氮沉降对不同入侵程度加拿大一枝黄花化感作用的影响

为探究全球氮沉降影响外来植物入侵扩张的作用机制,该文通过受控模拟试验,以入侵植物加拿大一枝黄花(Solidago canadensis)为对象,研究了三种氮水平(N0、N5和N12)下五种不同入侵程度(种内及种间竞争)的加拿大一枝黄花凋落叶浸提液对本地植物莴苣(Lactuca sativa)种子萌发和幼苗生长化感作用的影响。结果表明:(1)N0、N5和N12处理下的不同入侵程度加拿大一枝黄花凋落叶浸提液均显著抑制莴苣的萌发和生长,其中N5土壤入侵初期(S1A3)处理浸提液的化感作用最显著,其发芽速度指数、发芽活力指数、根长、株高和叶长比对照分别降低了61%、79%、84%、68%和13%,此时凋落叶中的总酚和总黄酮含量最高,分别为0.48 mg·g^-1和1.50 mg·g^-1。(2)相同氮添加下,入侵程度对加拿大一枝黄花化感作用有显著影响,随着入侵程度的增加,加拿大一枝黄花化感作用显著减弱,入侵初期(S1A3)凋落叶化感作用显著高于入侵后期(S3A1)。(3)相同入侵程度下,氮添加对加拿大一枝黄花化感作用有显著影响,N5处理的加拿大一枝黄花化感作用比N0或N12处理显著增加。(4)氮添加与入侵程度有交互作用,两者共同作用显著影响了莴苣种子的综合化感作用。综上结果表明,氮沉降可能会增强入侵初期加拿大一枝黄花凋落叶对本地植物的化感抑制作用,进一步促进外来植物的成功入侵,为进一步研究加拿大一枝黄花的化感作用及生态防治提供了一定的理论参考。

Allelopathy of Solidago canadensis with different invasion degrees under nitrogen deposition

Increased global nitrogen deposition has been seen as a possible new driver for the expansion of many invasive plants. But its mechanism of action remains unclear. Therefore, this study aimed to examine the effects nitrogen deposition on the invasion degree of a worldwide clonal invasive weed Solidago canadensis. To conduct this research, three kinds of nitrogen levels(N0, N5 and N12)were set up to simulate different degrees of nitrogen deposition and five different competition levels(intraspecies and interspecies)through controlled simulation experiments to obtain S. canadensis litter. Then the allelopathy of the extract of the S. canadensis litter leaf on Lactuca sativa seeds was studied. The results were as followes:(1)Solidago canadensis litter of different invasion levels under N0, N5 and N12 nitrogen addition treatment significantly inhibited the germination and growth of Lactuca sativa. In addition, the allelopathic effect of the extract at the initial stage of invasion(S1A3)under the addition of N5 was the most significant, and its germination speed index, germination vitality index, root length, plant height, and leaf length were respectively reduced by 61%, 79%, 84%, 68% and 13% compared with the control. At this time, the total phenol and total flavonoid content in litter were 0.48 mg·g^-1and 1.50 mg·g^-1, respectively.(2)Under the same nitrogen addition, the degree of invasion had a significant effect on the allelopathic effect of Solidago canadensis. With the increase of the proportion of Artemisia argyi, the allelopathic effect of the extract significantly increased and the content of litter allelochemicals in the early invasion(S1A3)was significantly higher than that in the late invasion(S3A1).(3)When the invasion degree is the same, the allelopathic effect of N5 nitrogen addition treatment is significantly higher than that of N0 or N12 nitrogen addition treatment.(4)Nitrogen addition has an interaction with the degree of invasion and their combined effect significantly affects the allelopathic effect of Lactuca sativa seeds. It can be inferred that nitrogen deposition may enhance the allelopathic inhibition effect of Solidago canadensis litters on native plants and further promote the successful invasion of invasive plants. This study provides a theoretical reference for further research on the allelopathy and ecological control of S. canadensis.