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pose, show the following results for three years 1889 to 1891 inclusive:
Total crop as liar- Yield of dry matter
Type Variety vested per acre per acre
Dent White Horse-tooth1 35,195 4,79$
Flint Local I9,197 2,893
Sweet Early Crosby 16,908 2,420
During five years the average yield of dry matter has been for the dent variety 5,036 pounds and for the flint variety 4,224 pounds. The Pennsylvania Station2 found that the dsnt fodder yielded forty-five per cent more dry matter than flint fodder. The flint variety contained a considerably larger percentage of protein and smaller percentage of crude fiber. At Cornell Station 8 Sibley's Pride of the North yielded ten per cent more dry matter than an eight-rowed flint. Ontario Agricultural College compared the feeding value of dent maize and sweet maize silage and found the latter slightly superior in feeding value—believed to be due to greater palatability in this case— but the increased yield of dent maize more than compensated for the decrease in feeding value.4
Varieties originating in the South Atlantic and South Central States are frequently sold in the North Atlantic and North Central States as silage maize. The season of growth being longer than northern grown varieties, they continue to grow later in the season, thus often producing a greater yield of silage per acre than those varieties grown principally for their grain. These so-called silage varieties do not produce as large a proportion of ears to stalk and leaves, and in many cases the per cent of water is higher, thus requiring the handling and storing of more tons of silage for an equal amount of dry matter and of food value. When silage is put up too green its keeping quality and
1 Southern variety.
2 Penn. Rpt. 1891, p. 30. S Cornell Bui. 4, p. 51.
4 Ont. Agr. Col. and Expt. Farms Rpt. iSy7, p. 83.
food value are lessened. (353) For silage, it is generally desirable to plant a variety which will develop a normal proportion of ears and that will get as mature as it is possible for maize to be when put in the silo. (349)
250. Comparative Yield of Dent and Flint Maize.—Almost all of the field maize of the United States, comparatively speaking, is of the dent type. Flint maize requires a smaller number of days to mature a crop; hence it is used in the more northern latitudes and at higher altitudes. It is the common field crop of New England. Each of these types has its place, but wherever the common varieties of dent maize will ripen flint maize usually is not desirable. For example, at the Pennsylvania Station eleven varieties of flint maize and fifteen varieties of dent maize have been tested from one to three years. The altitude is 1,200 feet; the season, therefore, is comparatively cool and short, and not especially adapted to the growth of dent varieties. The following table gives the yield of dry matter in pounds from ears and stover:
Ears . . . 1,750 3.012
IMPROVEMENT OF VARIETIES.
251. Pollination.—Maize is said to be wind-fertilized, since the extremely abundant pollen is carried long distances by the wind and often deposited upon silks of ears quite remote from the tassel bearing the pollen. Notwithstanding the large amount of observation and experiment, the extent to which maize is cross-fertilized and to what extent it is self-fertilized in actual practice has not been clearly established. It is believed by many, however, that since the pollen appears to develop slightly in advance of the silks of the same plant, and since the tendency of the currents of air would be to carry the pollen away from the plant producing it, that cross-fertilization is the rule and self-fertilization the exception. It has been clearly established, however, that both cross-fertilization and self-fertilization can readily be effected. Artificial or hand pollination usually does not produce as good results as when pollination takes place in the natural way.
The ovules are fertilized in order of sequence from butt to tip. Since the tip grains develop last, the tip of the ear is the most variable, due to variations in soil, cultural or seasonal conditions. It is probable that the filling out at the tip of the ear should be looked upon as the result of environment more than as an hereditary or variety characteristic. (243)
252. Influence of Current Cross.—The influence of pollen upon the grain or fruit which immediately develops, called xenia, has received considerable study especially in maize. That the character of the male pollen may affect the endosperm of the fertilized ovule is certain. When sweet maize is crossed with dent pollen, the resulting grains have the appearance of flint grains, being neither dented nor wrinkled, and have the taste of dent maize. Sweet maize shows the influence of the current
Black Mexican aweet-whita dent cross. Ear I is Black Mexican sweet maize which was used as the male parent. Ear 2 is a white dent variety used as the female parent. Ear 3 shows the intermediate result of the cross, grains from which were planted to produce ears 4 and 5. Ear 4 was from the wrinkled or sweet grain of ear 3. Ear 5 was grown from the dent grains of ear 3 (after McCluer).
cross when pollinated by dent maize with such certainty that grains which do not show the effect may be depended upon to produce a pure product the next year.1 When sweet maize, is
'R. I. Rpt. 1901, pp. 227-244.
the male and dent maize the female parent, McCluer1 has shown both sweet and dent grain in the current cross, and that the dent grain when grown would show sweet characters. There is a strong tendency for color, where it is a character of the endosperm, to show in the current cross.
Webber has shown that the aleurone layer may be affected by the current cross. Cuzco, a soft variety, with heliotropepurple color in the aleurone layer, was crossed upon several varieties of dent maize, and grain resulting from such fertilization contained the same or similar color in the aleurone layer.2 The immediate effect of pollen upon the color when the color is in the seed coat, as in calico maize, is denied by some, and the observed instances have been explained by assuming that the seed of the female parent was impure.
253. Degree of Close Breeding.—There may be several degrees of closeness in breeding maize: (1) Between pollen and ovules of the same plant; (2) between pollen and ovules of plants grown from seed from the same ear; (3) between pollen and ovules of plants grown from seed from different plants of the same variety. The closeness of relationship of the plants furnishing the seed may vary between very wide limits. They may have had a common ancestor but one generation back, or they may have been unrelated in one or both ancestors for many generations; (4) between pollen and ovules of plants grown from seed of different varieties; (5) between pollen and ovules of plants grown from seed of different types.
254. Close Breeding.—Since cross-fertilization appears to be the rule in maize, it is generally considered desirable to avoid any practice which would induce close-fertilization. (106) Hopkins states that he has secured data pointing toward an injurious effect of close-pollination and recommends cross-pollination in
1 11i. Bui. 21, p. 87.
* Xenia, or the immediate effect of pollen in maize. U. S. Dept. of Agr., Div. Veg. Phys. and Path. (1900) Bui . 22.