Document Type : Full Paper
Authors
Department of Horticultural Sciences, Faculty of Agriculture, Lorestan University, Khorram Abad, Iran
Abstract
The pre-treatment of seeds and seedlings is an easy, low-cost, and low-risk method that improves plant growth and enhances their resistance to environmental stresses. The present research was conducted to evaluate the potential of increasing drought resistance in rosemary with pre-treatment of UV radiation, as a split plots in a completely randomized design with three replications. UV radiation treatment was applied at three levels (control, UV A, and UV B) and drought stress at three levels (100±10, 75±10, and 50±10% field capacity). The results showed that leaf length, and shoot and root weight decreased with drought stress. However, internode length, plant height, shoot dry weight, leaf dry weight, leaf width, root dry weight, number of nodes, chlorophyll a, chlorophyll b, total chlorophyll, relative leaf water content, and carotenoid content decreased in the 50% field capacity treatment. Conversely, drought stress led to an increase in malondialdehyde, electrolyte leakage, proline, catalase, peroxidase, ascorbate peroxidase, total phenol, flavonoids, and antioxidant activity. UV B pre-treatment resulted in a significant increase in carotenoids, phenols, flavonoids, proline, and catalase, peroxidase, and ascorbate peroxidase activity. Activation of these stress resistance mechanisms by UV-B led to less increase in malondialdehyde and electrolyte leakage, as well as a smaller decrease in photosynthetic pigments in response to drought stress compared to untreated plants. Therefore, it can be said that pre-treatment with UV-B has resulted in a better physiological response of rosemary to drought stress, but it did not have a specific effect on the growth and yield of the plant.
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