Effect of enhanced ultraviolet-B on allelopathic potential of Zanthoxylum bungeanum

The effect of enhanced ultraviolet-B on allelopathic potential of Zanthoxylum bungeanum was investigated. A significant inhibitory effect on germination rate of crop seeds under bioassay was observed at 25 g l⁻¹ and 50 g l⁻¹ by extracts from Zanthoxylum leaf both treated with enhanced ultraviolet-B radiation and untreated control. Medicago sativa and lettuce were more sensitive than radish to the extract from Zanthoxylum leaf treated with enhanced UV-B radiation, as the germination rates of M. sativa and lettuce were significantly reduced compared to control at 25 g l⁻¹ and 50 g l⁻¹, and so did alfalfa at 12.5 g l⁻¹. However, as for radish (Raphanus sativus) there was no significant reduction in germination rate at any concentration under bioassay compared to control. Content of UV-B absorbing compounds and total phenols in Zanthoxylum seedlings responded positively to enhanced UV-B radiation. The results suggest that the allelopathic potential of Z. bungeanum was generally improved under enhanced UV-B radiation.