Allelopathic Effect of Lotus and Arrowhead Weed on Wheat, Wild Oat and Milkthistle Germination
ABSTRACT: An experiment was conducted to investigate the allelopathic effects of lotus (Nelumbo nucifera Gaertn.) and arrowhead (Sagittaria sagittifolia (Brummitt & Powell): L.) on seed germination of wheat and two associated weeds, namely, wild oat (Avena fatua L.) and milk thistle (Silybum marianum (L.) Gaertn.). The experiment was laid out in a Completely Randomized Design during May, 2014. Dried biomasses of lotus and arrowhead leaves were soaked in distilled water for 48 hrs for extract preparation. The extracts were applied at a rate of 5 and 10% concentrations to the seeds of wheat, wild oat and milk thistle at 25 °C in 10 cm wide Petri plates. A control treatment where only distilled water was applied to the seeds, was included for comparison. Data were recorded on germination (%), shoot length (cm), shoot and root fresh weights (g). The results revealed that 10% lotus extract reduced germination of wild oat (0.00%) and milk thistle (13.3%) but comparatively enhanced that of wheat (20%). By contrast, arrowhead totally inhibited germination of wheat and wild oat as compared to milk thistle (16.66%). Similarly, 10% lotus extract favored shoot length and root weight of wheat and milk thistle, whereas 100% inhibited wild oat. By comparison, arrowhead completely inhibited shoot length and root weight of wheat and wild oat at 10% conc. and enhanced milkthistle (3.00 cm and 3 g). A higher lotus extract conc. affected wild oat more than wheat and milkthistle, while arrowhead weed affected almost all test species. In conclusion, these aquatic weeds can be used as mulch in wheat in nearby fields of the infested aquatic water bodies for wild oat control, weed biomass disposal and nutrient addition to the soil.