Effect of N, P, K and Plant Density on Grain Yield of Rice Cultivars with Semi-erect Panicles

In order to increase grain yield of rice, a series of field experiments were conducted using cultivars, Shendao 3 and Shendao 9, with semi-erect panicles treated with seeding rate, transplanting density and application levels of nitrogen (N), phosphorus (P), and potassium (K). The results indicated that grain yield of Shendao 3, or Shendao 9, was affected by the treatment factors. For the two cultivars, high yield could be achieved when N, P and K were applied and plant densities were performed with the amounts corresponding to the level codes 1, 0, -2, 0 and 0. Conversely, deficiency or over application of N, P and K, or plant density, could decrease the grain yield. Increasing application level of the fertilizers from very low (code -2) to very high (code 2), agronomic efficiency (AE) of N, or P, decreased substantially.