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states that their experiments have demonstrated the superiority "'or their conditions of the Blue Stem and Fife varieties of common wheat.1 As the result of five years' tests, the Montana Station recommends three Fife varieties (Red, Wellman's and McKissock's) and three durum varieties (Kubanka, Russian 2955 and Wild Goose).2
100. White Varieties.—These varieties are to be found growing in the Pacific Coast States and are largely of the club or square head type. Carleton gives the principal varieties as follows: Australian, California Club, Sonora, Oregon Red Chaff, Foise, Palouse Blue Stem, Palouse Red Chaff, White Winter and Little Club.
III. IMPROVEMENT OF VARIETIES.
101. New Varieties.—The new varieties of wheat in this country have come from three sources: (1) The introduction of foreign varieties; (2) the selection of variations in existing varieties; (3) the crossing of two or more varieties and subsequent selection.
102. The Introduction of Foreign Varieties.—Examples of the introduction of valuable varieties from foreign countries are to be found in Mediterranean, a bearded red winter wheat introduced first in 1819 from the islands of the Mediterranean Sea; Fife, a beardless red spring variety, supposed to have been obtained by selection from a winter variety introduced from Russia; Turkey, a bearded red winter variety from southern Russia; and the club varieties of the Pacific Coast, soft bearded varieties both spring and winter, some of them at least coming from Chile.
103. Improvement by Selection.—Illustrations of improvement by selection are to be found in Fultz, a red-grained beardless variety, selected from Lancaster, a red bearded variety,
1 Minn. Bui. 62 (1899), p. 393. * Eighth An. Rpt. Mont. Sta. (1901), p. 16.
in 1862 by Abraham Fultz, Mifflin county, Penn.; Clawson, a white-grained beardless variety, selected from Fultz in 1865 by Garret Clawson; Gold Coin, a white-grained beardless variety, selected from Diehl Mediterranean, a hybrid with beards and red grains, by Ira W. Green, Avon, N. Y. Probably most of the varieties grown at the present time are the result of simple selection more or less systematic.
104. Varieties Through Crossing.—Probably the best known variety in this country produced by simple crossing is Fulcaster, a red-grained, semihard, bearded variety produced in 1886 by
S. M. Schindel, Hagerstown, Md., by
Diagram showing pedigree
(After carieton.) In the varieties just mentioned only
varieties of the same subspecies have been used in crossing. John Garton of England, William Farrar of New South Wales and W. Rimpau of Germany have produced wheat hybrids by crossing two or more subspecies, as common wheat, durum wheat and spelt. Where crosses cannot be made directly between two subspecies, it may be accomplished indirectly by first producing a hybrid between one type and an intermediate type. Speaking of plants in general, John Garton says that every two species of plants have a gobetween, and given a thousand years he could cross any two plants in the world.
105. The Possibility of Cross-Fertilization.—Hackel states that only about one-third the pollen of an anther is deposited on its own flower, while the rest is deposited into the open air. As the glumes are open upward there would seem to be nothing to prevent the flower below on the same spike from receiving this pollen. Cross-fertilization between flowers of the same spike would seem probable, while cross-fertilization between flowers of different spikes in close proximity would seem possible. In practice, however, it is found that different varieties of wheat grown side by side rarely cross, although it has been pretty definitely proved that they sometimes do so. It has not been satisfactorily explained why varieties do not cross under these conditions. Cross-fertilization can readily be accomplished artificially. It has been suggested that it may be due to the stigma being more receptive to the pollen of its own flower than that of other flowers. Rye, a closely allied species to wheat, seems to cross readily. The pollen is often seen floating over a field of rye at the proper season of the year. The anthers are much larger in rye than in wheat, and therefore the pollen more abundant. The abundance of pollen, the ease with which it floats in the air and the time of day at which the flowers open may be factors in this problem. (49)
106. The Law of Cross-Fertilization.—It is.a generally recognized law that cross-fertilization adds vigor to the offspring, and the many devices by which this is accomplished in plants forms a very interesting study. Hays has suggested that Darwin's dictum that nature causes benefits to arise from crossing and abhors self-fertilization may not apply to all plants. He would state the law thus: "Nature abhors a radical change which would require species to cross in much closer or in much more radical relationship than is their long-established habit."
107. Importance of Crossing as a Method of Improvement.—
Mendel found that hybrid peas selected to one type were soon stable. Mendel's Law worked out formally gives the following results as applied to one characteristic of the artificial hybrids allowed to self-pollinate during a series of years.
Graphic expression of the results of an experiment In developing from a single hybrid plant No. 1814 (produced by crossing a plant of Fife with one of Blue Stem), two varieties, one having smooth and the other hairy chaff. (After Hays.)
Since wheat hybrids naturally self-pollinate, it w< aid be expected that they would follow the same law, and Spili-jan found
this to be the case. Hays reduced some hybrids to uniform type in four generations. His hybrid varieties based on single mother plants of the fourth generation breed true to the botanical types of the mother plant. Whether the correlated characteristics combined in making up the unit of higher value per acre will continue their united excellence has been questioned. Hays' experience indicates that at least a part of the hybrids which show most vigor in value per acre during the first several years after the hybrids are formed will continue to yield well of good grain. Mendel's results add assurance to the hope that at least part of the complex compound of characters formed in producing a lot of wheat hybrids will remain stable. Hybrids made by Saunders, Hays and others and widely distributed retain their characteristics apparently unchanged.
108. Method of Finding and Testing New Strains or Varieties. —The methods of improving wheat by experiment and seed stations now recognize the individual wheat plant as the unit from which selections are made. From whatever source the seed is obtained, whether from crossing, by selection from a field or simply from the bin, seeds are planted individually in rows any suitable distance apart,—usually four by four inches for spring wheat and five by five for winter wheat. The larger the number of individual plants the better. If any plants are found among those thus grown that possess characteristics desirable to perpetuate, one hundred seeds, more or less, are planted as above indicated in order to determine the ability of the selected plant to transmit its characteristics or in the case of cross-bred varieties by continued selection to fix the type. This group of plants from a single parent has been given the name of centgener.1 Centgeners of a single strain are raised for three or more years, when, if found promising, all the seed, or as much as may be necessary, of the produce of the centgener, except the best one or more plants, is sown in small plats to test its adaptability under field conditions. If found satisfactory, the seed is rapidly multiplied and distributed among farmers and commercial seed growers. The plants reserved become mothers of centgeners with the hope of obtaining still further improvement.