Allelopathic Effects of Aqueous Extract of Thyme (Thymus vulgaris L.) on the Growth and Some Morphological and Physiological Characteristics of Barley (Hordeum vulgare L.)
DOI:
https://doi.org/10.65405/fth3sr08Keywords:
Thyme (Thymus vulgaris L.) plant extract, barley (Hordeum vulgare L.), plant extracts, leaf area, chlorophyllAbstract
This study was conducted in the Botany Laboratory, Department of Biology, Faculty of Science, Al-Marqab University, to evaluate the effect of different concentrations of aqueous extract of thyme (Thymus vulgaris L.) on the growth and some morphological and physiological characteristics of barley (Hordeum vulgare L.). Four concentrations were used in the treatments: control, 10%, 15%, and 20%. The results showed that the 10% concentration produced the best growth response, recording the highest shoot length (18.7 cm) and the highest root length (15.5 cm). Leaf area also increased to 8.12 cm² compared to the control treatment. This concentration also led to an increase in the fresh weight of the root system (0.91 g), while the fresh weight of the shoot system decreased compared to the control. Conversely, increasing the extract concentration to 15% and 20% led to a gradual decrease in most growth indicators, particularly shoot and root length and leaf area, indicating an inhibitory effect at higher concentrations, attributed to the increased concentration of phenolic or allelopathic compounds. The results also showed an increase in chlorophyll a, chlorophyll b, and total chlorophyll content in all extract treatments compared to the control. The 10% concentration recorded the highest values for both chlorophyll a (4.17 µg/ml) and total chlorophyll (6.88 µg/ml), while the 20% concentration recorded the highest value for chlorophyll b (3.25 µg/ml). The study concludes that a 10% aqueous thyme extract is the optimal concentration for improving barley plant growth and increasing photosynthetic efficiency, while higher concentrations negatively affect most growth indicators.
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