Phytotoxic interactions in tree crop associations in agroforestry greatly influence crop production. When trees and crops are grown together, they interact with each other, either through overt or indirect allelopathic interaction, inhibiting or stimulating their growth or yield. The present research aimed to test the phytotoxic influence of Psidium guajava aqueous leaf extracts on seed germination, seedling growth and some biochemical changes of Capsicum frutescens L