RICE RATOONING - IRRI books - International Rice Research Institute

RATOONING IN HYBRID RICE 153Table 2. Characters of rice hybrids screened for ratooning ability. IRRI, 1983 dry season. aPlant TotalRegenerationHybrid, variety ht tillers(%) (cm) (no./m 2 )TotalTillers Panicles Panicles(no./hill) (no./m 2 ) (no./hill)Viraldiseaserating bIR19657-34-2-2-3-3A/IR56lR10154-23-3-3A/IR15795-232-3-3-2IR56 (check)IR19657-34-2-2-3-3A/IR36IR19657-34-2-2-3-3A/IR48IR19657-34-2-2-3-3A/IR19661-364-1-2-3IR19657-34-2-2-3-3A/lR19735-5-2-3-2-1IR19657-34-2-2-3-3A/IR19729-67-3IR19657-34-2-2-3-3A/lR13146-45-2-3IR19657-34-2-2-3-3A/lR10781-143-2-3lR19799-17-3-1-1A/IR13420-6-3-3-1lR19799-17-3-1-1A/IR2797-125-3-2-2IR56 (check)MR365A/IR19661-364-1-2-3MR365A/IR19661-131-1-2MR365A/IR48IR56 (check)706981978168938362688381936864809365 279 115162656061646858–5570606967655632328451538932948530 132534634935334832 733737834813101514141510151512121114151411180149179423145171420246401–231274294218213307307866126813818–81099109911010000000100010a Average of 3 replications. b 0 = no incidence, 1 = less than 1% incidence (3).Ratoon height varied from 51 to 70 cm, about 40-50% of the height of the maincrop. Tillers/m 2 ranged from 279 to 515; panicles/m 2 varied from 145 to 401,IR19657-34-2-2-3-3A/IR36 had the most tillers and panicles/m 2 . Hybrid IR19657-34-2-2-3-3A/ IR13146-45-2-3 showed the maximum panicles/ hill (18), whereasIR19657-34-2-2-3-3A/IR48 had the fewest panicles/hill(6). IR56, although it hadvery good regeneration, had only 10-11 tillers/ hill and 6-9 panicles/ hill. In somehybrids with relatively poor regeneration, missing hills were compensated for bymany tillers and panicles per regenerated hill. Hybrid ratoons were more vigorousthan those of IR56. Because the experiment was terminated before maturity.number of tillers and panicles/ m 2 may not reflect yield potential.Judging from flowering time of the ratoons, it appears that hybrid ratoongrowth duration would be 30-50% of main crop growth duration. Hybrids withgood ratooning ability were observed in all three maturity groups. Hybrids withIR19657-34-2-2-3-3A in their parentage had high regeneration and vigorousratoons.Because the parents of the hybrids were not evaluated in the experiment, it isdifficult to project the bases of good ratooning ability. Differential response of somehybrids and IR56 in different replications suggests that, in addition to geneticfactors, cultural management factors may influence ratooning ability.