This study was performed at Rice and Winter Cereal Crops Department of NICS during 2007 and 2008 to investigate the characteristics of rice leaf emergence and to obtain basic data which can be used for rice growth simulation model by which we can forecast rice growth stage and heading date accurately under different cultivars, transplanting date, and climatic conditions. To confirm leaf emergence rate according to rice maturing ecotype, we surveyed the leaf emergence rate and heading date of Unkwangbyeo, Hwayoungbyeo and Nampyeongbyeo which are early maturing, medium maturing and medium-late maturing cultivars, respectively, according to seedling raising duration and transplanting time. When seedling duration was 15 days, the growth duration between transplanting time and completion of flag leaf emergence on main culm were 51.5~78.3 days in Unkwangbyeo, 55.3~87.9 days in Hwayoungbyeo and 58.4~98.4 days in Nampyeongbyeo, respectively. When seedling duration was 30 days, they were 50.1~75.5 days in Unkwangbyeo, 52.4~84.7 days in Hwayoungbyeo and 56.4~93.8 days in Nampyeongbyeo, respectively. As transplanting time delayed, the emerged leaf number after transplanting decreased in all rice cultivars. The cumulative temperature between transplanting time to completion of flag leaf elongation on main culm were 1,281~circC~1,650~circC in Unkwangbyeo, 1,344~circC~1,891~circC in Hwayoungbyeo and 1,454~circC~2,173~circC in Nampyeongbyeo, respectively. Leaf emergence rate on main culm were precisely represented by equation, y = y0 + a / [1 + exp( - (x - x0 ) / b)]c, when we used daily mean temperature as variable.

This study was carried out to develop rice growth model when cultivate early maturing rice cultivar, Unkwangbyeo, in Honam plain area. To confirm leaf emergence rate and variation of heading date, we transplanted 15 day and 30 day old seedling on May 1, May 15, May 31, June 15, June 30, respectively. The growth duration between transplanting and completion of leaf emergence on main culm were 50.1~78.3 days in 2007 and 47.5~74.7 days in 2008. Growth duration diminished gradually as transplanting time delayed, but the difference of growth duration by transplanting time were more bigger than that of seedling day. The emerged leaf number after transplanting on main culm were 8.9~10.9 in 2007 and 8.4~10.9, respectively. The emerged leaf number diminished as transplanting time delayed, but the difference of emerged leaf number by transplanting time were more bigger than that of seedling day. The cumulative temperature between transplanting and completion of leaf emergence on main culm were 1,281~1,650℃ in 2007 and 1216~1560℃ in 2008. The solar radiation between transplanting time and completion of leaf emergence on main culm were 709~1,245MJ/㎡ in 2007 and 722~1,220 MJ/㎡ in 2008. The sunshine hours between transplanting time and completion of leaf emergence on main culm 234~433 hours and 238~431 hours, respectively.