Allelopathic Effects Of Root Exudates And Endophytic Fungi Ferments Of Bamboo

Bamboos, especially monopodial and amphipodial bamboo, have strong activity of invasion, which may be associated with alleloopathic activity of root exudates and endophytic fungi ferments. This study collected root exudates of Phyllostachys praecox(representative of monopodial bamboos) and ferments of Aspergillus sp.from Pleioblastus amarus(representative of amphipodial bamboos), and evaluated their allelopathic activity. Column chromatography and variety of modern spectroscopic techniques were used to identify compounds, and allelopathic activities were evaluated by the assay of seedling growth. The results were as following:For the allelopathic activity of root exudates, germination rate of rape seed was negatively correlated with the concentration of petroleum ether and ethyl acetate phase. When the concentration reached 10 g/L, the ethyl acetate phase could significantly lower the germination rate of rape to 0.03, which had no significant difference with positive control of glyphosate. Petroleum ether phase promoted seeding growth of both rape and radish, which was positively correlated with concentration. The RI values of rape root, rape shoot, radish root and radish shoot were 0.43, 0.47, 0.77; 0.19, 0.24, 0.40; 0.34, 0.51, 0.76; and 0.22, 0.32, 0.43, when petroleum ether phase concentrations were at 0.1 g/L, 1.0 g/L, 10 g/L, respectively. The growth of rape seedlings were promoted(RI>0), while the growth of radish shoots were inhibited when treated with different concentration of ethyl acetate phase. The intensity of inhibition was negatively correlated with concentration, which showed that there were allelochemicals in root exudates of Phyllostachys praecox.Five compounds were found in ferments of Aspergillus sp. from Pleioblastus amarus.The chemical structures of these substances were determined as chaetominine(1),(+)-alantrypinone(2), questin(3), isorhodoptilometrin(4), and 4-hydroxybenzaldehyde(5).All the determined compounds inhibited the germination of radish in a dose-dependent manner. When concentration reached 10mg/L, all the compounds inhibited the germination of radish and wheat(germination rate was 0 and RI was-1) more significantly than positive control of glyphosate. At low concentration(1.25 mg/L), compound 2, 3, 4 and 5 inhibited germination rate of radish more significantly than of glyphosate. Compound 2(+)-Alantrypinone could significant inhibite the growth of radish seedling. Different concentrations of questin(3) could significantly inhibit seedling growth of radish, with the RI value being-0.15,-0.16,-0.42,-1,-1(wheat root) and-0.53,-0.63,-0.75,-1,-1(wheat shoot), respectively.