Abstract
In order to avoid a high temperature during the ripening period, the effects of late transplanting and high planting density on the growth, yield and grain quality of rice (Oryza sativa L. cv. ‘Koshihikari’) were investigated for two years. Transplanting in mid-May (late transplanting) reduced maximum tillers number and panicle number than did transplanting on late-April (early transplanting), resulting in yield decrease. However, late transplanting improved grain quality in 2005 when the late transplanting lowered temperature during the ripening period. Under early transplanting, high planting density led to overluxuriant growth and, in some cases, the extreme decrease in leaf color, resulting in the poor grain quality. Under the late transplanting, on the other hand, high planting density increased the number of panicles and yield. In addition, high planting density in late transplanting improved grain quality due to decreased number of grains per panicle. These results suggest that the high planting density is effective to improve yield and grain quality under late transplanting for avoiding high temperature during the ripening period.
