Effect of Aqueous Extract of Grass Weeds on Seed Germination and Seedling Growth of Vegetable Crops

Abstract

Aim: Toxicity of grass weeds on crop growth through root exudates occurs naturally but no such study was conducted on the seed germination and seedling growth of some important vegetables of Bangladesh. Therefore, the aim of the research was to evaluate the effects of some grass weed extracts like crabgrass  (Eleusine indica), nutgrass (Cyperus rotundus) and bermudagrass (Cynodon dactylon) on the germination and seedling growth of some vegetable crops like okra (Abelmoschus esculentus), radish (Raphanus sativus), water spinach (Ipomoea aquatica) and red amaranth (Amaranthus gangeticus). Study Design: The experiment was laid out in a Completely Randomized Design (CRD) where each treatment was replicated five times. Place and Duration of Study: The experiment was conducted in the Plant Ecology Laboratory, Department of Crop Botany, Bangladesh Agricultural University, Mymensingh during July 2015 to November 2015. Methodology: Paste of 100 g of each of grass weed was prepared with distilled water taking in mortar and pestle. Final volume was made 100 mL which was treated as absolute extract (100%). Five levels of test solutions were prepared from each absolute weed extract. The test solutions were (i) control (distilled water), (ii) absolute weed extract 100% from each weed and its dilution (iii) 50%, (iv) 25%, and (v) 12.5% with distilled water. Ten mL test solution was used to moisten the tissue papers placing them in each petri dish. Theses treated petri dishes were used for the germination and seedling growth of the vegetable seeds at ambient conditions. Results: Germination percentage in all the vegetable crops was significantly inhibited by the grass weed extracts in a concentration dependent manner. The germination of the seed and seedling growth were decreased with increase in concentration of the extracts and the highest inhibitory effects were observed in 100% concentration. Among the extracts of three different grass weeds, nutgrass showed more toxic effect on the seed germination and seedling growth of test crops than other weeds. Radish seedling was more susceptible than other vegetable crops to the said weed extracts. Conclusion: The aqueous extracts from grass weeds had inhibitory effect on both germination and seedling growth of vegetable crops.