Effects of Aqueous extracts of 5 mangrove spp. on cabbage germination and hypocotyl growth of Kandelia candel

In petridish bioassay and pot culture, we assessed the allelopathic potential of five mangrove tree spp. (Avicennia marina (Forsk.) Vierh., Aegiceras corniculata (L.) Blanco, Kandelia candel (L.) Druce, Rhizophora stylosa Griff. and Bruguiera gymnorrhiza (L.) Lam.) on mid-successional mangrove specie (Kandelia candel (L.) Druce and cabbage. The aqueous extracts prepared from fresh leaves of mangrove trees and applied to test species, reduced their germination rate and seedlings growth. The allelopathic intensity of aqueous extracts on cabbage increased with the development of mangrove succession, but the response of K. candel to the extracts of five successional mangroves was variable. The mangrove spp. (R. stylosa, B. gymnorrhiza) drastically inhibited the growth of K. candel and may replace it in natural succession. The A. marina significantly inhibited the K. candel, but it is seldom replaced by K. candel in forest. Contrarily K. candel was less sensitive to extracts of A. corniculata (mangrove spp. naturally replaced by K. candel). Our results suggested that allelopathy may be one of the major driving forces regulating the mangrove forest succession.