Effect of different ratios and levels of nitrogen and phosphorus fertilizers, and top dressing of nitrogen fertilizers on growth and yield of groundnut

A field experiment was carried out during 2011 with fourteen ratios of nitrogen (N) and phosphorus (P2O5) fertilizers with constant potassium level (25 kg K2O ha-1) on groundnut cultivar TAG 24 at MARS, UAS, Dharwad. The dry pod yield increased due to increasing N/P ratios upto 0.78. The treatment receiving N/P fertilizer ratio of 0.57 (basal application of 20 kg N, 60 kg P2O5, 25 kg K2O ha-1 + foliar application of nitrogen @ 7 kg N ha-1 at 45 days after sowing and foliar application of nitrogen @ 7 kg N ha-1 at 60 days after sowing) recorded significantly higher dry pod yield (4361 kg ha-1), number of filled pods plant-1 (24.27), total number of pods plant-1 (29.53), 100 pod weight (135.33 g) and 100 kernel weight (41.16 g). This treatment also recorded significantly higher leaf area plant-1 (17.45 dm2), leaf area index (5.82), leaf area duration (136.54 days) and total dry matter production (39.36 g). The treatment receiving N/P fertilizer ratio of 0.70 (basal application of 18 kg N, 46 kg P2O5, 25 kg K2O ha-1 + foliar application of nitrogen @ 7 kg N ha-1 through urea at 45 days after sowing and foliar application of nitrogen @ 7 kg N ha-1 at 60 days after sowing) recorded higher kernel yield (3365 kg ha-1) and harvest index (0.42) and it was on par with the N/P fertilizer ratio of 0.57 (3340 kg ha-1 and 0.40, respectively).