Heterosis and Hybrid Rice Breeding

1 Heterosis in Rice.- 1.1 Historical Résumé.- 1.2 Extent of Heterosis for Agronomic and Physiological and Biochemical Traits.- 1.2.1 Heterosis for Yield and Yield Components.- 1.2.2 Heterosis for Plant Height.- 1.2.3 Heterosis for Days to Flower.- 1.2.4 Heterosis for Dry Matter Production (DM).- 1.2.5 Heterosis for Harvest Index (HI).- 1.2.6 Heterosis for Root Characteristics.- 1.2.7 Heterosis for Photosynthesis, Respiration and Other Physiological Traits.- 1.2.8 Heterosis for Embryo and Seedling Growth.- 1.2.9 Heterosis for Tolerance to Temperature and Other Stresses..- 1.2.10 Heterosis for Biochemical Traits.- 1.3 Combining Ability in Relation to Heterosis in Rice ..- 1.4 Genetic Basis of Heterosis.- 1.4.1 Dominance Hypothesis.- 1.4.2 Overdominance Hypothesis.- 1.4.3 Intergenomic Complementation and Heterosis.- 1.5 Prediction of Heterosis.- 1.5.1 Per se Performance of Parents.- 1.5.2 Genetic Diversity Among Parents.- 1.5.3 Isozyme and RFLP Polymorphism.- 1.5.4 Combining Ability of Parents.- 1.5.5 Mitochondrial Complementation.- 1.6 Current Outlook.- 2 Male Sterility Systems for Hybrid Rice Breeding.- 2.1 Cytoplasmic Genetic Male Sterility in Rice.- 2.1.1 Sources of Cytoplasmic Genetic Male Sterility in Rice.- 2.1.2 Genetic and Molecular Basis of Cytoplasmic Male Sterility..- 2.1.3 Fertility Restoration in Cytoplasmic Genetic Male Sterility in Rice.- 2.1.4 Genetics of Fertility Restoration in Rice.- 2.1.5 Genetic Male Sterility.- 2.1.6 Photoperiod-Sensitive Genetic Male Sterility.- 2.1.7 Thermosensitive Genie Male Sterility.- 2.1.8 Male Sterility in Plants Induced by Chimeric Ribonuclease Gene.- 2.2 Chemically Induced Male Sterility.- 2.3 Current Outlook on Male Sterility Systems in Rice -.- 3 Outcrossing Mechanisms and Hybrid Seed Production Practices in Rice.- 3.1 Rice Floral Organs, Pollination and Fertilization Mechanisms.- 3.2 Natural Outcrossing Mechanisms in Rice.- 3.2.1 Plant Characteristics in Relation to Outcrossing. -.- 3.2.2 Flowering Behavior in Relation to Outcrossing.- 3.2.3 Mechanism and the Angle of Floret Opening in Rice -.- 3.2.4 Floral Traits Influencing Outcrossing in Rice.- 3.2.5 Natural Outcrossing Mechanism in Rice.- 3.3 Guidelines for Hybrid Rice Seed Production.- 3.3.1 Practices for Hybrid Rice Seed Production.- 3.3.2 Flagleaf Clipping, Gibberellin Application and Supplementary Pollination.- 3.3.3 Roguing.- 3.3.4 Harvesting and Threshing.- 3.3.5 Seed Processing.- 3.3.6 Seed Storage.- 3.3.7 Cost of Hybrid Rice Seed Production.- 4 Disease and Insect Resistance in Hybrid Rice.- 4.1 Disease and Insect Resistance Genes.- 4.2 Disease/Insect Resistance of Hybrid Rices in China -.- 4.3 Cytoplasmic Susceptibility to Disease and Insects in Rice Hybrids.- 4.4 Other Considerations for Disease/Insect Resistance of Rice Hybrids.- 5 Grain Quality Considerations in Hybrid Rice.- 5.1 Grain Size, Shape and Uniformity in Rice Hybrids. -.- 5.2 Chalkiness.- 5.3 Endosperm Translucency.- 5.4 Hull and Pericarp Color.- 5.5 Milling and Head Rice Recovery.- 5.6 Cooking and Eating Characteristics.- 5.6.1 Amylose Content of Rice Hybrids in Relation to Their Cooking Quality.- 5.6.2 Gelatinization Temperature of Rice Hybrids.- 5.6.3 Gel Consistency of Rice Hybrids.- 5.6.4 Water Absorption, Volume Expansion and Grain Elongation Ratio.- 5.6.5 Sensory Evaluation for Cooking and Eating Quality of Hybrid Rices.- 5.6.6 Aroma.- 5.6.7 Other Sensory Characteristics of Hybrid Rices.- 5.7 Conclusions.- 6 Accomplishments and Constraints in Hybrid Rice.- 6.1 Hybrid Rice in China.- 6.2 Hybrid Rice Outside China.- 7 Future Outlook.- References.