RICE RATOONING - IRRI books - International Rice Research Institute

138 RICE RATOONINGTable 3. Flowering behavior of F 2 segregates and their ratoons.CrossesPlants flowering inTotal Plants flowering Ratoon plants intermediate monthsplants in Mar-Apr flowering in Oct (July through September)(no.)No. % No. %FR13A/Achra108/1FR13A/IR36FR13A/IR50Achra108/1/IR36Achra108/1/IR50IR36/IR5010610610610610610688102103961021064442483540–5041473639–4460556162–5059536361–Table 4. Ratooning ability of some rice varieties, Chinsurah 1981-82.VarietyHills with ratoons (%)Photoperiodsensitivity a 8 cm 12 cmSR26BNC1263NC365Achra108/1TillakkachariBhasamanikBansmoti amanLatisailFR13AKumargoreIR36Pooled varietyPooled cutting heightPooled variety cutting heightPooled errorSSSSSSSSSSIMeanCD (0.05)97929497969488768671618727587.25** b200.0*45.6735.6497969288858789857652618328a S = photoperiod-sensitive, I = photoperiod-insensitive. b Two asterisks indicatesignificance at the 1% level.nonratooning rices, segregates that flowered in 65-100 d and late-maturingsegregates had higher ratooning ability (1, 4). The ratooning ability of 10photoperiod-sensitive rice varieties at cutting heights of 8 and 12 cm abovegroundwas studied at Chinsurah during 1981-82 dry season.Pregerminated seeds were sown 14 Nov 1981 and transplanted 4 Jan 1982.Main crop harvest was completed by May. Ratooning ability was scored 15 d afterharvest at available soil moisture. Photoperiod-sensitive varieties had higherratooning ability and cutting height did not significantly affect ratooning ability(Table 4). Prashar (5) reported ratoon tillers increased when the main crop was cutfrom ground level up to 12 cm, but declined at cutting height beyond 12 cm. Thisgenotypic variability for ratooning could be utilized for improving the ratooningability of rice (3).