Effect of Winter Planting Date on Qualitative Traits and Yield of Spring Rapeseed (Brassica napus) Cultivars by Using Zinc Spray in Karaj Region

To study the effect of winter planting and zinc spraying on yield and yield components of canola (Brassica napus) cultivars, a factorial split plot experiment based on randomized complete block design with three replications was conducted for two years (2014-2015 and 2015-2016 cropping seasons) at the experimental farm of Seed and Plant Improvement Institute of Agricultural Research, Education and Extension Organization of Karaj, Iran.. In this experiment, winter plantings with three levels (24th February, 6th, and 16th March) and Zinc factors with two levels, including application of zinc sulfate spray and spray with pure water assigned to main plots and spring cultivars, including RGS003, Zafar, Julius, Jerry, Zabol 10, Hyola 4815 to subplots. The results of combined analyses of data showed that the effect of year, planting date, zinc spray, cultivar and planting date × cultivar interaction effects on qualitative traits (grain glycosinolate content and fatty acid percentages) in different planting dates and cultivars were significant at 1% level of probabilities. According to the results, the highest (66.89%) and lowest (66.02%) oleic acid percentages belonged to zafar and zabol10 cultivars, respectively. Planting dates × cultivar interaction effect on the glucosinolate content indicated that the lowest glucosinolate content produced by Zafar (8.313 mg.g-1) and hyola4815 (8.567 mg.g-1), when they were sown on March 16th. The results of this experiment showed that delayed planting, decreased percentages of palmitic, linoleic and oleic acids of seed oil, while increased percentages of linolenic and erousic acids and glycosinolate contents.