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limited to the few very best wheats, for a fairly large number of varieties can be used profitably for special characteristics. The great advantage of hybridization is shown in three effects, all of which aid in accomplishing more rapidly the results aimed at in selection. It makes it possible immediately and directly to combine the qualities of two different plants in one; it immensely increases that variation which alone makes selection possible; and it imparts greater vigor to the offspring. Hybridizing does not always give a progeny im
mediately averaging better than the parents. In many cases the first progeny will average much poorer than either parent. Its great value lies in throwing together qualities and multiplying variations, both of which may be developed by selection. This greatly increased variation has been explained on the ground that "the wheat plant being so closely self-fertile, there is within it, lying dormant, a wonderful power to vary (a power far greater than in plants cross-fertilized in nature), which is thrown into action when different varieties are artificially crossed."1 As to these varieties Hays says: "The further they have departed from ancestral characteristics and formed diverse qualities, the more likely will their progeny exhibit new characteristics made up by combining those which have become so radically different in the two parents."2 There
1 Carleton, Basis for Improv. of Amer. Wheats, p. 73.
also arise characteristics so new in kind and degree that they can hardly be considered as a mere combination of any characteristics found in the parents. All of the so-called "botanical" classes of wheat have been produced by hybridizing two varieties, a fact which "certainly indicates blood relationships between the classes of wheats."
Since the qualities originated by hybridization must be developed by selection, it may take years before the value of the hybrid can be determined. The advantage in large numbers lies in the fact that "only one individual in several thousand has marked power to produce a valuable strain." These individuals have been called the "Shakespeares of the species," and the labor of eliminating by selection all of the other individuals is 99 times that of producing the hybrids.1 By the usual method, the seeds to be tested and selected are planted individually in rows 4 or 5 inches apart. If any promising plants develop, 100 seeds from each are again planted. These groups of plants from single parents are called centgeners. By means of selection, crossbred wheats can thus be reduced in four or five generations to a type so uniform that little or no variation will occur among plants in the field. Whether they will retain their acquired characteristics has been questioned. Hybrids originated by Hays and Saunders seem to do so. The question as to whether wheat will deteriorate under self-fertilization is still an open one.
In breeding a variety of wheat, the ideal to be held in mind constantly is '' that it yield the largest possible amount of grain of the best quality for the purpose desired under given conditions."2 In such a course botanical appearances seemingly will take care of themselves.
Historical.—The sexuality of plants was proved experimentally by Camerarius (1691). The first recorded hybrid was produced by Thomas Fairchild (1719), an English gardener, who crossed the carnation with the sweet william. The publications of Koelreuter (1761) paved the way for the work of Thomas Andrew Knight (1800), the eminent English plant physiologist, who has been called the father of plant breed1 Hays, Yearbook U. S. Dept. Agr., 1901, p. 229. 'Scofleld, Algerian Durum Wheats, p. 7.
ing. The first hybrid produced in the United States was probably a pear (1806). The importance of hybridization in relation to variation was demonstrated by Naudin and Nageli (1865).
The pioneer producer of wheat hybrids in America was C. G. Pringle of Charlotte, Vt. He began his work in 1877, and several varieties have received his name, some of which have become standard. Pringle's Defiance has been a rust resistant variety of California since 1878. During his connection with the Colorado agricultural college A. E. Blount produced quite a large number of hybrids, some of which are now well known in the United States and are also among the most valuable varieties in Australia, both as field wheats and as parents of native hybrids. The most important are Amethyst, Improved Fife, Hornblende, Gypsum, Blount's No. 10, Felspar, Ruby and Granite.
The director of the experimental farm at Ottawa, Canada, Dr. William Saunders, began hybridizing wheats in 1888. His main object has been to procure early ripening varieties, and he has attained success by hybridizing American and Russian races. Preston and Stanley are two of his best productions. In the main these hybrids have been produced in the most simple way. A. N. Jones of Newark, N. Y., practicing composite crossing, though always with quite closely allied parents, has done the most important work in wheat hybridization in this country, and his varieties are now the most widely used of all recent American wheat hybrids. The two features characteristic of his work have been composite methods, and high gluten content as an ideal. The nature of the soil and climate of eastern United States is such as to produce soft and starchy wheats. His efforts have been to raise the standard of eastern varieties as to gluten, and he has largely succeeded. Winter Fife and Early Red Clawson were the two most popular of his first varieties. Early Genesee Giant, another well-known variety which he originated, is widely grown in New York and Pennsylvania. It has no ancestors outside of the common bread-wheat group. This seems to be a weak point in Jones' method of procedure, for the most advantageous composite crossing is supposed to be with varieties of entirely different wheat groups.
This gives by far the greatest variations in degree and number, and gives qualities not otherwise obtainable. For example, the highest degree of non-shattering must be obtained from spelt or emmer, while the quality of resistance to leaf rust is best acquired by crossing with the durums. Jones' Winter Fife could not be grown in the Palouse country on account of its shattering, though it yielded 60 to 65 bushels per acre.
The Garton Brothers of England and William Farrer of New South Wales have extensively practiced crossing the different wheat groups. Every variety and every intergradation results from such crossing. A local variety may acquire, not only rust resistance and tenacity of chaff by intercrossing with a spelt and a durum, but also greater fertility of the head drawn from the spelt, and increased vigor of the seed, which produce a higher yield. These, and increased hardiness and gluten content, are practical results attained by the Garton Brothers. William Farrer has done an immense amount of excellent work in improving Australian wheats, especially as to rust resistance. The most important work in breeding cereals on the continent has probably been done by W. Rimpau of Schlanstedt, Germany, though his work is not generally characterized by composite methods. The Vilmorins have also done work in this line. The Dattel, one of the most widely distributed varieties of wheat around Paris, was originated by them.
Breeding Experiments have been carried on in the Kansas wheat belt for some years, and extensive co-operative work in this line has been taken up with the experiment stations in different wheat growing states, particularly in Texas, Kansas, South Dakota, Minnesota and Maryland. Efforts are being made to secure a variety that will ripen a few days earlier, so that by sowing two varieties the harvest period can be lengthened, and the danger of green cutting and shattering be avoided. Wheat and rye have been successfully hybridized by a number of experimenters, but as yet with no valuable results.
Experience has taught that the most successful and practical way to fight disease is to aid natural selection in producing disease-resistant or immune plants, rather than to attempt to cure the disease. "As a foundation for rational wheat improvement, a knowledge is required of the characteristics and needs of different wheat districts, and the characteristic qualities of the natural groups of wheats." A century ago wheat was wheat, but now thousands of varieties have been bred up which thrive best under the local conditions for which they were bred, and often they satisfy conditions, uses and tastes not in existence a century ago. The entire wheat harvest of the world is being improved. The value of this work in proportion to its cost must appeal to everyone, and indicates its permanency. Luther Burbank made the statement that if a new wheat were bred that would yield only one grain more to each head, Nature would produce annually, without effort or cost for man, 15,000,000 extra bushels of wheat in the United States alone.
The conclusions of scientists seem to be that varieties will hot wear out or materially change if the same conditions which made them excellent are kept up. If special care was exercised to produce an artificial variety, this care must be continued, or it will deteriorate. The improvement of wheat by breeding is no longer a theory, as in the time of Darwin, but an established fact.