PHYTOTOXICITY OF Lantana camara L. EXTRACTS AND SOIL FROM BENEATH ITS CANOPY ON CABBAGE (Brassica carinata A.)

Abstract

Lantana camara is an invasive weed species that has allelopathic effects on crops and other indigenous associated plants. Allelochemicals from such plants may also have positive or negative impact on soils. Therefore, the research was carried out to investigate the allelopathic effect of leaf extracts of Lantana camara and soils invaded by it on Brassica carinata. Leaf extracts of Lantana camara were prepared with water, hexane and methanol, while distilled water alone was used as control to evaluate germination parameters and growth of seedlings of Brassica carinata under laboratory condition. Soil seed-bed and extracts were also prepared from soils sampled from different sites of distance gradient from Lantana camara to evaluate germination parameters and growth parameters of Brassica carinata. Similarly, soils sampled from different sites in distance gradient from Lantana camara were also used to grow Brassica carinata in greenhouse. Results showed that water extracts negatively affected germination and growth parameters under laboratory conditions (p<0.05). Comparison between three solvents extracts impact showed that water extract was superior to hexane and methanol extract in negatively affecting performance of the test plant. However, seed germination percent was significantly reduced by soil extracts sampled from two meters away from lantana thicket (p>0.05). Soil pH was found to decrease with increasing distance from beneath lantana canopy. Available phosphorus and total nitrogen were relatively higher in soils collected from 1 and 2 m away from lantana canopy. In greenhouse experiment significant difference was observed between soils of different distance gradient from Lantana camara in seed yield of B. carinata. Overall, results of this study showed that Brassica carinata is sensitive to allelochemicals from Lantana camara and it is not advisable to cultivate in areas with huge decomposition of Lantana camara.