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The allelopathic effect of Callistemon viminalis's leaf extracts on seed germination and growth of Triticum aestivum and Cicer arietinum, as well as associated weeds (Anagallis arvensis, Poa annua, Lepidium didymium, and Vicia sativa), was studied. Different concentrations (2–10%) of aqueous extracts were used, and physiological parameters were measured. Higher concentrations (6–10%) significantly inhibited the germination and growth of wheat and chickpea. In pot assay, the extract did not affect shoot length, dry plant mass, chlorophyll, carotenoid, proline, protein content, stomatal conductance, photosynthetic and transpiration rate, and antioxidant enzymes in crop and various parameters of soil properties in comparison to the control. Both crops grew significantly at lower concentrations. This study suggests that extract of C. viminalis can inhibit the growth of A. arvensis and V. sativa without affecting germination, photosynthetic and biochemical properties of C. arietinum and T. aestivum, and soil properties, making it a potential candidate for bioherbicide development. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the effects of Murraya koenigii (curry leaf) aqueous extract on the seed germination and growth of two crops and their associated weeds (Anagallis arvensis, Poa annua, Lepidium didymum, and Vicia sativa). Wheat (Triticum aestivum) and Chickpea (Cicer arietinum) seeds were soaked in solutions containing 2, 4, 6, 8, and 10% concentrations of aqueous extracts of M. koenigii leaves, while distilled water was used as a control. Higher concentrations of the extract significantly increased the percentage of germination inhibition and decreased the radicle length and plumule length of both crops compared to the control. It was interesting to find that the pot-based experiment had no influence on the shoot length, plant dry mass, chlorophyll, carotenoid, proline, or protein content, stomatal conductance, or photosynthetic and transpiration rate in either crop. Similarly, in comparison to the control, the activity of antioxidant enzymes (peroxidase (PER), superoxide dismutase (SOD), and catalase (CAT)) had no significant influence. Soil physiochemical parameters and weed shoot growth were also investigated. In a Petri plate experiment, 6, 8, and 10% concentrations inhibited germination of both crops. In comparison, in the pot experiment, the growth of both crops was significant at lower concentrations, and 1% aqueous extract of M. koenigii was reported to be lethal to weeds without affecting the soil physiochemical properties. Based on the results of this study, it can be inferred that the reduced germination rate of the tested species after treatment with the extract could be attributed to damage caused by the extracts to the membrane system of the seed. This study concluded that an aqueous leaf extract of M. koenigii can inhibit the growth of weeds without affecting the germination, growth, photosynthetic, and biochemical properties of C. arietinum and T. aestivum or the physiochemical properties of soil; thus, it may be a potential candidate for the development of new bioherbicides. [ABSTRACT FROM AUTHOR]