Document Type : Original Article
Authors
1
Department of Plant Production and Genetics, Faculty of Agriculture and Natural Resources,University of Mohaghegh Ardabili, Ardabil, Iran.
2
Department of Plant Production and Genetics, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran
3
Department of Plant Ecophysiology, Faculty of Agriculture, University of Tabriz, Tabriz, Iran
Abstract
َAllelopathic compounds released from plant residues are among the important factors limiting seed germination and seedling establishment in agricultural systems, while their sustainable management remains a major challenge. Meanwhile, evidence regarding the effectiveness of nanobiochar in mitigating allelopathic stress and the physiological mechanisms underlying this response remains limited. Therefore, this study was conducted to evaluate the allelopathic effects of alfalfa extract and to investigate the role of biochar and nanobiochar in mitigating its adverse effects on germination indices and physiological responses of sorghum seedlings. The treatments consisted of five concentrations of alfalfa extract (0, 6.25, 12.5, 25, and 50%) and three biochar treatments (control, biochar, and nanobiochar). The results showed that increasing the concentration of alfalfa extract significantly reduced the germination percentage, germination rate, and seedling dry weight of sorghum, whereas the application of biochar, particularly nanobiochar, improved these parameters and alleviated the inhibitory effects of the alfalfa extract. In addition, increasing concentrations of alfalfa extract simultaneously enhanced the antioxidant and osmotic responses of seedlings, as indicated by increased activities of catalase and polyphenol oxidase and higher contents of proline and total phenolics. The application of biochar, particularly nanobiochar, attenuated these stress-related responses, with the highest germination percentage (98.33%) and seedling dry weight recorded in the nanobiochar treatment in the absence of alfalfa extract. Overall, the findings indicate that nanobiochar effectively alleviates the inhibitory effects of allelopathic compounds in alfalfa extract by improving germination performance and modulating antioxidant defense responses. Therefore, nanobiochar may serve as a practical strategy for managing allelopathic plant residues and promoting seedling establishment in sustainable agricultural systems.
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