Rice is the most important cereal crop which feeds more than half the population of the world. It is being grown in more than 144. 641 million ha with a production of over 468. 275 million tons (in 1988). Rice is attacked by a large number of pests and diseases which cause an enormous loss in its yield. Therefore, the major objectives in rice breeding are the development of disease resistance, tolerance to insects, adverse soil water, and drought; and improvement of quality including increased protein content. Tremendous efforts being made at the International Rice Research Institute have resulted in the release of improved varieties. It is estimated that the world's annual rice production must increase from 460 million tons (in 1987) to 560 million tons by the year 2000, and to 760 million tons by 2020 (a 65% increase) in order to keep up with the population growth (IRRI Rice Facts 1988). To achieve this gigantic goal, new strategies have to be evolved. Since the success of any crop improvement program de­ pends on the extent of genetic variability in the base population, new techniques need to be developed not only to generate the much needed variability but also for its conservation. In this regard the progress made in the biotechnology of rice during the last 5 years has amply demonstrated the immense value of innovative approaches for further improvement of this crop.

Section I Establishment of Tissue Cultures, Somatic Embryogenesis, Plant Regeneration, and Ultrastructural Studies.- I.1 Biotechnology in Rice Improvement.- 1 General Account.- 2 In Vitro Culture Studies.- 3 Summary and Conclusions.- References.- I.2 Rice (Oryza sativa L.): Establishment of Callus Cultures and the Regeneration of Plants.- 1 General Account.- 2 Suspension Culture.- 3 Protoplast Culture and Plant Regeneration.- 4 Protocol.- 5 Summary and Conclusions.- References.- I.3 Regeneration of Rice Plants from Suspension Cultures.- 1 Introduction.- 2 Establishment of Root Callus.- 3 Induction and Maintenance of Cell Suspension Cultures.- 4 Plant Regeneration from Suspension Cultures.- 5 Genotypic Variability for Plant Regeneration.- 6 Protocol.- 7 Summary and Conclusions.- References.- I.4 Enhancement of Regeneration in Rice Tissue Cultures by Water and Salt Stress.- 1 Introduction.- 2 Plant Regeneration from Callus Cultures.- 3 Plant Regeneration from Cell Suspension Cultures.- 4 Growth, Water Content, and Proline Accumulation of Callus.- 5 Changes in Polypeptide Patterns in Callus During Stress Treatment.- 6 Discussion and Conclusion.- References.- I.5 Early Events in Zygotic and Somatic Embryogenesis in Rice.- 1 Introduction.- 2 Rice Zygotic Embryogenesis.- 3 Rice Somatic Embryogenesis.- 4 Summary and Conclusions.- References.- I.6 Endosperm Culture and the Regeneration of Triploid Rice Plants.- 1 Introduction.- 2 In Vitro Culture of Endosperm.- 3 Summary.- References.- I.7 Ultrastructural Aspects of Rice Scutellum as Related to Seminal Root Cultures.- 1 Introduction.- 2 Scutellar Epithelium.- 3 Root Culture System.- 4 Ultrastructural Analysis of Scutellar Epithelium.- 5 Multifunctional Nature.- 6 Conclusion.- References.- Section II Hybridization, Embryo Culture, Hybrid Rice.- II.1 Embryo Culture for Wide Hybridization in Rice.- 1 Introduction.- 2 The Genus Oryza.- 3 Seed and Embryo Differentiation.- 4 Embryo Culture.- 5 Other Applications of In Vitro Culture.- 6 Summary and Conclusion.- References.- II.2 Improvement of Tongil-Type Rice Cultivars from Indica/Japonica Hybridization in Korea.- 1 Introduction.- 2 Breeding Procedure of Tongil and Tongil-Type Cultivars.- 3 Conclusions.- References.- II.3 Genetics of Hybrid Sterility in Wide Hybridization in Rice (Oryza sativa L.).- 1 Introduction.- 2 Methods of Investigation.- 3 Evidence of Allelic Interaction for Semi-Sterility in Wide Crosses.- 4 Application of Wide-Compatibility Gene to Hybrid Rice Breeding.- 5 Conclusion.- References.- II.4 Hybrid Rice in China - Techniques and Production.