Plant-Breeding; Being Five Lectures Upon the Amelioration of Domestic Plants (Paperback)

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: production of fixed and well-marked races." I may remark again that, because of the- unequal and unknown powers of the parents, we can never predict what characters will appear in the hybrids. This fact was well expressed by Lindley a half century ago, in the phrase, " Hybridizing is a game of chance played between man and plants." V. Characteristics Of Crosses. Bearing these fundamental propositions in mind, let us pursue the subject somewhat in detail. We shall find that the characters of hybrids, as compared with the characters of simple crosses between stocks of the same variety, are ambiguous, negative, and often prejudicial. The fullest discussion of hybrids has been made by Focke (see Lecture IV.), and he lays down the five following propositions concerning the character of hybrid offspring: ? 1. " All individuals which have come from the crossing of two pure species or races, when produced and grown under like conditions, are usually exactly like each other, or at least scarcely more different from each other than plants of the same species are." This proposition,' although perhaps true in the main, appears to be too broadly and positively stated. 2. " The characters of hybrids may be differentfrom the characters of the parents. The hybrids differ most in size and vigor and in their sexual powers." 3. " Hybrids are distinguished from their parents by their powers of vegetation or growth. Hybrids between very different species are often weak, especially when young, so that it is difficult to raise them. On the other hand, cross-breeds are, as a rule, uncommonly vigorous; they are distinguished mostly by size, rapidity of growth, early flowering, productiveness, longer life, stronger reproductive power, unusual size of some special organs, and similar characte...