根系分泌有机酸中稳定存在的成分为棕榈酸、油酸、硬脂酸;在缺乏Ca²⁺的情况下,植物会分泌肉豆蔻酸、正十五烷酸等低浓度有机酸,并提高3种稳定有机酸的质量分数;在高钙环境下,根系分泌有机酸的种类会减少,3种稳定有机酸的质量分数也下降,但当Ca²⁺浓度达到100 mmol·L^-1后3种稳定有机酸的质量分数变化幅度趋于稳定;在高钙环境下,岩溶地区的先锋植物卷柏根系分泌有机酸质量分数相对降低,但能保持在一个稳定范围内,是根系分泌有机酸对高钙环境的适应机制。

Characteristics of Organic Acid Secretion by Roots of Typical Ferns Selaginella tamariscina in Karst Area

The content of Ca²⁺ in the soil in karst areas is generally high, and it is an important basis for vegetation restoration in karst areas to find out the mechanism of plant adaptation to the high-calcium environment. To explore high calcium environment on the influence of plant roots secretion, pioneer plant in karst region, taking Selaginella tamariscina as the research object, by adding Ca(NO₃)₂ of 0, 5, 30, 70, 100, 200 and 300 mmol·L^-1 to simulate calcium environment in karst region, the sand culture method simulation, we used gas chromatography-mass spectrometry instrument according to the similarity analysis to detect organic acids 90%. During the change of Ca²⁺ concentration, palmitic acid, oleic acid and stearic acid were stable components in the organic acids secreted by plant roots. In the absence of Ca²⁺, plants secrete low concentrations of organic acids such as myristic acid and n-pentadecanoic acid, and increase the content of three stable organic acids. Under high calcium stress, the types of organic acids secreted by roots decreased and the contents of the three stable organic acids also decreased. However, when the Ca²⁺ concentration reached 100 mmol·L^-1, the contents of the three stable organic acids tended to be stable. Under high calcium stress, the content of organic acid excudate by the root system of the pioneer plant S. tamariscina in karst area was relatively reduced, but it remained in a stable range, which was the adaptation mechanism of organic acid secreted by the root system to the high calcium stress.