| چکیده انگلیسی مقاله |
Extended abstract Introduction: Chemical compounds in plants include primary or secondary compounds. The allelopathic compounds are mainly of the secondary type, which are released by ways such as leaching, decomposition of plant residues, volatilization, and root exudation. Plants with allelopathic properties have a negative or even positive effect on the germination and growth of other plants by releasing substances in their surroundings. These effects depend on the type of organ, concentration, plant growth location, physiological maturity, etc. Materials and Methods: An experiment was conducted to evaluate the allelopathic potential of wild barley (Hordeum spontaneum) weed on some germination, morphophysiological, and biochemical characteristics of a reference plant sensitive to allelochemicals, cress (Lepidium sativum), in 2021. This experiment was conducted in the form of a completely randomized design with three replications. The treatments included different concentrations of H. spontaneum aqueous extract at 11 levels (0, 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100%). Results: The results showed that different concentrations of H. spontaneum aqueous extract had a significant decreasing effect on the percentage and rate of seed germination, radicle and shoot length, seedling length vigor index, radicle and shoot dry weight, as well as photosynthetic pigments (i.e., chlorophyll a, b, total, and carotenoids) of cress. Their effectiveness was dependent on the concentration threshold of the aqueous extract. In contrast, the content of proline amino acid , soluble sugars, ion leakage, catalase activity, guaiacol peroxidase enzymes, the concentration of malondialdehyde, and phenolic compounds showed an increasing trend compared with the control. In most cases, the highest increase in these compounds was obtained at the 100% aqueous extract concentration of H. spontaneum. This indicates the oxidative stress and high cytotoxicity caused by harmful compounds present in the aqueous extract of H. spontaneum. Conclusions: According to the results of this experiment, it can be decucted that the aqueous extract of H. spontaneum, due to its allelopathic properties, prevented germination and seedling growth of L. sativum. Therefore, according to the proof of the harmful effect of H. spontaneum and its high biomass, it may be possible to introduce the bioactive compounds present in this plant for the production of environmentally friendly herbicides or even the potential to produce new formulations of synthetic herbicides in case its positive effect on other species is proven. Highlights: - The difference in the effect of different concentrations of Hordeum spontaneum weed aqueous extract on germination and seedling growth of a reference plant sensitive to the allelochemicals, Lepidium sativum, is related to their concentration threshold.
- The significant decrease in germination characteristics and photosynthetic pigments of L. sativum indicates the intensity of oxidative stress caused by the harmful compounds in the aqueous extract of H. spontaneum.
- The allelopathic characteristics of H. spontaneum weed can be a suitable candidate for the production of biological herbicides.
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