Effet des extraits de feuilles de gliricidia sepium (jacq.) walp sur la germination des semences de mil (pennisetum glaucum) et d’espèces adventices du Sénégal

This study was carried out in the Botany and Biodiversity Laboratory in order to evaluate the biocidal effect of Gliricidia sepium leaf extracts on weeds for the improvement of millet production. Chemical pretreatments are performed on weed seeds that are unfit for germination. At the end of these tests, it appears that most weed species do not have problems of true dormancy; they are affected by an integumentary inhibition eliminated by pretreatment with water for 72 hours (Digitaria ciliaris, Eragrostis tremula, Mariscus squarrosus) or with concentrated sulfuric acid (Hibiscus asper, Indigofera astragalina, Indigofera hirsuta, Senna obtusifolia, Sesbania pachycarpa and Spermacoce chaetocephala) at varying lengths. Thus, these weed species (09) are retained for the study of the effect of leaf extracts of G. sepium. Extracts of leaves of G. sepium at different concentrations (2.5%, 5% and 10%) are prepared and tested on nine (09) weed species (Digitaria ciliaris, Eragrostis tremula, Hibiscus asper, Indigofera astragalina, Indigofera hirsuta, Mariscus squarrosus, Senna obtusifolia, Sesbania pachycarpa and Spermacoce chaetocephala) and Millet (Pennisetum glaucum). Treatments with G. sepium leaf extracts inhibit the germination capacity of all weed seeds at all tested concentrations, except for Senna obtusifolia, which has germination rates comparable to those of the control (96.67%). The treatments also delay the germination of the seeds of Eragrostis tremula, Mariscus squarrosus, Senna obtusifolia and Sesbania pachycarpa. The effects of treatments increase with concentration and are more pronounced at 10%. The extract of G. sepium at 10% prevents seed germination of Indigofera hirsuta and Spermacoce chaetocephala (TG = 0%). If the 10% leaf extract prevents seed germination of the weeds studied, it has very little effect on millet with germination rates ranging from 84 to 86.67% and average germination times in the vicinity of the control. (1, 19 days). As a result of these results, it appears that the extract of leaves of G. sepium at 10% could serve as a natural herbicide, effective and adapted to the cultivation of millet.