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In order to identifying of high yielding compatible sunflower hybrids for different regions of Iran, a set of 10 exotic hybrids from Serbia, Turkey, and Italy and four Iranian hybrids were evaluated for agronomic traits; days to flowering and maturity, plant height, head and stem diameter, 1000-achenes weight, achene number per head, oil content and achene, and oil yield. The experiments were conducted as completely randomized block design with four replications in Alborz, Mazandaran, Khuzestan, and West Azerbaijan Provinces for two years (2017–2018). According to the results growing period of the hybrids were variable from 86 days for Dukat to 98 days for Fantaziya. The hybrids Slatki and Dukat had the highest (70 g) and lowest (56 g) 1000-achenes weight. The highest oil content was observed in 08TR003 (45.6%). Among the locations, Miandoab had the highest achene yield (3110 kg/ha). In Sari; the hybrids Barzegar, Fantaziya, and Slatki (3080, 2893, and 2853 kg/ha respectively), In Dezful; Barzegar, Cartago, and Oscar (3234, 3409, and 3226 kg/ha respectively), in Karaj; Oscar, Shams, and Fantaziya (3138, 3081, and 3050 kg/ha respectively), and in Miandob Shams, Fantaziya, and Slatki (4093, 4038, and 3895 kg/ha respectively) had the highest achene yield. Considering overall mean Fantaziya, Shams, and Oskar had the highest achene yield (3286, 3145, and 3087 kg/ha respectively), as well as Fantaziya followed by Barzegar and Shams had the highest oil yield (1396, 1335, and 1330 kg/ha respectively). Considering phenotypic variability among the exotic hybrids Fantaziya, Oskar, Slatki, Novak, 08TR003, and Meteor with lower coefficient of variation and higher achene yield considered as the stable higher yielding hybrids in four test locations of Iran. Through identifying high-yielding and compatible hybrids, the results of this study can assists in increasing of sunflower yield and production in Iran.

To evaluate the responses of canola seedlings to different levels of drought stress and nitrogen at different growth stages, a factorial experiment was conducted in a completely randomized design with three replications at the experimental greenhouse of Mohaghegh Ardabili University in 2013. Treatments included three levels of drought stress (30%, 50%, and 70% of FC) and five levels of nitrogen (control, based on soil test results; 25% less than the recommended level; 50% less than the recommended level; 25% more than the recommended level; and 50% more than the recommended level). The recommended level of nitrogen, based on soil test results, was 0.09 g of nitrogen per kilogram of soil. Results showed that drought stress, nitrogen, and their interaction significantly affected the enzymatic activity of antioxidant catalase (CAT), polyphenol oxidase (PPO), and peroxidase (PO) at various stages of growth. Proline was also affected by drought stress and nitrogen. Maximum CAT activity (794.04 OD mg protein min -1 ) was observed at the 4-6 leaf stage under mild drought stress conditions (50% of FC) and a nitrogen application rate 50% less than the recommended level. Increased rates of nitrogen enhanced the PPO activity at the 4-6 and 6-8 leaf stages. PO had a negative response to increased rates of nitrogen application. The highest rate of increase in proline was at the 8-10 leaf stage: 205% and 207% higher under mild drought stress (50% of FC) and severe drought stress (30% of FC) conditions, respectively, compared to favorable moisture conditions (70% of FC). Increased nitrogen application led to an increase in proline production at all stages of sampling (4-6, 6-8, and 8-10 leaf stages).