外来入侵植物的氮代谢及其土壤氮特征

Characteristics of Nitrogen Metabolism and Soil Nitrogen of Invasive Plants

摘要:

研究了4种外来入侵植物(五爪金龙、南美蟛蜞菊、金腰箭和马缨丹)和1种本地植物鸡矢藤(对照)的氮代谢及其土壤氮特征。结果表明：外来入侵植物的组织硝酸还原酶活性、根际土壤NH4-N、NO3-N含量、蛋白酶活性和脲酶活性均较高，分别为鸡矢藤的1.65~4.34、1.56~2.15、1.72~3.11、1.43~3.23和1.41~3.33倍，而植物组织硝态氮含量则较低，仅为鸡矢藤的17.5%~50.6%。相关分析表明：植物组织硝酸还原酶活性与根际土壤总氮、NH4-N、NO3-N含量呈显著正相关(P<0.05)，与蛋白酶活性和脲酶活性呈极显著正相关(P<0.01)。这说明，外来植物入侵使土壤氮代谢加快，氮的生物有效性增强，氮同化能力提高，并且较好地将植物体氮素代谢与土壤氮素代谢协调起来。因此，较强的氮素同化能力与加速土壤氮素的转化可能是植物成功入侵的重要机制之一。

Abstract:

The characteristics of nitrogen metabolism and soil nitrogen of four invasive plants (Ipomoea cairica, Wedelia trilobata, Synedrella nodiflora, Lantana camara) and one native plant (Paederia scandens, control plant) had been studied. The results showed that the activity of nitrate reductase in invasive plant tissue, the contents of NH4-N and NO3-N and the activities of protease and urease in their rhizosphere soil were higher than those of Paederia scandens by 1.65~4.34 times, 1.56~2.15 times, 1.72~3.11 times, 1.43~3.23 times and 1.41~3.33 times, respectively. But the nitrate content in invasive plant tissue fell to 17.5%~50.6% that of Paederia scandens. Furthermore, the correlation analysis indicated that the activity of nitrate reductase in invasive plant tissue was positively and significantly related to total nitrogen, NH4-N, NO3-N and the activities of protease and urease in their rhizosphere soil. The invasion of exotic plants speeded up nitrogen metabolism, enhanced nitrogen bioavailability, improved the efficiency of nitrogen assimilation, and coordinated plant nitrogen metabolism with soil nitrogen metabolism. All these benefited their growth when invasive plants competed against native ones for nitrogen, which might be a contributing factor to their successful invasion.