Allelopathic Effects of Lepidium sativum Aqueous Extract on Germination and Seedling Growth of Phalaris minor: A Dose-Response Study

This investigation analyses the allelopathic effects of aqueous extract of Lepidium sativum (garden cress) against the annual weed Phalaris minor (red rescue grass). This weed is a known problem in wheat crops. The application of Lepidium extracts with different concentrations of 0 to 80 percent was made over P. minor seeds in the laboratory and the growth parameters including the root and shoot length, fresh weights, germination percentage, mean emergence time, germination index and time to 50 percent emergence were analyzed. The lepidium extract was analyzed using HPLC and quercetin, gallic acid, vanillic acid, and p-coumaric acid were identified as the phenolic compounds responsible for allelopathic effects. The conclusion drawn is that there were significant concentration-dependent effects of Lepidium sativum extract on Phalaris minor. Root length was inhibited at 80 percent by 47 percent of the control, whereas shoot length exhibited a potential hormetic response and increased by 25.6 percent at 20 percent. There were variable responses of fresh weights and germination parameters across the extract treatments. A biphasic dose-response model identified an EC50 value of 12.4 percent for root length. The study showed that Lepidium extracts possess significant allelopathic potential against P. minor and can be helpful in sustainable weed management. However, the complex dose-dependent responses, including the hormetic effects, should be considered carefully for practical applications. The study contributes to the research on plant-derived allelochemicals with the potential for eco-friendly weed control while highlighting the importance of dose-response relationships in allelopathic interactions. Further field studies are required to validate the findings under real-world conditions. It also calls for broader ecological studies to recognize the potential adverse implications of artificial allelopathic procedures on the environment.