Vol. 3, Issue 5 (2018)
Allelopathic effect of Chromolaena odorata aqueous leaf extracts on seed germination and seedling growth of selected crop and pasture species in Tanzania
Author(s): BI Muzzo, AJ Mwilawa, DD Maleko, EJ Mtengeti
Abstract: Chromolaena odorata is an invasive weed species adversely affecting both crop and grazing lands in tropical and subtropical areas. This study was designed to investigate the allelopathic effects of C. odorata aqueous leaf extract on seed germination and seedling growth of some species. The selected crops include sorghum, white maize, brown and mug beans while pasture species was Centrosema pubescens (Centro). C. odorata aqueous leaf extract concentrations of 0, 25, 50, 75 and 100% were prepared. The experiment was set under completely randomized design with three replications. Data on seed germination were daily collected while shoot and root length were measured on 10th day of the experiment. Germination percentage (GP), Germination Index (GI), Rate of germination (RG), Inhibitory percentage (IP), Seedling Vigor Index (SVI), relative elongation ratio of root (RERR) and relative elongation ratio of shoot (RERS) were computed. C. odorata leaf extract has significant effect (p < 0.05) on GP, GI, IP and SVI in all crops and pasture. The GP and GI decreased with increased concentration on selected species. However, the impact was rather low for sorghum, brown beans and Centro. At 100 %, SVI and RERRS for brown beans, mug beans and Centro were 131.35, 36.18, 80.88 and 14.57, 17.87, 75.68 respectively. The SVI, RERR and RERS were highly affected at concentration ≥ 50% while GP, GI and RG were inhibited at 100%. Conclusively, C. odorata leaf extract inhibited seed germination and seedling growth of the experimental crop and pasture species. Further investigation on the allelopathic behaviour under field conditions and inhibitory mechanism involved is suggested.