[en] The allelopathic effect of pistachios was analyzed by field and laboratory tests. The parameters analyzed in the field trials were the biomass, weed density, weed diversity, and specific richness of the weed community. The studies were carried out in the area under the canopy and in the area beyond the influence of the pistachio tree, and the results obtained were compared. In the laboratory, germination bioassays were carried out on seeds of 11 weed species in root water extract, rhizosphere soil, and leaf water extract. The germination percentage, radicle elongation, epicotyl elongation, and germination index were determined. The results obtained show that significantly less biomass was present in the area under the influence of the trees, and fewer different weed species were detected in that area. In addition, germination bioassays showed that the aqueous leaf extract was a potent inhibitor of germination. The total content of flavonoids and phenols according to the organs (roots or leaves) was also studied. Extracts obtained from leaves showed higher concentrations of total phenols and also of flavones and flavanols than roots. Gallic acid, catechin, myricetin, and quercetin were identified in extracts obtained from both leaves and roots, while naringenin and rutin were identified only in the leaf extract. The presence of phenolic compounds in which allelopathic activity has been previously described and the results obtained in the trials seem to indicate that there is an allelopathic effect of the leaf extract, which could be used for weed control, thus facilitating ecological and/or sustainable management.

[es] El efecto alelop?tico de los pistachos se analiz? mediante ensayos de campo y de laboratorio. Los par?metros analizados en los ensayos de campo fueron la biomasa, la densidad de malezas, la diversidad de malezas y la riqueza espec?fica de la comunidad de malezas. Los estudios se llevaron a cabo en el ?rea bajo el dosel y en el ?rea fuera de la influencia del ?rbol de pistacho, y se compararon los resultados obtenidos. En el laboratorio, se realizaron bioensayos de germinaci?n en semillas de 11 especies de malezas en extracto acuoso de ra?z, suelo de rizosfera y extracto acuoso de hoja. Se determinaron el porcentaje de germinaci?n, el alargamiento de la rad?cula, el alargamiento del epic?tilo y el ?ndice de germinaci?n. Los resultados obtenidos muestran que estaba presente significativamente menos biomasa en el ?rea bajo la influencia de los ?rboles, y se detectaron menos especies de malezas diferentes en esa ?rea. Adem?s, los bioensayos de germinaci?n mostraron que el extracto acuoso de hoja era un potente inhibidor de la germinaci?n. Tambi?n se estudi? el contenido total de flavonoides y fenoles seg?n los ?rganos (ra?ces u hojas). Los extractos obtenidos de hojas mostraron mayores concentraciones de fenoles totales y tambi?n de flavonas y flavonoles que las ra?ces. Se identificaron ?cido g?lico, catequina, miricetina y quercetina en extractos obtenidos tanto de hojas como de ra?ces, mientras que naringenina y rutina se identificaron solo en el extracto de hojas. La presencia de compuestos fen?licos en los que se ha descrito previamente actividad alelop?tica y los resultados obtenidos en los ensayos parecen indicar que existe un efecto alelop?tico del extracto de hojas, que podr?a ser utilizado para el control de malezas, facilitando as? el manejo ecol?gico y/o sustentable.