부산대학교 도서관

Meeting the demand for high-quality japonica rice is a major chal enge facing China’s grain security. ln the present study, a two-year field experiment was conducted to investigate the yield, quality, and profitability of japonica rice varieties (including hybrids and inbreds) grown in the late season as compared with local elite indica hybrids in a double rice cropping system of China where indicas are traditional y planted. lndica hybrids had significantly longer vegetative (from sowing to heading) and total (from sowing to maturity) growth durations than japonicas in both 2011 and 2012, while reproductive growth duration (from heading to maturity) was longer for indica hybrids than for japonicas in 2011 but not in 2012. lndica hybrids produced higher grain yield than japonicas in 2011, but with no significant differ-ences in 2012. Japonicas had higher brown rice, mil ed rice, and head rice percent-ages than indicas, but had lower gelatinization temperature and amylose content, while with no significant differences in gel consistency and protein content. lndica hybrids tended to have lower chalky grain percentage and chalkiness degree than japonicas, though the differences were not statistical y significant due to large geno-typic variations. The net returns were 16.1% and 9.9% greater for indica hybrids than for japonica hybrids and japonica inbreds in 2011, with only 3.8% and 1.3% in 2012, respectively. Thus, our results suggest that replacing indicas with japonica va-rieties as late rice may not be feasible at the present site unless local y adapted japonica varieties are developed.