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Abstract
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Abstract: Rosa damascena is one of the oldest valuable rose flower varieties that is almost drough tolerant. However, selecting and identifying landraces that are more tolerant to drought conditions will be effective in developing the cultivation of the plant under stress. The most important step in developing drought-tolerant plants is the evaluation and identification of resistant and susceptible genotypes. In this case, an experiment was performed under in vitro conditions using five levels (0, 25, 50, 75, and 100 g/L) of polyethylene glycol (PEG) on four landraces of the Damask rose (Maragheh, Urmia, Pakdasht, and Kashan). Based on the findings, the resistance of the different landraces to a water deficit was measured by the Design-Expert software using the response level (RSM) method. The results showed that Maragheh, with the highest fresh and dry weight, total chlorophyll, chlorophyll a, chlorophyll b, proline and an increase in the superoxide dismutase activity, had a high tolerance to drought stress. Moreover, Maragheh with a decreasing leaf number, height, malondialdehyde, hydrogen peroxide and having a higher membrane stability index, showed a better defence mechanism against oxidative stress than the other landraces. Also, after Maragheh, Pakdasht had the best performance compared to the other two landraces up to 75g/L of PEG, but not as well as Maragheh at the highest level of the tested PEG. Urmia and especially Kashan probably do not have much tolerance to drought stress regarding all the results and levels of desirability.
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