For several thousand years, farmers have been altering the genetic makeup of the crops they grow. Beginning with individual plant selections suitable for domestication by the first farmers, human selection for desirable features, such as early maturity, shorter stature, or larger seeds has changed domesticated plant species compared with their wild relatives. Major advances in plant breeding followed the rediscovery of Mendel's laws. Breeders brought their new understanding of genetics to the traditional techniques of self-pollinating and cross-pollinating plants. Plant restructuring in wheat and rice by means of dwarfing genes laid the foundation for the Green Revolution that has benefited millions of people worldwide. Continuing with the use of biotechnology to introgress genes of interest, plant breeding is justly one of mankind's most productive occupations contributing to human welfare. Even so, only a limited number of standard plant breeding texts are available. Therefore, we picked up this book with alacrity hoping that it would integrate classical and modern plant breeding approaches.
The 16 chapters in this book aim to provide a broad, general introduction to principles of plant breeding for undergraduate students. It does not cover aspects related to breeding of individual crops. The first chapter on history of plant breeding restricts itself to prehuman food gatherers and the beginnings of agriculture 13 000 years ago. This is an utter disappointment since it does not cover any aspect of plant breeding history. Many of our modern crops were developed in diverse geographical areas by people who lacked an understanding of the scientific basis of plant breeding. But they were able to enforce selection pressures to derive plant ecotypes for various uses. Therefore, a chapter on the origin and domestication of crops is important to understand breeding of a crop. This chapter begins with Vavilov's eight primary centers of origins, Harlan's noncenters, and concludes with a section on changes in plant traits under domestication. There is no information on how understanding origin and domestication can help breeders to achieve their goals. The chapters on genetical basis of plant breeding and quantitative inheritance provide the basics of Hardy-Weinberg law, components of variation, and an extensive treatment of diallel analysis. These chapters are an unexciting treatment of population genetics and do not provide details on its application. The chapter on reproductive systems reads like a glossary, with single sentence explanations for various modes of reproduction. This section could have been improved with a discussion on implications for the choice of breeding methodology. The chapter on selection begins with Fisher's fundamental theorem of natural selection, briefly treats types of selection, continues with factors affecting selection response, pure line theory, and ends abruptly with marker-assisted selection. The chapter "Breeding Methods" is exhaustive and is well organized. It includes methods for selection of parents, handling segregating generations for self- and cross-pollinated crops, population improvement methods, and methods for apomictic crops.
The chapter, "Plant Genetic Resources," includes exploration, collection, documentation, and conservation. A detailed treatment of the establishment of genebanks for food crops at International Agricultural Research Centers and on-line availability of crop descriptor and evaluation data would have added value to this chapter. The chapter on heterosis is very short and should have been included as a section under "Breeding Methods." It includes explanations for the phenomenon of heterosis and hybrid vigor. No details are provided on the use of cytoplasmic male-sterile lines, development of inbreds, testing of hybrid combinations, or methods of hybrid seed production. The chapter on wide crosses introduces the subject in a glossary style by mentioning pre- and post-zygotic isolation mechanisms and methods to overcome such barriers. The chapter, "Ideotype Breeding," takes rice as an example and gives ideal characters for various plant parts. It does not discuss the influential concept of Super Rice with low tillering but sturdier stems and with a larger number of grains per panicle, developed by the International Rice Research Institute. The chapter on breeding for resistance is big and does a good review of resistance to diseases, insect pests, and abiotic stresses. However, it does not discuss incorporation of abiotic and biotic resistances by means of molecular markers.
From the early fifties through the seventies chromosome engineering using allopolyploidy and anueploidy was akin to the biotechnology of today. The introgression of yellow rust resistance from Aegilops comosa into wheat by the 5-B suppression system of Ae. speltiodes, transfer of leaf rust resistance from Aegilops umbellulata to wheat, and use of balanced tertiary trisomics for breeding barley hybrids are some of the elegant examples of the use of cytogenetics in plant breeding. Unfortunately, information in the chapter on polyploidy and chromosome manipulation is presented in an abstract form and does not relate the phenomenon's significance in plant breeding. Mutation breeding has been used to derive several useful cultivars (website http://www-infocris.iaea.org/, verified 27 February 2003, provides details). Much progress is being made combining molecular markers and mutation breeding approaches. The chapter, "Mutation Breeding," provides no details on the choice of mutagens and screening methods to identify mutational events. The chapter on somoclonal variations and transgenics is a good review of this subject area. Notable effort was made by the author to do an extensive list of achievements of transgenics in plant improvement.
The last chapter considers cultivar release and registration procedures and is an inadequate attempt at describing seed regulatory systems in India. The exemplary cultivar testing systems and release procedures implemented by the All India Coordinated Projects deserve detailed treatment. Stringent quality requirements for different seed classes and the increasing role of the private seed sector should have been included.
This book concludes with an epilogue that discusses the need to preserve desirable crop variability and farmer participatory plant breeding. Farmers' participation in breeding gives better understanding of their preferences and allows more accurate selection for specific environments. Increasing preoccupation with farmer participation in breeding should not be allowed to hold up those decisions that still need to be taken by breeders. Though participatory plant breeding is being promoted as a new approach in developing countries, private seed enterprises in North America do this in a regular and methodical manner, which in the end guarantees a market for their products. In addition to large-scale demonstrations, seed companies encourage prospective customers to compare hybrids with their present cultivars on their own farms and with their own farming practices. The sales team often would help the farmer harvest the comparison. In the process, the sales people learn about farmers' needs and desires in hybrids, which they pass on to their breeders (Duvick, D.N. 2001. Biotechnology in the 1930s: The development of hybrid maize. Nature Reviews, Genetics 2:69-74).
We believe this book, if used as an accompanying text for a standard plant breeding course, will be useful for students to comprehend the scientific nature of plant breeding and generality of its principles, diversity of practice not withstanding. Most chapters do not have sufficient explanation of the concepts to be useful to undergraduates. Diagrams to show flow of material from one generation to the next would have been of immense help. An extensive bibliography is included but there are several errors in page numbers. A better description of the principles and phenomena, use of figures and line drawings, standard literature citations, in addition to ensuring that there are no grammatical and spelling errors, would improve the chances of its use outside India.
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