RATE OF NITROGEN AND SULFUR FERTILIZERS ON YIELD, YIELD COMPONENTS AND SEED QUALITY OF OILSEED RAPE (BRASSICA-NAPUS L)

Two experiments were carried out to investigate the influences of nitrogen and sulphur fertilizers on the morphology, reproductive structures and seed quality of new cultivars of oilseed rape (Brassica napus). Yield and yield component responses were not consistent between years and cultivars. For the crop sown in 1988, application of nitrogen at 240 kg/ha increased total dry matter production and combine seed yield. Seed yield increased mainly due to greater number of pods on the terminal raceme and heavier seed weight whereas number of seeds per pod was not affected. Sulphur fertilizer application did not significantly increase plant dry matter production, number of seeds per pod oi individual seed weight. Considerable variation occurred between cultivars and years in seed glucosinolate concentrations with the application of nitrogen and sulphur fertilizers. Nitrogen top dressings caused significant increases in seed glucosinolate concentration in the droughty year of 1989 but not in 1990. Similar significant increases also occurred with sulphur application in 1990. Seed protein content generally increased with increasing rate of nitrogen application, with concomitant decrease in oil content. Sulphur application did not influence oil and protein contents.