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Abstract
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Drought stress is one of the major abiotic stresses that impair the growth and production of canola plants in arid and semi-arid
zones, which necessitates the development of drought-resilient cultivars. The study aimed at determining the morphological,
biochemical, and physiological responses of six different canola cultivars under three drought stresses imposed by polyethylene
glycol. The main and interaction effects of cultivar and drought stress were determined using analysis of variance. The
results showed a considerable decline in root length due to drought stress regardless of the cultivar. A significant interaction
between cultivar and stress was detected on dry weight, height, and leaf area traits. Accordingly, growth parameters were
observed to be linked with drought tolerance, and Hyola308 and Sarigol were identified as the most drought tolerant and
sensitive cultivars, respectively. The values of chlorophyll contents in Hyola308 cultivar were remarkably higher than those
in Sarigol under moderate-drought stress, while Sarigol maintained higher chlorophyll contents under severe stress. Increasing
drought stress enhanced proline content and antioxidant enzyme activities (catalase and peroxidase) regardless of the
cultivar. But a significant decrease in total soluble sugar was observed as drought intensity increased. This reduction in total
soluble sugar content was about 38% lower in Hyola308 than in Sarigol. Therefore, some canola cultivars might mitigate
drought stress effects by enhancing their proline and antioxidant system during drought stress. Furthermore, maintaining
higher soluble sugar levels and greenness stability in response to increased drought stress might be a part of Hyola308’s
cultivar stress management strategy.
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