- 1 Introduction.- 2 Heterosis in Rice.- 3 Concept of Three Lines.- 4 Principles and Procedures of Hybrid Rice Breeding.- 5 Breeding for CMS Lines and Their Maintainers.- 6 Breeding for Restorer Lines.- 7 Selection of Parents for Superior Hybrid Combinations.- 8 Hybrid Seed Production.- 9 Future Outlook.- References.- Section III Anther Culture, Haploid Production, and Release of Cultivars.- III.1 Anther Culture for Rice Improvement in China.- 1 Introduction.- 2 Anther and Pollen Culture.- 3 Uses of Pollen Plants in Rice Breeding.- 4 Conclusions.- References.- III.2 In Vitro Production of Haploids in Rice Through Ovary Culture.- 1 Introduction.- 2 Culture Techniques.- 3 Factors Affecting Induction of Haploids.- 4 Embryological Studies.- 5 Characteristics of Regenerated Plants.- 6 Concluding Remarks.- References.- III.3 Factors Affecting Androgenesis in Rice (Oryza sativa L.).- 1 Introduction.- 2 Induction for Sporophytic Development.- 3 Culture Media.- 4 Culture Conditions.- 5 Developmental Stage of Pollen.- 6 Genotype of Donor Plants.- 7 Physiological State of Donor Plants.- 8 Anther Wall.- 9 Differentiation of Callus.- 10 Albinism.- 11 Conclusions.- References.- III.4 Breeding New Rice Strains Through Anther Culture.- 1 Introduction.- 2 Anther Donor.- 3 Media.- 4 Rooting of Plantlets and Transfer to Soil.- 5 Characteristics of New Rice Strains.- 6 Conclusion.- References.- III.5 Huayu 15, a High-Yielding Rice Variety Bred by Anther Culture.- 1 Introduction.- 2 Material and Method.- 3 Results and Discussion.- 4 Summary and Conclusions.- References.- Section IV Protoplast Isolation, Fusion, Culture, and Field Trials of Regenerated Plants.- IV.1 Isolation, Culture and Fusion of Rice Protoplasts.- 1 Introduction.- 2 Protoplast Isolation from sinica (japonica) Rice Cell Suspension Cultures.- 3 The Culture of sinica (japonica) Rice Protoplasts.- 4 Plant Regeneration from Protoplast-Derived Callus.- 5 Protoplast Fusion.- 6 Conclusion and Prospects.- 7 Protocol for sinica (japonica) Rice Protoplast Regeneration.- References.- IV.2 Field Performance of Protoplast-Derived Rice Plants and the Release of a New Variety.- 1 Introduction.- 2 Plant Regeneration from Protoplast-Derived Callus.- 3 Somaclonal Variation.- 4 Agronomic Traits of Protoplast-Derived Plants (Pt1 Plants).- 5 Field Performance of the First Progeny of the Protoplast-Derived Plants (Pt2 Plants).- 6 Field Performance of the Second Progeny of the Protoplast-Derived Plants (Pt3 Plants).- 7 Development of a New Variety, Hatsuyume, by the Protoplast Breeding Method.- 8 Discussion and Conclusions.- References.- Section V In Vitro Mutation and Somaclonal Variation.- V.1 In Vitro Mutation in Rice.- 1 Introduction.- 2 Mutations in Tissue Cultures.- 3 Prospects for Utilization of Somatic Mutations.- References.- V.2 Rice Mutants Resistant to Amino Acids and Amino Acid Analogs.- 1 Introduction.- 2 Selection for Lysine Overproduction with Aminoethylcysteine (AEC) and Lysine Plus Threonine (LT).- 3 Selection for Tryptophan Overproduction with 5-Methyltryptophan (5MT).- 4 Conclusions and Prospects.- References.- V.3 Hydroxy-L-Proline-Resistant Mutants in Rice.- 1 Introduction.- 2 Isolation of Hyp-Resistant Mutants.- 3 Characterization of HYP Mutants.- 4 Characterization of HYP Mutants at Cell Level.- 5 Stress Resistance.- 6 Conclusion.- References.- V.4 Utilization of Somaclonal Variation in Rice Breeding.- 1 Introduction.- 2 Somaclonal Variation in Rice.- 3 Utilization of Somaclones and Crop Improvement.- 4 Conclusions and Prospects.- References.- V.5 Male Sterile Mutants from Rice Somaclones.- 1 Introduction.- 2 Types of ms-Mutant and Their Expressions.- 3 Genetics of the ms-Mutant from Somaclones.- 4 Frequency of ms Variations from Somaclones.- 5 Fertile Revertants from Somaclones of ms Plants.- 6 Conclusion and Prospects.- References.- V.6 Somaclonal Variation for Salt Tolerance in Rice.- 1 Introduction.- 2 Review of Previous Work.- 3 Selection.- 4 Con…