HERBICIDAL POTENTIAL OF DRYLAND PLANTS ON GROWTH AND TUBER SPROUTINGIN PURPLE NUTSEDGE (Cyperus rotundus)

In the current study the herbicidal potential of different dryland plant species to suppress tuber sprouting and growth in the purple nutsedge (Cyperus rotundus) was investigated. The plant species evaluated were Fagonia indica, Aerva javanica, Calotropis procera, Rhazya stricta and Withania coagulans. In a greenhouse experiment, 5 sprouted and 5 non-sprouted tubers of nutsedge were planted in pots containing 250g field-collected soil. Pots were irrigated regularly with aqueous extracts of test plants at five concentrations (0, 25, 50, 75 and 100%; original extract was concentrated 20 times and was considered as 100% concentrated and further concentrations were made accordingly). Extracts of all test plants significantly inhibited nutsedge tuber sprouting and growth. A significant interaction was observed between sprouting index (SI) and final sprouting percentage. While a non-significant interaction was observed between the timing of sprouting initiation and mean sprouting time (MST). Maximum reductions in SI and final sprouting percentage were recorded with Rhazya stricta extracts. Extracts of Rhazya stricta showed maximum suppressive potential of nutsedge density, root and shoot length, root and shoot fresh and dry weight. Overall, the least effective suppression of purple nutsedge was observed for extracts of Fagonia indica. Calotropis procera extracts resulted in the lowest reductions in nutsedge root length of all test plants but all test plants showed similar effects on timing of sprouting initiation and mean sprouting time. The 100% and 75% concentrations provided complete suppression of nutsedge. For all test plants, the 25% extract concentration was least effective and in some cases results were similar to the water-only control treatment. Our findings suggest that several dryland plant species with strong allelochemical properties have the potential to substantially reduce the deleterious impacts of purple nutsedge in dryland cropping systems and warrant further study.