The relation between N applying for bud development (NABD) and ratooning ability in hybrid mid-rice were studied with the hybrid Shan You 63 and Kei You 3. The results were as follows: The NABD at 15 days after full heading of the main crop could not increase the percentage of alive bud of the 2nd and 3rd nodes from top, but could increase those of 4th and 5th nodes from top.
From 1995 to 1996, the relationship between the number of grains per panicle among varieties of main crop and their ratooning ability in hybrid mid rice with 19 varieties of rice as materials was studied.
The relation between N applying for bud development (NABD) at different days after full heading of main crop and the ratooning ability in hybrid mid rice was studied with the hybrid K-You 5. The results are as follows: the effect of the NABD appears around 10 days after full heading of main crop;