ASSESSMENT OF PHYTOTOXIC ACTIVITY OF SOME SELECTED MEDICINAL PLANTS IN BANGLADESH

Abstract

The study was carried out at the Laboratory of the Department of Agricultural Chemistry of Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka, during the period from December 2019 to March 2020. Investigation was conducted to evaluate the effect of five medicinal plant species (Henna, Gardenia, Bohera, Nagesshor and Tamarind) on phytotoxicity regarding germination and root and shoot growth of two test species (okra and barnyard grass). Five concentrations of each medicinal plant extract viz. P 0 (control; no extract), P 1 (0.01 g dry wt. eq. extract/mL), P 2 (0.03 g dry wt. eq. extract/mL), P 3 (0.1 g dry wt. eq. extract/mL) and P 4 (0.3 g dry wt. eq. extract/mL) were used for phytotoxicity test. The experiment was laid out in Completely Randomized Design (CRD) with three replications. Results showed that all the test species were found sensitive under extracts of all five medicinal plants. Results indicated that all concentrations of plant extract showed phytotoxic effect on okra and barnyard grass. Among all concentration of plant extract, P 4 (0.3 g dry wt. eq. extract/mL) showed highest phytotoxic effect on both okra and barnyard grass seeds. We found that Gardenia extract at P 4 (0.3 g dry wt. eq. extract/mL) concentration in okra seeds showed highest phytotoxic effect for seed germination (30%). Similarly, Henna extract at P 4 (0.3 g dry wt. eq. extract/mL) concentration in barnyard grass seeds showed highest phytotoxic effect for seed germination (30%). Again, in terms of root length of okra seeds, Bohera extract at P 4 (0.3 g dry wt. eq. extract/mL) showed highest phytotoxic effect and gave lowest root length (0.72 mm). Similarly, Bohera extract at P 4 (0.3 g dry wt. eq. extract/mL) concentration on barnyard grass seeds showed highest phytotoxic effect for shoot and root length (0.67 and 0.99 mm, respectively). The above results suggested that those medicinal plants may have phytotoxins and could be use as bioherbicide for successful crop production.