R. Frankel – författare

view than its own proper males should fecundate each blossom." ANDREW KNIGHT Philosophical Transactions, 1799 Pollination mechanisms and reproduction have a decisive bearing upon rational procedures in plant breeding and crop production. This book intends to furnish'' under one cover an integrated botanical, genetical and breeding-methodologi­ cal treatment of the reproductive biology of spermatophytes­ mainly angiosperms; it is based on an advanced topical course in plant breeding taught at the Hebrew University of Jerusa­ lem. We have tried to present a coverage which is concise, but as comprehensive as possible, of the pollination mechanism and modes of reproduction of higher plants, and to illustrate topics, whenever practicable, by examples from cultivated plants. Nevertheless, some relevant publications may have escaped our attention or may not be mentioned because of various limitations. The book is organized into three parts. The first part starts with an evaluation of the significance of the different pollination mechanisms for plant breeding and crop produc­ tion, describes modes of reproduction in higher plants and discusses ecology and dynamics of pollination. The second part is devoted to crops propagated by self pollination and describes specific breeding procedures for such crops. The third part details sexual reproduction in higher plants and handles three mechanisms involved in the prevention of self pollination and their utilization in plant breeding: sex expres­ sion, incompatibility, and male sterility.

view than its own proper males should fecundate each blossom." ANDREW KNIGHT Philosophical Transactions, 1799 Pollination mechanisms and reproduction have a decisive bearing upon rational procedures in plant breeding and crop production. This book intends to furnish' under one cover an integrated botanical, genetical and breeding-methodologi­ cal treatment of the reproductive biology of spermatophytes­ mainly angiosperms; it is based on an advanced topical course in plant breeding taught at the Hebrew University of Jerusa­ lem. We have tried to present a coverage which is concise, but as comprehensive as possible, of the pollination mechanism and modes of reproduction of higher plants, and to illustrate topics, whenever practicable, by examples from cultivated plants. Nevertheless, some relevant publications may have escaped our attention or may not be mentioned because of various limitations. The book is organized into three parts. The first part starts with an evaluation of the significance of the different pollination mechanisms for plant breeding and crop produc­ tion, describes modes of reproduction in higher plants and discusses ecology and dynamics of pollination. The second part is devoted to crops propagated by self pollination and describes specific breeding procedures for such crops. The third part details sexual reproduction in higher plants and handles three mechanisms involved in the prevention of self pollination and their utilization in plant breeding: sex expres­ sion, incompatibility, and male sterility.

When trying to solicit authors for this book it became apparent that the causal factors for heterosis at the physiological and biochemical level are today almost as obscure as they were 30 years ago. Though biometrical-genetical analyses point to dispersion of complementary genes - not overdominance - as the major cause of the phenomenon, plant breeders'' experience still suggests a cautious, pragmatic approach to the dominance-overdominance controversy in breeding hybrid cultivars. Thus we are faced with a striking discordance between our limited comprehension of the causal factors and mechanism of heter­ osis on the one hand, and the extensive agricultural practice of utiliza­ tion of hybrid vigor on the other. Such utilization is the result of the economic value of hybrid combinations displaying superior yields and qualities as well as stability of performance, of benefits derived in breeding programs, and of the enhanced varietal protection of proprietary rights. No comprehensive and critical analysis of the phenomenon of heterosis in economic plants has been published for the last three decades since the now classical book Heterosis, edited by J . W. Gowen (Iowa State College Press, Ames, Iowa, 1952). The present book attempts to fill the gap and to assess the status of our present knowl­ edge of the concept, the basis, the extent, and the application of heterosis in economic plants.