The Superiority of Line Breeding Over Narrow Breeding (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1909 edition. Excerpt: ... CONTENTS. Piage. Introduction 7 Three principal types of reproduction 8 Effects of restriction of descent 9 Agricultural improvement by increase of uniformity 11 'Vegetative propagation the most effective method of line breeding 11 Vegetative propagation depends on longevity 11 Other methods of line breeding 14 Relation of self-fertility to vegetative propagation 15 In-and-in breeding 17 Self-fertilization supplements broad breeding in natural species 18 Broad breeding and line breeding in the same species 19 Line breeding a system of propagation 20 How selection improves line-bred varieties 24 Selection a conservative process 24 Uniformity not a normal condition of heredity 27 Two forms of mass selection 28 The "running out" of varieties-29 Rejuvenescence of varieties 30 A balance between broad breeding and narrow breeding 31 Avoidance of unnecessary uniformity 32 The "fixing of characters" by line breeding 35 Recurrence of diversity in crosses between line-bred groups 36 Conclusions 37 Index 41 146 THE SUPERIORITY OF LINE BREEDING OVER NARROW BREEDING. INTRODUCTION. None of the applications of the science of evolution to the art of breeding has been the subject of so much study, experiment, and discussion as the relative merits of inbreeding and cross-breeding. Nevertheless, opinions remain as discordant as ever, for some experiments appear to indicate that cross-breeding is better than inbreeding, while other experiments seem to show quite as definitely that inbreeding is better than crossing. Experiments are our means of securing answers to scientific questions. When experiments appear to give contradictory or equivocal answers we know that we have not asked our questions in the right way. We are warned that there are more differences among...