Abstract:

Rice is one of the most important food crops in China. Elucidation of nutrient requirement and absorption has great significance in the realization of high-yielding, good quality and high efficiency in rice. The objective of this study was to investigate the characteristics of nutrient absorption in super-high-yielding cultivation (SHYC, grain yield >11 t ha^-1) and in high-yielding cultivation as the control (grain yield > 7.5 t ha^-1) using two mid-season and late-maturity japonica rice cultivars, Huaidao 68 and Zhendao 88. The absorption and accumulation of nitrogen (N), phosphorus (P) and potassium (K) in the plants were analyzed. The results showed that plants in SHYC absorbed and accumulated less N before the critical stage of productive tillers and more N after the jointing stage, when compared with the those in control. The amount of P absorbed in SHYC was more than that in the control at each growth stage, especially at later growth stages. There was no significant difference in K absorption and accumulation between the SHYC and the control before the critical stage of productive tillers, whereas the plants in SHYC absorbed more K than in the control from jointing to maturity. Input of N balanced the output in SHYC, but the control showed more input than output in N. There were more outputs than inputs in P and K for both SHYC and high-yielding cultivation, especially the former. The amount absorbed of N, P, K for the production of 1 000 kg grains was 21.6–21.9 kg, 6.7–7.2 kg, and 24.8–25.6 kg, respectively in SHYC, and 23.8–24.3 kg, 6.8–7.3 kg, and 27.4–29.0 kg, respectively, in the control. The results indicated that the mid-season japonica rice with SHYC absorbed nutrients less at early growth stages whereas more during the later growth period, and increased the internal nutrient efficiency. The characteristics of nutrient absorption and optimized nutrient management for mid-season japonica rice with SHYC were discussed.

Key words: Rice, Super-high-yielding, Nutrient, Absorption, Management