Herbicidal effects of Withania somnifera L. leaf extract on Cannabis sativa L., Hordeum vulgare L. and Cicer arietinum

Abstract

We identified the phytochemicals in Withania somnifera L, a multipurpose medicinal plant of the Himalayan región using TLC, FTIR and HPLC. Eleven formulations were made by mixing in different ratios of Withania leaf extract, wood ash and distilled wáter. Wood chips and twigs of 3-years old Pinus roxburghii tree were completely burnt till ashes was used as Wood ash. The 11-formulationss were i.e. formulation I (Withania leaf extract 100%)), formulation II (75:25 concentration (Withania leaf extract: Distilled water)), formulation III (50:50 concentration (Withania leaf extract: Distilled water), formulation IV (25:75 concentration (Withania leaf extract: Distilled water)), formulation V (75:25 concentration (Withania leaf extract: Wood ash)), formulation VI (50:50 concentration (Withania leaf extract: Wood ash)), formulation VII (25:75concentration (Withania leaf extract: Wood ash)), formulation VIII (Wood ash 100%)), formulation IX (75:25 concentration (Wood ash: Distilled water)), formulation X (50:50 concentration (Wood ash:Distilled water)), formulation XI (25:75concentration (Wood ash: Distilled water)). The herbicidal activity of formulations was earlier studied against Cannabis sativa L. (banned narcotic plant). Their herbicidal activity was tested on seeds germination and seedlings growth of Cannabis sativa L weed and 2 crops: Hordeum vulgare L and Cicer arietinum L. In Pot culture, the formulation V spray caused maximum reduction in root length of Cannabis (53 %) > Hordeum (23 %) and Cicer (22 %) than control. The formulations were also tested on crops for their herbicidal effects. In Petri plate bioassy, the formulation V (75:25 concentration (Withania leaf extract: Wood ash) showed maximum reduction in seed germination and seedling growth of C. sativa weed, but had little effect on growth of test crops. The reduction in stem length was maximum (55 %) in Cannabis > Hordeum (20 %) > Cicer (19 %) than control. Glyphosate decreased the stem length of Cicer (80 %) > Hordeum (58 %) and Cannabis (16 %) over control. While the reduction in root length was in Cicer (75 %) > Hordeum (73 %) > Cannabis (18 %) than control. The root and stem extract formulations were more phytotoxic to Cannabis sativa. Formulation V (75:25 concentrations (Withania leaf extract: wood ash)) reduced the number of leaves, number of shoot, root branches and stem and root length of Cannabis sativa.