Effect of nitrogen sources, sulphur and boron levels on productivity, nutrient uptake and quality of sunflower (Helianthus annuus)

A field experiment was conducted during spring season of 2005 and 2006 on sunflower (Helianthus annuus L.) at New Delhi to study the effect of N sources (prilled urea and calcium ammonium nitrate), S levels (0, 25 and 50 kg/ha) and B levels (0, 0.75 and 1.50 kg/ha) on yield attributes, yield and the oil quality of spring sunflower. Application of N, S and B fertilizers increased significantly yield attributes, yield and the oil quality parameters of spring sunflower. Calcium ammonium nitrate proved superior to urea in terms of nutrient concentration and their uptake by sunflower. Application of 25 kg S/ha was more effective in increasing the growth, yield attributes and yields than of 50 kg S/ha. However, the highest seed yield (1.99 t/ha) was recorded with 50 kg S/ha, which was 13% higher than that of the control. Boron application @ 0.75 kg and 1.5 kg/ha was effective and the crop responded well up to the second dose, and the higher (1.5 kg/ha) level gave the highest seed yield (2.01 t/ha), which was 13.5 and 6.3% more than of the control and 0.75 kg B/ha respectively. It also increased the total nutrient concentration and their uptake by sunflower. Application of S and B markedly improved the content of unsaturated fatty acids (linoleic and oleic) and reduced that of the saturated fatty acids (palmitic and stearic). S and B application reduced the saponification but increased the iodine value significantly. The N sources and S and B levels did not show marked changes in the acid value of sunflower oil. Thus, application of 80 kg N/ha through calcium ammonium nitrate along with 25 kg S/ha and 1.50 kg B/ha would be sufficient to sustain the productivity and quality of spring sunflower under north Indian conditions.