Studies on allelopathic potential of an important agroforestry species

Abstract

The phytotoxicity of Leucaena leucocephala leaf leachate was evaluated using rice and a few tree species associated with agroforestry systems as test crops. The phytotoxicity of Leucaena leaf leachate differed according to the amount of mimosine present in it. The Leucaena leaf exposed to sunlight lost over 33–42% of total mimosine content. Among the three successive leaf extracts tested, the first extract showed an inhibitory effect, while the third extract exhibited a stimulatory effect on rice radicle growth. The effect of a second successive extract was inconsistent. The germination, radicle and root growth of Casuarina equisetifolia was severely inhibited by the 1% aqueous leaf extract from the Leucaena cultivar ‘K 8’. However, the germination and radicle growth of different cultivars of Leucaena were least affected, and the allelopathic inhibition of Pongamia pinnata was of the second order. Among the tree species studied, Acacia nilotica was most tolerant to the phytotoxic effect of Leucaena leaf leachate.