Studies on evaluating the potential for recurrent selection in a rice population
1990
Orapin Watanesk
Potential of recurrent selection was evaluated in the rice population CP 103 (the composite IR 38499) cycle 1 at IRRI. Days to 50 % flowering, male sterile plants per plot (in S1 lines), lodging incidence, plant height, yield components, adjusted yield and some grain quality traits were studied. Broad-sense heritabilities from components of S1, S3 and S4 generations were high for plant height, grain quality and 100-grain weight. S1 generation showed lower values than S3 and S4 generations. S1 generation showed less expected genetic gain from selection assuming 20 % selection intensity for all characters than S3 and S4 generations. The high association between S1 and S1-derived S3 lines and between S1 and S1-derived S4 lines in all characters indicated that S1 lines could predict both S3 and S4 derived lines. However, the days to 50 % flowering, percentage of unfilled grains and adjusted yield showed inconsistent correlation between the generations. In every generation, kernel length was highly and positively correlated with kernel shape and 100-grain weight, plant height being highly associated with spikelet number per panicle. Panicles per hill were negatively correlated with plant height and spikelet number per panicle. Low correlation was obtained between yield and yield components. Only S1 generation showed highly positive correlation between yield and spikelet number per panicle. Wide variation among S1 lines for all characters was observed in both seasons. Superior lines showed higher values than IR 36 and/or IR 68. This indicated that S1 recurrent selection would be effective in improving this population.
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