Allelopathy Effects Of Poisonous Plant In The "Black Soil Land" Of Tibetan-plateau And Its Inhibitory Mechanism To Pedicularis Kansuensis

The poisonous plant spread grassland in Tibetan-plateau is harmful to ecological and produce function, and how to control the poisonous plant is the important task for "black soil land" treatment. The phenomenon of Pedicularis kansuensis intrude sown grassland which is "black soil land" rebuilding grassland ago was the main reason to led to speedy waning of sown grassland. This study based on chemical ecological mechanism of plant allelopathy, by testing the allelopathic relationship between the Pedicularis kansuensis, Oxytropis ochrocephala, Stellera chamaejasme, Ligularia virgaurea, Elsholtzia var. densa and Artemisia nanschanica separately, sieving the species and find effective compounds for control the Pedicularis kansuensis, but the compounds are secure for sown grassland, and provide scientific basic to develop special biological hibicides of Pedicularis kansuensis.The bioactivity of aqueous extract of the air dried plant (branches, leaves and roots, for 48 hr), organic extracts (branches and leaves) were evaluated on the growth of Pedicularis kansuensis and Elymus nutans. Further analyses and identification of allelochemicals were conducted by gas chromatography-mass spectrometry on the most toxic fraction.Followings were the results:â‘ The vegetation composition characteristics, physical and chemical features of soil in the Aconitum pendulum, Stellera chamaejasme, Ligularia virgaurea, Oxytropis ochrocephala which were widely distributed in Tibetan-plateau had few differences.â‘¡With the concentration increasing, the dissolve solutions of Oxytropis ochrocephala, Stellera chamaejasme, Ligularia virgaurea, Elsholtzia var. densa and Artemisia nanschanica had increased allelopathy effects to Pedicularis kansuensis and its neighbor Elymus nutans. The inhibitory effects of leaves and roots dissolve solutions were stronger than the water extraction of stems when the same vegetation was in the same concentration. The leaves of Artemisia nanschanica had stronger inhibitory effects to seedlings of Pedicularis kansuensis than other poisonous plant when the concentration was 25g/L; however, when the concentration was 100 g/L, they had lethal effects to seeds germination and seedling growth of Pedicularis kansuensis.â‘¢The seedlings of Elymus nutans G. had better resistance to dissolve solutions of leaves of Artemisia nanschanica, so Artemisia nanschanica could be used as the biological material of herbicides to Pedicularis kansuensis.â‘£The ethyl acetate extracts of the Artemisia nanschanica aerial part had a remarkable effect to seeds germination and seedling growth of Pedicularis kansuensis (P<0.05). Three target compounds aromadendrene oxide (C15H24O), isoaromadendrene epoxide(C15H24O) and 6-(3-hydroxyprop-1-en-2-yl)-4,8a-dimethyl-2,4a,5,6,7,8-hexahydro-1H-naphthalen-2-ol(C15H24O2) were obtained by separation of chromatographic column and detection of mass spectrometry, and they were all sesquiterenes, had allelopathy synergistic effects and could be used as the herbicides to Pedicularis kansuensis.