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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 not 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.
The individual plant is the complex resultant of two forces, heredity and environment. Those characteristics of wheat which are acquired from environmental influences and which are transmissible from generation to generation of plants may be considered as belonging to heredity, a subject fully treated in the preceding chapter. The natural environment, consisting of soil and climate, is a pronounced factor in the growth of wheat, independent of the artificial modifications known as cultivation. The latter subject is treated in a later chapter.
Soil.-There are mechanical and chemical differences in soil that exert a varying influence upon the quantity and quality of wheat. The effect upon yield is more pronounced than that upon quality. In North Dakota 39 different samples of Blue Stem and Scotch Fife wheats of known history were obtained from farms representing the varied soils of the state. Sown upon the same soil, all gave approximately the same results in yield and quality of grain and straw. They also matured at the same date, and had like periods of development. Another experiment was made in which seed raised from one soil was hand picked to uniformity, and then grown upon various types of North Dakota soil in different portions of the state. The resulting grain and straw showed great variation.” Similar experiments were made in Indiana and Maryland" with practically the same results.
The soil has been a great factor in determining the distribution of wheat. Much of the wheat of the United States is grown upon glacial drift soil. There are two general types of this soil: The uplands, which are usually of a light-colored, tenacious clay; and the lowlands and prairies, which have a
* N. D. Bul. 17, pp. 89-95.
* Ind. Bul. 41
dark, loamy, organic, friable soil. Common bread wheats are
usually grown on black soils. These soils are not well adapted to fall wheat, however, for it is apt to winterkill. Durum wheats thrive best in alkaline soils rich in nitrogenous matter. Sandy bottom land is best adapted to the production of soft wheat. Richardson attributed the low protein content of some American wheat to a deficiency in soil nitrogen. The ash of wheat stands next to the gluten in variability, and the factor most concerned in its variation is the soil.
The lined districts show where durum wheat will succeed best and the dotted districts where it may be grown with grain of less quality.
Climate.—Seasonal differences are included under this subject, because their effects are the same in kind as those of climatic differences. Certain climates produce certain corresponding characteristics in wheat, regardless of what the soil conditions are. The protein content of wheat, and correspondingly its moist and dry gluten, is extremely sensitive to environment of a meteorological nature. The starch content is also sensitive, but in an inverse ratio. Climate varies from
year to year in any locality, and it is well known that this causes corresponding variations in wheat, even under similar soil conditions. In the gluten content is seen the first reflection of a change in environment. The claim has even been made that a number of varieties of wheat grown under uniform soil and meteorological conditions would yield relatively the same percentages of gluten, however much these might vary from the normal.”
Northern grown seed of spring wheats will mature plants earlier than southern-grown seed of the same variety, but the reverse is true of fall-sown grain, which ripens earlier from southern-grown seed.” Wheat raised on the sea coast develops special characteristics due, at least in part, to climate. In southern Russia Arnautka wheat attains its highest perfection only when grown within a limited area bordering the Azov sea. All wheat raised directly on the Pacific coast in western United States is soft, damp, dark and has a very thick skin. It shades off gradually to that grown inside of the coast range and protected from the fogs. This inland grain is bright, very hard and dry, and has a thin skin.
Regions having cold winters produce most of the world's wheat. Marked exceptions to this are California, Egypt and India. Small, hard, red grains having a high nitrogen content are usually found in a climate characterized by extremes of temperature and moisture. Climate and season both affect the length of the period of growth. This has an important influence on the chemical composition of wheat, for a short season of growth raises the percentage of protein and lowers that of starch. In Canada, a shorter period of time is required for maturity in northern latitudes. The growing season of Winnipeg is about one week longer than that prevailing 500 miles farther north.
It has been said that “other things being equal, varieties which have become acclimated are to be preferred.” While this is true, it still leaves us the case where other things are not equal. Nearly every climate has its disadvantages for wheat growth, and, as we have seen, wheat always adapts itself to overcome these disadvantages. The greater they are, the
1 O. Bul 129, p. 5. 2 Yearbook U. S. Dept Agr., 1901, p. 235; S. C. Bul. 56, p. 12.