Allelopathic effects of Psychotria viridis Ruiz & Pavon on the germination and initial growth of Lactuca sativa L.

The effects of aqueous and ethanol extracts and leaf fractions of Psychotria viridis Ruiz & Pavon (chacrona) at different concentrations on the germination and initial growth of Lactuca sativa L. were tested, and the phenolic and flavonoid compounds of these extracts and fractions were assessed. The bioassays consisted of the following treatments: crude aqueous extract (CAE) at 25, 50, 75 and 100% concentration, crude ethanol extract (CEE) and ethyl acetate, dichloromethane and methanol fractions at 6.25, 12.5, 25, 50 and 100% concentration and a control group. All treatments consisted of five replicates. The CAE, CEE and the ethyl acetate fraction of P. viridis caused both positive and negative effects on the seeds and seedlings of L. sativa. By contrast, the dichloromethane and methanol fractions only caused negative effects on L. sativa. The following compounds were identified in the extracts and fractions: gallic acid, chlorogenic acid, caffeic acid, ellagic acid, catechin, orientin, vitexin, quercetin, apigenin, rutin and luteolin, and the presence of the alkaloid N,N-dimethyltryptamine (DMT) has also been reported in the literature. P. viridis had allelopathic effects in all types of plant extracts and fractions tested, and one of these compounds or their combined action may account for these effects.