Macro-element absorption at maturity in relation to grain yield in high-yielding rice cultivars

Abstract

By applying nitrogen (N) and phosphorus (P) fertilizers at different rates and times to high-yielding rice cultivars, we determined the absorption of N, P, and potassium (K) in relation to the grain yield. The results showed that, at a higher top-dressing rate of N, the grain yield increased and the absorption of N, P, and K was stimulated, whereas top-dressing of P did not significantly increase the grain yield and nutrient absorption. The absorption of N, P, and K differed markedly among the cultivars, even at the same level of grain yield in the same field (for Yangdao 4 and Suweon 258). N absorption in line 9004 was 29.2 g m⁻² for a paddy grain yield of 1,250 g m⁻² (brown rice: about 1,000 g m⁻²), being much higher than the value reported in the literature. The ratio of N : P : K absorption at different yield levels revealed that, with the increase of grain yield of the cultivars, the absorption of P and K relative to the absorption of N decreased. The absorption amounts and ratios of N, P, and K depended on the cultivars, yield levels~, and possibly, soils of the field.

Key Words:

• fertilizer application
• high-yielding cultivar
• nutrient absorption
• rice
• yield