Evaluation of the allelopathic effects of the aqueous extract of dried leaves of Psidium guajava L. on the germination and initial development of Phaseolus vulgaris L.

Abstract

Allelopathy is a natural phenomenon that consists of the release of secondary metabolites from plants, and can have beneficial or harmful effects on other plants. There is great potential to incorporate allelopathy into more sustainable agricultural practices; however, in agroforestry systems, this phenomenon needs to be evaluated in the proposal of consortia between different plant species to avoid losses. Therefore, the objective of this work was to conduct an initial study to evaluate, under laboratory conditions, the allelopathic effects of the aqueous extract of dried leaves of Psidium guajava L. at different concentrations on the germination process and initial development of Phaseolus vulgaris L. seedlings. The variables evaluated were percentage, average time, speed index, relative frequency and synchronization index of the germination process, percentage of normal and abnormal seedlings, average length and dry mass of the shoot and root of seedlings, and lipid peroxidation levels of the roots of P. vulgaris. The data were subjected to analysis of variance and the means were compared by Tukey's test at 5% probability. The main results observed were the decrease in the percentage of normal seedlings, the average length and the dry mass of the P. vulgaris root as the concentration of P. guajava extracts increased. A higher synchronization index and higher levels of lipid peroxidation were also observed in the presence of the extracts. Therefore, under laboratory conditions, the aqueous extract of dry leaves of P. guajava showed an inhibitory effect on the parameters evaluated.