模拟酸雨对3种菊科入侵植物光合特性的影响

研究了模拟酸雨(pH值分别为2.5、4.5和5.6)对3种菊科入侵植物--三裂叶蟛蜞菊(Wedelia trilobata)、薇甘菊(Mikania micrantha)和飞机草(Chromolaena odoratum)光合生理生态特性的影响。结果表明, 重度酸雨(pH值2.5)对3种入侵植物叶片均造成可见伤害, 其中飞机草受害最严重, 薇甘菊次之, 三裂叶蟛蜞菊受害最轻。同时, 3种入侵植物对酸雨胁迫表现出不同的光合响应, 随着酸雨pH值的降低, 飞机草和薇甘菊叶片叶绿素含量均有所下降, 其净光合速率(P_n)受到抑制, 而三裂叶蟛蜞菊叶片叶绿素含量变化不大, 其P_n值呈上升趋势。酸雨处理下, 3种入侵植物的细胞膜透性、丙二醛含量(MDA)及超氧化物歧化酶(SOD)和过氧化物酶(POD)活性均有不同程度的增加, 表明它们受到酸雨的胁迫并具有一定的抵抗力。其中, 经pH值2.5酸雨处理后的三裂叶蟛蜞菊叶片SOD活性增幅最大, 其对酸雨胁迫的反应最为迅速。上述研究结果表明, 三裂叶蟛蜞菊对酸雨胁迫的耐受性和适应性均高于飞机草和薇甘菊。在酸雨污染日趋严重的今天, 应对其危害予以高度重视。

Effect of Simulated Acid Rain on Gas Exchanges of Three Compositae Invasive Plants

We examined the effect of simulated acid rain (pH 2.5, 4.5, 5.6) on gas exchanges of 3 compositae invasive plants (Wedelia trilobata, Mikania micrantha and Chromolaena odoratum). Leaves of the 3 invasive plants showed injury under severe acid rain stress (pH 2.5). The order of the injury degree was C. odoratum > M. micrantha > W. trilobata. The 3 invasive plants showed different photosynthetic responses to simulated acid rain stress. The chlorophyll (Chl) content of C. odoratum and M. micrantha was reduced with decreasing pH, and thus the net photosynthetic rate (P_n) was inhibited, with no difference for W. trilobata. Instead, its P_n increased, although not significantly. Under acid rain treatment, membrane permeability, malondialdehyde content and superoxide dismutase (SOD) and peroxidase activity increased for all plants to varying degrees, which showed some resistance to acid rain. W. trilobata showed the greatest increase in SOD activity under pH 2.5, which suggests its fast response to acid rain stress. W. trilobata had stronger adaptability and tolerance to acid rain than the other 2 invasive plants and could be further investigated in light of increasing acid rain pollution.