加拿大一枝黄花和小飞蓬叶浸提液对大豆幼苗生长的复合化感效应

加拿大一枝黄花(Solidago canadensis)和小飞蓬(Conyza canadensis)常共同入侵至同一农田生态系统。探究了两者对大豆幼苗生长的复合化感作用。加拿大一枝黄花叶浸提液显著抑制大豆幼苗地上生物量。而小飞蓬叶浸提液也明显抑制大豆幼苗地上生物量(未达到显著水平)。与对照处理相比,两者复合叶浸提液处理未显著影响大豆幼苗地上生物量。两者复合叶浸提液处理下大豆幼苗地上生物量显著大于加拿大一枝黄花叶浸提液单一处理,同时也大于小飞蓬叶浸提液单一处理(未达到显著水平)。两者叶浸提液单一处理均明显降低大豆幼苗株高(未达到显著水平)。与对照处理相比,两者复合叶浸提液处理未显著影响大豆幼苗株高。两者复合叶浸提液处理下大豆幼苗株高明显大于两者叶浸提液单一处理(未达到显著水平)。因此,两者叶浸提液对大豆幼苗的生长均具有一定程度的抑制效应,且加拿大一枝黄花叶浸提液对大豆幼苗产生的化感作用(尤其是地上生物量)明显大于小飞蓬。两者复合化感作用明显低于两者单一化感作用,尤其是两者对大豆幼苗地上生物量的复合化感作用显著低于加拿大一枝黄花的单一化感作用。所以,化感效应可能在两者共同入侵(即两者复合作用)进程中所起的贡献低于在两者单一入侵进程中所起的作用。

Synergistic Allelopathic Effects of Solidago canadensis and Conyza canadensis on Seedling Growth of Glycine max

The co-invasion of Solidago canadensis and Conyza canadensis may occur in the same agricultural ecosystem usually. This study aims to determine the synergistic allelopathic effects of the two species on seedling growth of Glycine max. Results showed that single leaf extracts of S. canadensis significantly reduced the aboveground biomass of G. max seedling. Single leaf extracts of C. canadensis also reduced the aboveground biomass of G. max seedling obviously but did not reach the significant level. The mixed leaf extracts of the two species did not affect the aboveground biomass of G. max seedling significantly compared with the control. The aboveground biomass of G. max seedling under the mixed leaf extracts of the two species was significantly higher than that under single leaf extracts of S. canadensis but close to that under single leaf extracts of C. canadensis. Single leaf extracts of the two species all reduced the height of G. max seedling but the change was not significant. The mixed leaf extracts of the two species did not affect the height of G. max seedling significantly compared with the control. The height of G. max seedling under the mixed leaf extracts of the two species was higher than that under single leaf extracts of the two species although not at significant level. Thus, the leaf extracts of the two species exhibit allelopathic effects on seedling growth of Glycine max, and S. canadensis triggered more allelopathic effects on seedling growth of Glycine max than C. canadensis. Meanwhile, the allelopathic effect of the mixed leaf extracts of the two species was lower than that of single leaf extracts of the two species. Especially, the effect of the mixed leaf extracts of the two species on the aboveground biomass of G. max seedling was significantly lower than that of single leaf extracts of S. canadensis. Thus, the allelopathic effects of S. canadensis and C. canadensis on the growth of native seedling might play a more important role in their single invasion process than in their co-invasion process.