This study was conducted to examine the appropriate transplanting date of the top-quality rice variety, Unkwangbyeo, in Honam plain area. The results obtained from 2006 to 2007 in Iksan are as follows. The number of panicle per m2 increased as the transplanting date became late and the number of grain per m2 was the highest in the plot of which the transplanting date was June 15. Percent ripened grain increased as the transplanting date became late until June 15, however, it decreased in the plot of which the transplanting date was June 30. Imperfect grain increased as the transplanting date became early due to the occurrence of immature rice and cracked rice. Protein content increased as the transplanting date became late, but didn't show statistical significance. Toyo texture increased as the transplanting date became late. Rice yield and the head rice yield increased as the transplanting date became late until June 15, however, they decreased in the plot of which the transplanting date was June 30. Even though the rice price was high in early transplanting cultivation, gross profit was the highest in June 15 transplanting since the rice yield increased as the transplanting date became late until June 15. Considering the yield, rice quality and profit, the most appropriate transplanting date of Unkwangbyeo in Honam plain area is the middle of June.

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.