RICE RATOONING - IRRI books - International Rice Research Institute

Screening rice genotypesfor ratooning abilityin the Tungabhadra River Projectof KarnatakaK. S. Prakash and B. G. PrakashAgricultural Research Station, University of Agricultural Sciences, 583121,India.In the Tungabhadra River Project, farmers prefer rice cultivars with good grainquality (good grain appearance, short and slender grains, and high milling recovery),responsiveness to high rates of chemical fertilizers, and resistance to insect pests anddiseases. Many recommended and unrecommended rice cultivars are cultivated.The major portion of the area in autumn is occupied by Sona Mahsuri, a latematuring(150-160 d) genotype. In summer, farmers prefer Tellahamsa, a mediummaturing(135-140 d) variety with long, slender grains. Both are, however,susceptible to brown planthopper, so we are trying to replace them with tolerantgenotypes of comparable grain quality.EVALUATING GENOTYPES FOR RATOONING ABILITYMany genotypic differences in ratooning ability have been reported and weresummarized by Chauhan et al (1). However, we felt a need to evaluate genotypes fortheir main crop performance and ratooning ability in the Tungabhadra project area.Main cropTwenty-two promising rice genotypes belonging to medium- and late-maturitygroups were planted in demonstration plots in autumn, 1985. Spacing was 20 cmbetween rows and 15 cm between plants. Fertilizer was applied to the main crop atthe rate of 100 kg N, 22 kg P, and 42 kg K/ha. Days to flowering varied from 98 to135 d. Autumn yields among genotypes varied greatly, but were comparativelylower than summer yields because of brown planthopper incidence and bacterial leafblight.Ratoon cropThe main crop was cut 15 cm above ground. Nitrogen at 50 kg/ ha and P at 18 kg/ hawere applied. The number of regenerated tillers was highest in cultivars that had highmain crop yields. Genotypes ratooned irrespective of their main crop floweringduration.