RICE RATOONING - IRRI books - International Rice Research Institute

RATOONING WITH RICE HYBRIDS 159(Fig. l), soluble sugars decreased, and starch content increased slightly. Averagebud length increased with N rate. Bud length was 2.3 cm with zero N, 3.9 cm with27 kg N/ha, 6.3 cm with 54 kg N/ ha, and 6.6 cm with 81 kg N/ha. The relationbetween N content of main crop stubble and the number of ratoon panicles per culmis shown in Figure 2.Sun et a1 (4) studied the effect of N level and time of application on the mainand ratoon crops of variety Aiyou 2. N applied at 75 and 187.5 kg N/ha increasedmain crop yield but had little effect on the ratoon crop. N applied before the maincrop harvest (34.5 and 69 kg N/ha) did not affect main crop yield (Table 5), butproduced significantly more ratoon tillers and panicles, resulting in higher ratooncrop yield. The yield difference between the two N levels, however, was notstatistically significant. N application time for ratooning was 21 d (T1), 14 d (T2),and 7 d (T3) before main crop harvest. Ratoon tillers at T2 grew significantly more1. Relation between N fertilizer appliedto main crop 14 d before harvest and Ncontent of main crop stubble.2. Relation between N content ofmain crop stubble and effectivepanicles of ratoon crop.