Response of photosynthetic characteristics of Vicia faba seedlings to volatile allelochemical stress from Chenopodium ambrosioides.
Pot experiment was conducted to evaluate the effect of volatile oil from an invasive plant, Chenopodium ambrosioides and its two main components α-terpene and cymene on the photosynthetic characteristics of Vicia faba seedlings. The results showed that the volatile oil treatment significantly reduced the net photosynthetic rate(Pn), stomatal conductance(Gs), transpiration rate(Tr), maximum photochemical efficiency(Fv/Fm), actual photochemical efficiency(ΦPS II)and total chlorophyll content. However, it increased the concentration of intercellular CO2(Ci), which was the dual effect of dose and time, and the effect of high dosed volatile oil treatment was irreversible. Compared with the control group, α-terpene treatment reduced Pn, Fv/Fm and ΦPS II, increased Ci, Gs and Tr, and all the parameters were gradually approaching to the control level after stopping treatment. However, the effects of cymene on photosynthetic characteristics of Vicia faba seedlings were not significant. These results suggested that the volatile allelochemical stress from Chenopodium ambrosioides on photosynthesis of receptor plants was due to the the synergistic effect of many allelochemicals, instead of a single component.