The properties of continuous variation are basic to the theory of evolution and to the practice of plant and animal improvement. Yet the genetical study of continuous variation has lagged far behind that of discontinuous variation. The reason for this situation is basically methodological. Mendel gave us not merely his principles of heredity, but also a method of experiment by which these principles could be tested over a wider range ofliving species, and extended into the elaborate genetical theory of today. The power of this tool is well attested by the speed with which genetics has grown. In less than fifty years, it has not only developed a theoretical structure which is unique in the biological sciences, but has established a union with nuclear cytology so close that the two have become virtually a single science offering us a new approach to problems so diverse as those of evolution, development, disease, cellular chemistry and human welfare. Much of this progress would have been impossible and all would have been slower without the Mendelian method of recognizing and using unit differences in the genetic materials. These great achievements should not, however, blind us to the limitations inherent in the method itself. It depends for its success on the ability to assign the individuals to classes whose clear phenotypic distinctions reveal the underlying genetic differences.

The properties of continuous variation are basic to the theory of evolution and to the practice of plant and animal improvement. Yet the genetical study of continuous variation has lagged far behind that of discontinuous variation. The reason for this situation is basically methodological. Mendel gave us not merely his principles of heredity, but also a method of experiment by which these principles could be tested over a wider range of living species, and extended into the elaborate genetical theory of today. The power of this tool is well attested by the speed with which genetics has grown. In less than fifty years, it has not only developed a theoretical structure which is unique in the biological sciences, but has established a union with nuclear cytology so close that the two have become virtually a single science offering us a new approach to problems so diverse as those of evolution, development, disease, cellular chemistry and human welfare. Much of this progress would have been impossible and all would have been slower without the Mendelian method of recognizing and using unit differences in the genetic materials.

In the second edition of Biometricai Genetics, which appeared in 1971, we set out to give a general account of the subject as it had developed up to that time. Such an account necessarily had to be comprehensive and reasonably detailed. Although it could be, and indeed has been, used by those who were making an acquaintance with this branch of genetics for the first time, it went beyond their needs. We have been encouraged therefore to write an introduction to the genetical analysis of continuous variation aimed primarily at senior undergraduate and postgraduate students, and concentrating on basic considerations, basic principles and basic techniques. This has meant, of course, omitting all reference to some phenomena of more restricted interest, notably sex-linkage, ma ternal effects, haploidy and polyploidy. It has meant, too, that even with some phenomena which have been included, like interactions, linkage and effective factors, the discussions cannot go into full detail. Anyone who is interested, however, can find further information in Biometricai Genetics, to which detailed references have been given where it ap peared that these would be helpful. The order of presentation has been changed with the aim of making it easier for beginners.

Thirty leading international figures celebrate 50 years of achievement in biometry Over the past half-century, biometry has grown from a fledgling application of statistics to a vital and dynamic field that is relevant to some of the most important, substantive scientific and social issues that face us today. Statistical methodology has played a central role in the interpretation of experimental data in such dissimilar areas of biological and medical research as genetics, toxicology, neurology, and clinical trials. It has been applied in both the study and the solution of practical problems in the areas of public health, forestry, animal habitats, environmental contamination, and many more. In this book, 30 leading researchers--many of whom have made outstanding contributions to our understanding of the living world--discuss their specific branches of the subject and reflect on the exciting interaction of mathematics, statistics, and biology that has characterized the growth of biometry. Beginning with a brief history of the International Biometric Society and its journal Biometrics on the occasion of its 50th anniversary, the book goes on to offer a series of views on important developments in the field from two main perspectives: branches of statistical methodology that have played a central role in biometric applications, and branches of biology and medicine that have benefited from these applications. Selected topics are developed in depth, typically with a glance toward the future, and the book is extensively referenced throughout. Advances in Biometry is fascinating reading for students and researchers in applied statistics and mathematics, the biological and medical sciences, public health, and the environmental sciences.

Genetics is the study of genes, heredity, and genetic variation in living organisms while plant breeding is the art and science of changing the traits of plants in order to produce desired characteristics. The fundamental discoveries of Darwin and Mendel established the scientific basis for plant breeding and genetics at the turn of the 20th century. Trait inheritance and molecular inheritance mechanisms of genes are still a primary principle of genetics in the 21st century, but modern genetics has expanded beyond inheritance to studying the function and behavior of genes. The recent integration of advances in biotechnology, genomic research, and molecular marker applications with conventional plant breeding practices has created the foundation for molecular plant breeding. The present book entitled "Key notes on Genetics and Plant Breeding" has been designed to provide a simple umbrella for the multidisciplinary field of modern plant breeding that combines molecular tools and methodologies with conventional approaches for crop improvement. The topics mainly covered includes general genetics, genome organization of crop plants, cytogenetics of crop plants, reproduction and pollination methods, plant breeding methods, population and quantitative genetics principles, biometrical genetics, plant breeding for stress resistance and nutrional quality, genetic engineering and biotechnological tools in plant breeding, plant genetic resources and their regulatory system, seed- classes and certification, economic botany and medicinal plants and Statistical methods and field plot techniques. Hope this volume would be useful for graduate and post graduate students of Agriculture and Biology in all Indian Universities. This will also be useful for those appearing in Competitive examinations such as Agricultural Research Services of the Indian Council of Agricultural Research, National Eligibility Test, Civil Services Examination and other allied examinations.