Rice is the most important food crop of the developing world and the demand for it is growing. Provided here is a concise account of hybrid breeding in rice, a newly deployed breeding approach to increase the yield. Research on heterosis, male sterility systems, outcrossing mechanisms, disease/insect management, and grain quality considerations in hybrid rice are reviewed. Heterosis and Hybrid Rice Breeding contains a wealth of useful information for practicing hybrid rice breeders, seed producers, researchers, and students of plant breeding.
1 Heterosis in Rice
1.1 Historical Resume
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