English

Abstract

Couroupita guianensis Aubl. has been traditionally used for medicinal as well as ornamental purposes, but the allelopathic potential of this species has not yet been reported. Hence, the aim of this study is to explore the allelopathic activity of C. guianensis leaves. We examined the effect of aqueous methanol extracts of the leaves of this species at five different concentrations (1, 3, 10, 30, and 100 mg dry weight (DW) equivalent extract mL) on the germination of lettuce (Lactuca sativa L.) and barnyard grass (Echinochloa crus-galli (L.) Beauv.), and on the growth of cress (Lepidium sativum L.), lettuce, alfalfa (Medicago sativa L.), barnyard grass, timothy (Phleum pretense L.), and Italian ryegrass (Lolium multiflorum Lam.) seedlings. The germination of lettuce and barnyard grass, as well as the growth of all test plants, was inhibited by leaf extracts of C. guianensis at concentrations ≥ 1 mg DW equivalent extract mL. The extract obtained from 100 mg C. guianensis leaves completely inhibited germination of lettuce or significantly delayed germination of barnyard grass. The hypocotyl/coleoptile and root growth of all test plants were inhibited by the leaf extracts to less than 10% of control hypocotyl/coleoptile and root growth at the concentration of 100 mg DW equivalent extract mL, except for the hypocotyl/coleoptile growth of alfalfa and barnyard grass. The ranges of I50 values of hypocotyl/coleoptile and root growth of all test plants were 1.22–10.24 and 0.76–3.97 mg DW equivalent extract mL, respectively. The inhibitory activities increased with increasing extract concentrations. The present results suggest that C. guianensis may have allelopathic potential and thus possesses allelopathic substances. Therefore, the leaves of this species could potentially be used as mulch and/or soil additive to control weeds in sustainable crop production.