The main varieties of rice

Since rice is the main food crop of mankind, it is known that there may be more than 140,000 varieties of rice in the world, and scientists are still researching and developing new varieties of rice, so it is difficult to estimate how many varieties of rice there are. There is a classification of African rice and Asian rice, but a simpler classification is based on the starch content of the rice grain. Rice starch is divided into straight chain and branched chain two kinds. The more branched starch there is, the more viscous the rice will be when cooked. Indica rice: About 20% is straight-chain starch. It is medium viscous. Indica rice originated in subtropical, planted in tropical and subtropical areas, short growing period, in the place of long frost-free period can be ripe many times a year. After shelling to become indica rice, the appearance of slender, low transparency. Some varieties have a reddish skin, such as the red rice produced in Jiangxi, China, and the rice is drier and looser after cooking. It is usually used for turnip cakes, rice noodles and fried rice.

Japonica rice: Japonica rice has less straight-chain starch, less than 15 percent. It is grown in temperate and frigid regions, with a long growing period, and generally matures only once a year. After hulling to become Japonica rice, the appearance is short, round and transparent (some varieties of rice grains have localized white powdery texture). Cooking characteristics between glutinous rice and indica rice. Use for general food rice.

Indica and japonica rice is a long-term adaptation to different ecological conditions, especially temperature conditions and the formation of the two climatic ecotypes, the two in the morphology and physiological characteristics of the Department of obvious differences. In the world rice-producing countries, only China is indica japonica rice coexistence, and the area are very large, the geographical distribution is obvious. Indica rice is mainly concentrated in the tropical and subtropical lowlands south of the Huaihe River in South China, the distribution range is narrower than japonica rice. Indica rice has a heat-resistant, light-resistant habit, its botanical characteristics for the grain shape is long and thin, poor viscosity, leaf blade rough and hairy, velvet hairs on the husk is sparse and short as well as easy to drop the grain, etc., are similar to the wild rice, therefore, indica rice is the evolution of cultivated rice from the wild rice, is the basic type. Japonica rice is widely distributed, from the southern alpine mountains, Yunnan-Guizhou Plateau to the Qinling Mountains, north of the Huaihe River in the vast area are cultivated. Japonica rice has a cold-resistant, low-light habits, grain shape short round, rice viscous stronger, less hairy or hairless leaf surface, glumes long dense, not easy to drop grain and other characteristics, and wild rice has a big difference. Therefore, it can be said that japonica rice is human will indica rice from the south to the north, from low to high after the introduction of seeds, and gradually adapted to the low temperature of the variant. Glutinous rice: the content of medium branched-chain starch is close to 100%, the viscosity is the highest, and is divided into Japonica glutinous and indica glutinous. Japonica glutinous appearance round and short, indica glutinous appearance slender, color are white opaque, cooked rice is softer, sticky. Usually, Japonica glutinous rice is used for brewing and rice cake, and Indica glutinous rice is used for congee and rice dumplings.

China do staple food for non-glutinous rice, do pastry or brewing for glutinous rice, the two main difference in the viscosity of the grains of rice, glutinous rice viscous, non-glutinous rice viscous weak. Stickiness is mainly determined by the structure of starch, glutinous rice starch structure to branched-chain starch-based, non-glutinous rice contains more straight-chain starch. When the starch is dissolved in iodine solution, out of non-glutinous rice iodine absorption, the starch becomes blue, while glutinous rice iodine absorption is small, the starch is brownish red. Generally glutinous rice cold and drought tolerance are stronger than non-glutinous rice.

In addition, in rice taxonomy, according to the rice cultivation method and the amount of water required during the growing period, there are water rice and dry rice. Dry rice, also known as land rice, is planted in the drylands by rain-fed or only supplemented by a small amount of irrigation of the rice crop, the lifetime irrigation water is only 1/4 ~ 1/10 of rice, suitable for low-lying flood-prone drylands, rainfall more mountainous areas and insufficient water or energy-scarce rice area planting. To understand rice, the most basic division, often first according to the conditions required for the growth of rice, that is, water irrigation to distinguish, so rice can be divided into water rice and dry rice. However, most of the organizations that study rice cultivation focus on water rice, and a smaller percentage on dry rice.

Dry rice can also be called land rice, it and the main varieties of rice is actually similar, the same indica, japonica two subspecies. Some rice can be planted directly in the dry land (but the yield is less), can also be planted in the paddy field. Dry rice, on the other hand, is highly drought-resistant and can produce spikes on barren land even if there is a lack of water for irrigation. Dry rice is grown in mountainous areas where rainfall is scarce, and many special mountain rice varieties have evolved depending on the region. Dry rice has become an important research area for artificial hybrid rice, which can help farmers save water for irrigation.

One theory is that the earliest dry rice may have been Champa rice. Chinese ancient history of the Song Dynasty "food and goods," has recorded, "sent to Fujian to take Chancheng rice 30,000 dendrobiums, distributed to the three ways for the seed, choose the people's field of high up the dill, cover the dry rice is also ...... rice than China's long spikes without awns, the grain difference between the small, do not choose the ground to live." However, there is still controversy, the reason is that scholars suspect that in terms of regional climate, Chamchung rice is likely to be a dry species of rice, rather than the earliest dry rice. Speaking of artificial rice, in 1973, Yuan Longping was known as the father of hybrid rice after he successfully used scientific methods to produce the world's first hybrid rice. After four years of research, he led his team to explore from hundreds of rice species in the world and had his own insights on self-pollination of rice species. Yuan Longping believes that wild rice is not necessarily all self-pollinating, he found a wild rice called "wild defeat" in Hainan Island, and successfully with the existing rice with a number of combinations of rice varieties. These combinations could not be self-pollinated, but relied on the stamens of a side plant for pollination, but the yield was double that of the original rice. However, in the first few years, although the new rice cultivated increased in rice volume, and most of them did not have pollen, which meets the requirements of the new variety, but some of them did have pollen, and could produce the next generation, and the amount of rice was not abundant; but Yuan did not give up, and until the ninth year, tens of thousands of plants of the new rice did not have pollen, and reached the requirements of the new variety, that is, Yuan's three-lines method of hybridized rice.

See also: hybrid rice, super hybrid rice