THE EFFECT OF DIFFERENT NITROGEN DOSES ON SEED YIELD, OIL, PROTEIN AND NUTRIENT CONTENTS OF SPRING RAPE

Abstract In this two seasons experiment, it was aimed to investigate the effects of different nitrogen levels applied to the soil on seed yield, oil, protein content and nutrient uptake of oilseed rape grown under field conditions. Three cultivars of spring oilseed rape (Brassica napus) viz., Lirawell, Semu 86/225 Na and Westar were used. The nitrogen doses applied to the soil were 0, 60, 120 and 180 kg N/ha as ammonium sulfate. Nitrogen doses increased seed yield compared to untreated plants in all three cultivars. The highest seed yield was obtained from the plants which received nitrogen 180 kg N/ha for all three cultivars. The highest seed yield was in cultivar Semu 86/225 Na with 180 kg N/ha and the lowest one was in the Lirawell without nitrogen application. The protein contents in all three cultivars were increased with the highest nitrogen doses compared to untreated plants. However other nitrogen doses did not change protein content consistently. The changes in oil content were also not consistent among nitrogen doses and cultivars. Different nitrogen applications resulted in changes in nutrient levels in leaves of all the three cultivars