Nutrient uptake, nutrient availability and quality parameters of mechanically transplanted rice (Oryza sativa L.) under split doses of nitrogen

The field investigation was carried out during kharif 2011 and 2012 at Punjab Agricultural University Ludhiana to see the performance of mechanically transplanted rice (Oryza sativa L.) under split dose of nitrogen.The treatments included 100 kg N ha-1 (N100 ), 125 kg N ha-1 (N125) and 150 kg N ha-1 (N150) in 2 splits before last puddling (BLP) and 15 days after transplanting (DAT), 3 splits (BLP, 15 and 30 DAT) and 4 splits (BLP, 15, 30 and 45 DAT) along with recommended N (125 kg ha-1) in 3 equal splits (BLP, 21 and 42 DAT) and control treatment of 0 kg N ha-1. The grain yield, nutrients (N, P, K) uptake and quality parameters of rice were observed higher with N150 in 4 splits i.e. before last puddling, 15, 30 and 45 DAT as compared to other treatments in both the years.This treatment also resulted in maximum availability of nutrients N and K in soil , which were significantly higher than other treatments during both the years. But available P was observed maximum with N150 in 4 splits, which was at par with N150 in 3 splits during 2011 but in 2012, it was at parwith N150 in 3 splits,N125 and N100 in 4 splits.N150 in 4 splits gave significantly higher brown rice recovery, milled rice recovery and head rice recovery than other treatments. These parameters increased with increase in levels of nitrogen and its split application from zero to 150 kg ha-1. However, there was non-significant effect of different levels of nitrogen and split applications on minimum cooking time, elongation ratio and cooking coefficient of grains. Water absorption ratio by grains from N150 in 4 splits was similar to N150 in 2-3 splits and N125 in 3 splits, but was higher than other treatments. The maximum protein content (5.72-5.75%) was also recorded in N150 in 4 splits. The protein content in grains increased with the split application of different nitrogen levels from 100 to 150 kg N ha-1.