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502. The Plant.—The culms of the rice plant vary in length from two to six feet, usually from four to five feet, depending upon soil, water and methods of culture. The Louisiana Station has found the straw as ordinarily harvested to vary from 1.6 to 2.3 pounds for each pound of rough rice.1 Like the other so-called small grains, rice tillers freely; one seed sending up many culms when conditions are favorable. The spikelets are oneflowered, arranged on short pedicels so as to make a compact panicle in appearance somewhat intermediate between oats and barley. The outer glumes consist of two small scales or bristles, underneath which are two more minute rudimentary ones. The flowering glume is frequently awned. The flower of rice differs from all other cereals, having six stamens instead of three.
503. The Grain.—The fruit or caryopsis of rice is enveloped in the flowering glume and palea, which remain attached when threshed. When in this condition, rice is known as paddy. The flowering glume and palea are usually referred to as the husk or hulls, while the pericarp, testa and nucellus corresponding to the bran of wheat are referred to as the cuticle. The surface of the rice kernel is marked with four longitudinal depressions which give it a fluted appearance. The embryo is not embedded in the kernel but is so exposed that it is easily rubbed off in the process of milling. The cells of the aleurone layer are relatively small in one to two rows. Evidently these cells are removed by the polishing process. (526) The endo- 1 La. Bui. 61, 2nd. ser., p. 392.
sperm is quite hard, and is glassy or translucent, with only here and there white or opaque spots. As in oats, the starch grains are compound. The rice grains usually vary from three-eighths
Longitudinal and cross section of rice kernel: I, cuticle; 2, aleurone layer; 3,endosperm: 4, embryo; unnumbered lines show longitudinal depression In kernel. (After Oodson.)
to two-fifths of an inch in length. The weight of 100 grains may vary from two to three grams, or from 15,000 to 17,000 grains per pound.
504. Composition. — The following table gives the average of ten American analyses of clean rice, and one analysis each of rough rice and rice straw:
i Clean rice is characterized by high percentage of starch and a correspondingly low percentage of other substances, especially crude fiber. Over ninety per cent of the dry matter of rice is nitrogen-free extract, almost exclusively starch. As a source of easily digestible carbohydrates, rice is without a peer among the cereals, and has few equals among food products.
505. Varieties.—There are five types of rice, among which ire lowland rice and upland rice. These have sometimes been considered distinct species, but they are probably only cultivated forms. As might be expected from a plant so widely and anciently cultivated as rice, there are a large number of varieties. In America, however, the varieties have been comparatively few. In the South Atlantic States the varieties chiefly used have been white rice, valued for its early maturity, and two varieties of gold seed rice, so called on account of their golden yellow hulls, differing from each other in the size of the grain, both of which are highly esteemed both because of their quality and the large yield of grain. In the South Central States there are three types of rice recognized, based upon the original source of the seed, viz., Honduras, Japan and Carolina rice. The Honduras rice is the type that has usually been raised, although Japan rice is now raised in large quantities. The grains of the latter are smaller, being shorter but relatively thicker than Honduras rice, and have a thinner hull. Japan rice also tillers more, fifty to eighty seed-bearing culms being not uncommon.1
Red rice is distinguished by the color of the grains, which may vary from very light to dark red, and the color may occur only in the seed coat or throughout the endosperm. This variety, practically wild, is sometimes considered a distinct species, and at least a distinct strain, is a strong and hardier grower than white rice, and will ripen its seed under more diverse conditions. Whenever it gets a foothold, therefore, it rapidly supplants the white rice. Since red rice materially lowers the grade, it causes rice planters great loss and becomes the worst weed that they have to combat.
II. CLIMATE AND SOILS.
506. Climate.—Rice is a tropical or semitropical plant, and attains its best development in a moist, insular climate. In America rice is not raised north of the southern boundary of Virginia, Kentucky, Missouri and Kansas; and very little of it
1 O. E. S. Bui. 131, p. 20.
north of the southern boundary of Tennessee. Its climatic range is similar to that of cotton, being between 450 N. to 380 S. Lat. in the Eastern, and from 360 N. to 380 S. Lat. in the Western Hemisphere. Certain varieties of upland rice are said to be adapted to a somewhat wider climatic range. While upland rice may be raised by methods not dissimilar to that of oat culture, it is neither so productive nor of so good a quality as when raised by irrigation, the method most commonly practiced.
07. Soil.—The principal considerations concerning soil for rice are the ability to irrigate it, to drain it promptly, and to become solid with sufficient rapidity after the water has been removed for the passage of animals and machinery. Different degrees of fertility, however, are recognized, and soils of a clay nature have been found better than those of a sandy or peaty character; although here, as with other crops, a loamy soil with a fair degree of organic matter is desirable. The principal areas in the United States devoted to rice are: (1) the delta land and inland marshes of the South Atlantic States, (2) the alluvial lands along the Mississippi River, and (3) the prairie soil of southwestern Louisiana and southeastern Texas. The practices prevailing in the third area are radically different, both because the topography makes possible larger fields and because the solid subsoil allows the use of self-binding harvesters for gathering the crop. Upland rice may be grown upon any soil that will grow maize or cotton, and the method of culture is not materially different from that of oats or other spring sown grain.
508. Rotation.—A rotation of crops is seldom practiced on the rice plantation, although it is recognized that a rotation would increase the yield of rice per acre; but it would reduce the area grown. One very important reason for a rotation of crops is to free the land of noxious weeds; and planters are being forced to adopt a rotation for this purpose, which consists of interjecting some other crop about once in four years, preferably a cultivated crop, such as maize, or merely permitting the plantation to grow up to dry land weeds.
509. Fertilizers.—Many kinds of fertilizing material are commonly employed in oriental countries; in the United States
Plat of rice field in Raywood plantation showing method of Irrigation in southwestern Louisiana and southeastern Texas. The different tracts are on different levels. Water enters at measuring flume, floods first tract, passes over field levee, floods second tract, and so on until the whole field is flooded. Water is removed through drainage ditch by opening field levees. On this plantation the water in the main canal shown in illustration has been raised a total of sixty-five feet by means of three pumping stations. At the initial station the canal is 1 50 feet wide. (After Bond.)
the land is seldom manured for rice. The irrigation of the land presents problems concerning nitrification and supply of fertilizing constituents from the water that have not been fully