Allelopathy in some spontaneous and cultivated species

Abstract

Cucumber growth was inhibited by volatile and water soluble compounds occurring in leaves of Cistus salvifolius, Foeniculum vulgare, Myrtus communis and Rosmarinus officinalis but germination was never affected. R. officinalis shows some evidence of being the strongest inhibitor with both water soluble and volatile components while F. vulgare seems to contain more volatile-compounds. It is suggested that water soluble compounds are more inhibitory than volatiles and can play an important role in dry climates strengthening volatile activity when seed emergence is stimulated by rainfall. Open air experiments with pots in sand or soil involving perennial ryegrass, lucerne, subterranean clover (as donors and receivers) and Oxalis pes-caprae (only as donor) showed no sign of allelopathic activity by root exudates between young plants of these species. In laboratory experiments carried out simultaneously, some evidence was found of the change in the nature of root exudates.