Imágenes de páginas

Aussian Velvet

No 87.


Winter Fire
Iron Surau

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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, 1 red-grained, semihard, bearded variety produced in 1886 by

S. M. Schindel, Hagerstown, Md., by Mediterranean

crossing Fultz and Lancaster. (103) rules

An example of continued crossing with different varieties for several generations

is to be found in Early Genesee Giant, · Hybrid Winte Pule

a bearded, red-grained variety produced

by A. N. Jones, Newark, N. Y. Jones' Hybrid Iron Straw

Winter Fife, Early Red Clawson and

many others have been produced in this Diagram showing pedigree of Early Genesee Giant.

way. (After Carleton.)

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

Early Genesee Giant

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 selectea 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.

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Since wheat hybrids naturally self-pollinate, it we uld be expected that they would follow the same law, and found

this to be the case.

Hays reduced some 1893 1894 1895 1896 1897 1898 1899

hybrids to uniform type in four generations. His hybrid varieties based on

single mother plants Graphic expression of the results of an experiment in

of the fourth generadeveloping from a single hybrid plant No. 1814 (pro tion breed true to duced by crossing a plant of Fife with one of Blue Stem), two varieties, one having smooth and the other

the botanical types hairy chaff. (After Hays.)

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

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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 Method of planting wheat in field nur.

sery of Nebraska Experiment Station. from a single parent has been (From photograph by Lyon.) 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.

1 Plant Breeding. By Willet M. Hays. U. S. Dept. of Agr., Div. of Veg. Phys and Path. Bul. 29 (1901), p. 46.


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109. Conditions of Successful Wheat Culture.—The yield and quality of wheat, and hence its successful growth, agriculturally considered, depend mainly upon these six conditions: (1) climate, (2) soil (including fertilizers), (3) variety, (4) methods of cultivation, (5) liability to disease, and (6) attack of insect enemies.

110. Effect of Climate Upon Geographical Distribution. According to the tenth census seventy per cent of the wheat of the United States was grown where the average January temperature was below freezing; eighty-five per cent was grown where the average July temperature was between seventy and eighty degrees, and sixty-five per cent where the mean annual temperature was between forty-five and fifty-five degrees. Too much weight must not be attached to this, as the soil, particularly in respect to its ease of cultivation, has greatly affected the distribution of wheat. Most of the wheat of the world, however, grows in regions of cold winters, although there are some noted exceptions, as California, Egypt and India. Taking the world at large, and including both spring and winter varieties, wheat has a very wide climatic range. Its range of successful culture, also, seems to be constantly extending northward, whether through climatic adaptation or from other causes seems less clear.

III. Effect of Climate Upon Quality. Localities having widely different climate and soil have their peculiar varieties, which differ somewhat in composition but much more in physi.

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