Allelopathic effects of VOCs of Artemisia frigida Willd. on the regeneration of pasture grasses in Inner Mongolia

Abstract

Grassland of Inner Mongolia, the main grassland region of China and part of the Eurasia Steppe that stretches from East China to Hungary, is among the most seriously degraded grasslands in China. Previous studies on causes of grassland degradation in this region focused primarily on anthropogenic activities, such as rapid development, ranching, agricultural activities, and mining for mineral resources. Few studies have examined plant interactions during the processes of grassland degradation. In this study, using the thermal-desorption cold trap/gas chromatography/mass spectrometer technique (TCT/GC/MS) we examined the effects of volatile organic compounds (VOCs) of Artemisia frigida on the seed germination and seedling growth of 4 common grass species, Melitotus suaveolens, Sorghum sudanense, Elymus dahuricus and Agropyron cristatum, in the Inner Mongolian pastures. We found that the major constituents of the VOCs from natural A. frigida were 1,8-cineole, camphene, (E)-3-hexen-1-ol acetate, α-terpineol, β-Terpineol, (R)-(−)-p-Menth-1-en-4-ol, p-cymene, and camphor, whose relative content accounted for 96.0% of the 22 compounds identified for natural A. frigida. The content and amount of these VOCs varied when A. frigida was damaged artificially. The VOCs from A. frigida significantly decreased the seed germination and seedling growth of all the tested plant species. Our finding that artificially damaged plants of A. frigida released different types and amount of VOCs from undamaged ones under laboratory conditions indicate that grazing activity on natural pastures may influence the type and amount of VOCs released from A. frigida. However, more research is needed under field conditions to draw a conclusion if grazing activity has similar impacts on release of VOCs as under laboratory conditions.