Allelopathic potential of sunflower. II. Allelopathic activity of plants compounds released in environment

摘要

This paper is the second of two parts describing the allelopathic potential of sunflower. This study aimed to: (i) determine the allelopathic activity of volatiles,root exudates, leachates and extracts of sunflower (Helianthus annuus L.) cv. 'Ogrodowy' and (ii) check whether soil after sunflower cultivation exhibit allelopathic activity. Acceptors of the allelochemicals were seeds and seedlings of mustard (Sinapisalba L.) cv. 'Nakielska'. Allelopathic compounds of sunflower origin, irrespective of their mechanism of release mostly, exerted the inhibitory allelopathic effects on the acceptor plants. The sunflower leaf volatiles, extracts or leachates reduced the germination of mustard. Allelochemicals contained in the shoot and in the seedling exudates had negative effects on seedlings of acceptor plants (weak, stunted and had low fresh weight). The inhibitory effects were greater for volatiles released by chopped than intact leaves and for the allelochemicals extracted than leached from fresh leaves. The inhibitory effects were greater in combined exudates and volatiles aprowth of mustard plants was strongly inhibited by some compounds that were present in thesoil fromthe preceding sunflower crop.