Seed yield and quality of winter oilseed rape as affected by nitrogen rates, sowing time, and fungicide application

This work reports the results of studies on the impact of sowing times (three dates), application of fungicides (protected and unprotected plots), and nitrogen rates (five treatments) on the seed yield, contents of crude protein (CP), glucosinolates (GSL), and crude fat (CF) in seed and on major unsaturated acids (oleic C18:1, linoleic C18:2, and linolenic C18:3) in oil of winter rape (Brassica napus L.) cv. Kasimir. A split-split plot design was used in the field trial conducted on Endocalcaria-Epihypogleyic Cambisol during 1998-2002. Seed samples were analyzed by near infrared spectroscopy. ANOVA analysis was used to assess the significance of each factor for the yield and quality of seed of the tested cultivar. The seed yield significantly depended on harvest year, N rates annually, sowing time in three experimental years, and fungicide application in two years. CF and CP concentrations were significantly affected by sowing time and N rates each year of the experiment. A significant effect of fungicides was identified only in one harvest year. GSL concentration was significantly affected by sowing time in three years, by fungicides in two years, and by nitrogen rate annually. The effect of the studied factors on the composition of major unsaturated acids was inconsistent. Sowing time significantly affected the content of all three unsaturated acids in two years and fungicides only in one of the four harvest years.