Head rice yield of “super” hybrid rice Liangyoupeijiu grown under different nitrogen rates

“Super” hybrid rice varieties have been widely grown in farmers’ fields since the late 1990s in China due to their high yield potential. The objective of this study was to compare head rice yield and related grain quality traits between a “super” hybrid variety, Liangyoupeijiu (LYPJ), and an ordinary hybrid variety, Shanyou 63 (SY63), across a wide range of nitrogen (N) rates. The two hybrid varieties were grown under field conditions with seven and six N treatments in 2004 and 2005, respectively, in Hubei province, China. Grain yield, head rice yield, head rice percentage, chalky rice rate and other grain quality traits were measured in the two years. Although the difference in grain yield was small between the two varieties, the average head rice yield across N treatments for LYPJ was 34% and 24% higher than that for SY63 in 2004 and 2005, respectively. Head rice percentage was significantly affected by N rates, but LYPJ maintained higher head rice percentage than SY63 across a wide range of N rates. The higher head rice percentage of LYPJ was associated with its lower chalky rice rate compared with SY63. LYPJ had higher amylose content, greater gel consistency, and lower protein content than SY63, suggesting a better palatability of cooked rice for LYPJ than for SY63.