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There are different climate classes in Iran where about 85% of the agricultural lands are located in arid and semi-arid regions. To mitigate or compensate effects of drought stress and increase crop fitting and yield, effects of micronutrient application have been studied by several researchers. Field experiments were conducted during the 2021–2022 and 2022–2023 crop seasons to investigate the effect of micronutrients on quantitative and qualitative characteristics of canola cultivars under late-season drought stress conditions. The experiments were arranged in a factorial split-plot design, with two irrigation treatments – normal irrigation (control) or restricted irrigation at flowering stage – and four foliar applications of Zn and Mn after rosette stage (F1: Water, F2: ZnSO4, F3: MnSO4 and F4: ZnSO4 + MnSO4) as the main factor. Winter canola cultivars, including Okapy, Hyola401 and Hyola308, as sub-factor. The results showed that limited irrigation at flowering reduced seed yield, oil percentage and fatty acids content in different canola cultivars. Most of the canola oil is composed of unsaturated fatty acids, and the occurrence of drought stress at the reproductive stage reduced oil quality. By contrast, the minimum yield loss was obtained from Hylon401 cultivar, an early mature cultivar. Overall, it is recommended Hylon401 cultivar for normal irrigation and Hylon308 cultivar for a drought environment when considered the acceptable seed yield in canola. In general, it is suggested that a suitable performance of canola seeds is achieved by foliar application of manganese and zinc. [ABSTRACT FROM AUTHOR]

An experiment was conducted to study the effects of solar UV radiation, UV-B, UV-C radiation, and elevating CO2 on some physiological attributes of two canola cultivars (Brassica napus L.) under complete irrigation or limited irrigation in two continuous years. Generally, elevated CO2 increased leaf-soluble carbohydrates, reducing sugars, glucosinolate, and Fv/Fm ratio while carotenoids and soluble protein were decreased due to elevated CO2. In addition, UV radiation decreased leaf-soluble carbohydrates, reducing sugars, chlorophyll, proline, and Fv/Fm ratio and increased UV absorbing pigments, soluble proteins, and glucosinolate. [ABSTRACT FROM AUTHOR]

In this study, we studied the combined effects of UV radiation, CO2 and water stress on the morphological traits, yield and yield components of canola (Brassica napus cv. 'Okapi' and 'Talaye') under twelve growth conditions: complete irrigation with ambient CO2 with UV-A (control), complete irrigation with ambient CO2 with UV-B, complete irrigation with ambient CO2 with UV-C, limited irrigation with ambient CO2 with UV-A, limited irrigation with ambient CO2 with UV-B, limited irrigation with ambient CO2 with UV-C, complete irrigation with elevated CO2 with UV-A, complete irrigation with elevated CO2 with UV-B, complete irrigation with elevated CO2 with UV-C, limited irrigation with elevated CO2 with UV-A, limited irrigation with elevated CO2 with UV-B and limited irrigation with elevated CO2 with UV-C. he results showed that water stress significantly decreased all of traits except for the oil percentage. Additionally, an elevated level of CO2 significantly increased the final yield, 1000-seed weight, oil yield, plant height, specific leaf area and number of branches per plant, whereas UV radiation decreased all of the traits in this experiment. Elevated CO2 ameliorated the adverse effects of UV radiation in the final yield, seed weight, oil percentage, oil yield, plant height, specific leaf area and number of branches per plant. his study showed that elevated CO2 can partially ameliorate some of the adverse effects of UV radiation in canola plants. Furthermore, in this study, we observed that the increase in the yield was due to the increase in the seed weight and number of branches caused by elevated CO2 in canola plants. In addition, the maximum yield was obtained from the 'Talaye' cultivar under conditions of sunlight, full irrigation and elevated CO2. [ABSTRACT FROM AUTHOR]