Effect of nitrogen and phosphorus levels and ratios on seed yield and nutrient uptake of sunflower hybrid DSH-I

A field experiment was conducted on medium black clayey soils under rainfed conditions at Mam Research Station University of Agricultural Sciences (UAS) Dharwad India during kharif 1999 to study the effect of different levels and ratios of nitrogen and phosphorus on seed yield and nutrient uptake of the sunflower hybrid DSH 1 The experiment consisted of nine treatments ie N/P ratios with two N/P ratios of < 1 0 (0 67 and 0 80) N/P ratio of 10 consisting of two ratios and four N/P ratios of > 1 0 (1 20 1 30 1 60 and 2 00) along with control (no nitrogen and phosphorus) as keeping potassium level (60 kg K2O ha l) as constant The results showed that nitrogen and phosphorus applied in N/P ratios of > 1 0 with 2 00 1 25 1 00 fertilizer level and N/P ratio of 1 0 with 2 00 2 00 1 00 fertilizer level produced 21 and 27 percent higher seed yield over the UAS Dharwad fertilizer recommendation i e N/P ratio of < 1 0 with 1 00 1 25 1 00 fertilizer level (2800 kg ha !) At maturity higher nitrogen (177 72 kg and 186 27 kg N ha l) phosphorus (23 66 kg and 27 75 kg P2O5 ha ') and potassium (124 85 kg and 126 68 kg K2O ha :) uptakes were obtained in the treatment receiving N/P ratio of > 1 0 with 200 125 1 00 (120 kg N 75 P2O5 and 60 kg K2O ha') and in the treatment receiving N/P ratio of 1 0 with 2 00 200 100(120kgN 120 P2O5 and 60 kg K2O ha l) fertilizer levels as compared with the UAS Dharwad fertilizer recommendation i e N/P ratio of < 1 0 with 1 00 1 25 1 00 (60 kg N 75 P2O5 and 60 kg K2O ha ').