Abstract
The growth and yield components of the second crop (ratoon crop) are affected by the growth of the first crop. The first crop growth was modified by the deep-flood irrigation (DF: 20 days of 15 cm flooding), reduced fertilizer (RF: reduced by 50%), and without treatment (Control). The number of tillers in the second crop was larger in DF and RF than in the Control. The number of days to heading was in the order of DF<RF<Control in the second crop. This suggests that growth control of the first crop advanced the heading time of the second crop. In the second crop, the grain weight per hill and the number of the tillers were negatively correlated with the grain/straw-ratio in the first crop. A heavy grain weight per hill and large number of ratoons were obtained in the plots where the grain/straw-ratio was small, i.e., DF and RF. From these results, it is concluded that the growth, heading and yield components of the second crop were influenced by the crop growth and grain/straw-ratio in the first crop. These observations demonstrated the possibility of attaining a well-balanced high yield in rice ratoon double cropping.
