Abstract
The rice plants, cultivated in paddy field, were cut in 6 periods (I-VI), on every 7 days during the maximum tiller number stage (July 17, 1981 : I) to the first heading stage (Aug. 21 : VI). The cutting was conducted at 15cm (H) or 7.5cm (L) in height above the ground. Regrowth plants from the stubbles were investigated on 2 and 5 weeks after cutting, and their yield components were examined after harvest (Oct. 23). 1. The stems which had been grown after cutting and attained to heading were classified into two types as follows : (1) SS (survived stem) : stems which survived in spite of the cutting and attained to heading, and (2) NS (new stem) : tillers newly developed from axillary buds of the cut stems. 2. Regrowth in I-III plots accomplished by development of SS, and V and VI plots are by NS (Table 2). In IV-H plot, shoot apices (young panicles) were cut off in only 5.5% of the whole stems (Table 1), and the regrowth was carried out by both of NS and SS. On the other hand, shoot apices of 65.4% stems were not cut off in IV-L plot, but they did not grow up after cutting, consequently their regrowth were consisted of only NS. 3. After cutting, number of stems per stubble reduced in I-III and IV-L plots, because of death of non-productive tillers (Fig. 3). In V-H and VI-H plots, number of stems increased after cutting because some of the cut stems bore two or three NS. 4. Number of fully ripened grains per panicle was fewer according to delaying the cutting time, and it was lesser in L than H plot (Table 3). And no grain yield was obtained from the panicles of NS in V-L and VI plots. The yield of brown rice became inferior through delaying the cutting time and lower cuttings (Table 4).
