Abstract: A three-year experiment was conducted in order to examine the effects of potassium (K) application rates on plant K accumulation, K use efficiency and grain quality of japonica rice (Wuxiangjing14 and Wuyujing3) from 2000 to 2002 in Dongtai, Jiangsu, China. When K fertilizer was applied as basal dressing, K uptake of rice population amounted to maximum at the K2O application rate of 12.8 kg/667m2 and excessive-fertilization decreased population K uptake, grains K absorption always increased with the increase of K fertilizer application rate, only the increment extent decreased gradually. Potassium uptake by rice population peaked in the growth season from the elongation stage to the heading stage. Non-fertilization and excessive-fertilization enhanced the proportion of plant K uptake before the elongation stage, but reduced effective panicles. With one-time application of K fertilizer as basal dressing, the highest grain yield and quality occurred at the level of 1∶0.8 of N∶K2O ratio, which significantly increased the percentage of earbearing tiller and setting percentage and K physiological and agronomy efficiencies. Also, low chalkiness degree and amylose content were found at this level. Compared to one-time application of K fertilizer as basal dressing, fertilization as panicle fertilizer caused increases in plant K uptake and proportion from elongation stage to heading stage, the number of filled grain, the setting percentage and gel consistency. Moreover, K fertilization as panicle fertilizer significantly decreased chalkiness degree and amylose content, resulting in considerable high grain yield and quality.

Key words: High grade rice, K application rate, Plant K uptake, Rice quality