Effect of drought Stress on Vegetative Growth, Micromorphological and Flower development of Ahmadi and karaj2 Rapeseed Cultivars (Brassica napus L.)

In order to investigate the response of rapeseed to dehydration stress, a split plot experiment was conducted in the form of a complete randomized design with three replications in Karaj at the Seed and Plant Improvement Research Institute. Irrigation was done at two levels of normal irrigation and interruption of irrigation from flowering stage in main plots and plants of Ahmadi cultivar and Karaj2 cultivars in sub-plots. Plants of Karaj 2 cultivar had the highest ratio of cortex to vascular bundle (0.79) and Ahmadi had the highest phloem content (13.3 μm) in roots. In comparison, Ahmadi cultivars had the highest cortex thickness (146.5 μm) and the largest xylem (144 μm), protoxylem (13.3 μm) and parenchyma pit cell diameter (118.16 μm) in the stem. In normal irrigation, Ahmadi cultivars had the highest style length (1.48 mm) and anther filament length (6.32 mm). Ahmadi cultivars were more tolerant of stress due to having the lowest ratio of cortex to vascular bundle and the highest amount of phloem in the roots and having the greatest thickness of cortex in the stem and were identified as resistant cultivars.