1. Hard kernel type Also called flint type. Seeds are mostly square and round, the top and around the endosperm are horny, only the center of the near-embryo part of the powder, so the appearance of translucent glossy, hard and full. The color of the grain is mostly yellow, or by, red, purple and other colors. Seed quality is good, is China's long-term cultivation of more types, mainly for food grain.
2. Horse-tooth shape is also called horse teeth type. Seeds flat rectangular, because the top of the powder than the sides of the horny dry faster, so the top of the center concave, shaped like a horse's teeth, so the name. Seed skin wrinkles rough opaque, mostly yellow, white, a few purple or red, poor eating quality. It is the most cultivated type in the world and in China, suitable for the manufacture of starch and alcohol or as fodder.
3. Semi-horse-tooth type is also called intermediate type. It is from the hard grain type and horse tooth type corn hybrid. The top of the kernel depression is shallower than the horse-toothed type, and some are not depressed but only white speckled. The powdery endosperm at the top is less than the horse-toothed type but more than the hard-grain type, the quality is better than the horse-toothed type, more cultivated in China.
4. Powdery type is also known as soft type. The endosperm is all powdery, and the seeds are milky white and lusterless. Can only be used as raw materials for starch, rarely cultivated in China.
5. sweet type also known as sweet corn. The endosperm is mostly horny, containing more sugar, containing starch is low, because of the evaporation of water during maturity so that the surface of the grain wrinkled, translucent. Mostly used as a vegetable, China's planting is not much.
6. sweet powder type, the upper part of the seed for the horny endosperm; the lower part of the powder endosperm. China is rarely cultivated.
7. Waxy type, also known as glutinous type. The endosperm of the seeds is all horny but opaque and waxy, and the endosperm is almost entirely composed of branched-chain starch. Eating properties like glutinous rice, sticky soft and palatable. China only sporadic cultivation.
8. popping type, smaller seeds, rice-shaped or pearl-shaped, endosperm is almost entirely horny, hard and transparent texture, the seed coat is mostly white or red. Especially suitable for processing popcorn and other puffed food. China has sporadic cultivation.
9. lemma type The seed is wrapped by the longer lemma shell, the kernel is hard, difficult to threshing, is a primitive type, no cultivation value.
B. China's national standard for corn quality, according to the grain color and grain quality of corn is divided into five categories:
Yellow corn: the seed coat is yellow, including slightly reddish yellow corn. The U.S. standard states that yellow corn contains no more than 5.0% of other colored corn.
White corn: corn with a white seed coat, including slightly yellowish or pinkish corn. The U.S. standard describes yellowish as light straw colored and states that white corn shall not contain more than 2.0% of other colored corn.
Black Corn: Black corn is a special type of corn whose kernel cuticle deposits melanin to varying degrees and has a dark, shiny appearance.
Glutinous corn: corn rich in viscosity.
Mixed corn: corn mixed with corn other than this category in the above three types of corn more than 5.0%. China's national standard is defined as corn mixed with corn other than this category more than 5.0% of the corn. U.S. standards expressed as the color can neither meet the color requirements of yellow corn, nor meet the color requirements of white corn, and contains white top yellow corn.
Categorized by quality
Conventional corn: the most common and commonly grown corn.
Specialty corn: refers to various types of corn other than conventional corn. The traditional special corn are sweet corn, glutinous corn and popping corn, the newly developed special corn are high quality protein corn (high lysine corn), high oil corn and high straight chain starch corn. Because of special corn than ordinary corn has a higher technical content and greater economic value, foreign countries call them "high value corn".
Sweet corn
Commonly divided into ordinary sweet corn, strengthened sweet corn and super sweet corn. Sweet corn on the production technology and harvesting requirements are more stringent, and short shelf life. China has now mastered a full set of breeding technology and accumulated a number of germplasm resources, domestic breeding of various types of sweet corn can basically meet market demand.
Glutinous corn
Its production technology is much simpler than that of sweet corn, and there are almost no special requirements compared with that of ordinary corn, and the harvesting period is more flexible, and the shelf life is also longer, and there is no need for special storage and processing conditions. Glutinous corn in addition to fresh food, or starch processing industry is an important raw material. China's glutinous corn breeding and production development is very fast.
High oil corn
Higher oil content, especially in which the content of unsaturated fatty acids such as linoleic acid and oleic acid reaches 80%, with a reduction in serum cholesterol, softening the role of blood vessels. In addition, high oil corn than ordinary corn protein is 10-12% higher, lysine is 20% higher, vitamin content is also higher, is grain, feeding, oil, three multi-functional corn.
Quality protein corn (high lysine corn). The yield is not less than ordinary corn, while the whole seed lysine content is 80-100% higher than ordinary corn, in some areas of China, has realized the combination of high yield and high quality.
Purple corn
is a very rare corn varieties, for China's specialties, because the grain is shaped like a pearl, there is a "black pearl". Purple corn quality is excellent and special, but the stick is small, few grains, mu yield is only about 50 kilograms.
Other special corn and variety improvement corn. Including high-starch specialty corn, silage corn, edible corn hybrids.