Characteristics of Uptake of Nitrogen, Phosphorus, and Potassium and Partitioning in Mechanical Transplanting Japonica Rice: Characteristics of Uptake of Nitrogen, Phosphorus, and Potassium and Partitioning in Mechanical Transplanting Japonica Rice

From 2008 to 2009, two more than 6.7 ha high-yield demonstration fields at Caoqiao (using cv. Wuxiangjing 9) and Qianhuang (using cv. Wuyunjing 7) in Wujin County, Jiangsu province, were used to investigate the nutrient uptake and parti-tionging characteristics of mechanical transplanting rice. The results showed that 80% of grain yield of mechanical transplanting rice came from the dry matter accumulation after heading, dry weight decreased in leaves while increased in stem sheath after heading. Leaves were also the main contributor of nitrogen translocation. Nitrogen uptake of mechanical transplanting rice in-creased with the yield, and the increased nitrogen uptake mainly originated from the nitrogen accumulation after heading. With the increasing yield, the accumulation and proportion of nitrogen from heading to maturity increased. At the same time, the uptake of P2O5 and K2O increased while the dry weight accumulation ratio reduced. The nitrogen harvest index was between 0.51 and 0.61, the P2O5 harvest index was about 0.75, and the K2O harvest index was close to 0.20. For achieving high yield in mechanical transplanting rice, nitrogen requirement for 100 kg grains should be 2.0–2.1 kg, and the optimum ratio of NPK should be 2.0 : 0.9 : 1.4.