Allelopathic effects of Eupatorium adenophorum on five species of the family Gesneriaceae

Eupatorium adenophorum (Compositae),a highly invasive plant in southwestern China,has increasingly invaded the habitats of the gesneriaceous plants. All species of Gesneriaceae in China have been listed in China’s Red List and some of them have been categorized as the National Key Protected Species. To examine the possible allelopathic effect of E. adenophorum on Gesneriaceae,five species in three genera of Gesneriaceae (Chirita spinulosa, C. heterotricha, C. liboensis, Aeschynanthus acuminatus, and Titanotrichum oldhamii) were treated with three parts of E. adenophorum, i.e.,aqueous root, stem, and leaf extracts (8%), respectively. The results indicated that aqueous leaf extracts of E. adenophorum had very different impacts on C. spinulosa, C. liboensis and C. heterotricha, of which it was the most obvious on C. spinulosa. Seedling growth of C. spinulosa were totally inhibited when aqueous leaf extracts 2.4%, 3.2% and 4.0%. The aqueous stem extracts of E. adenophorum showed some impacts on T. oldhamii. Seedling growth of T. oldhamii were inhibited 40% when the stem extracts of E. adenophorum was 1.6% . Aqueous leaf and stem extracts of E. adenophorum had little effect on seedling growth of A. acuminatus. However,aqueous root extracts of E. adenophorum also had no significant suppression on these five species. Therefore,our experiments confirmed allelopathy of E. adenophorum on Chirita and Titanotrichum but not so much on Aeschynanthus. The gesneriaceous species on rocks seemed more susceptible to allelopathy of E. adenophorum than their allied species on trees.