Rice is one of the staple foods of our daily life, is the seed of rice, rice is what species? Rice in the biological world is the location of: the plant kingdom, angiosperms, Gramineae, Gramineae, rice subfamily, rice genus, Asian cultivated rice. Species in the same genus are not the same species; for example, lions, tigers, and leopards all belong to the genus Panthera, but are not the same species. Species of the genus rice on earth, the total **** there are 18 species, of which 2 have been domesticated by man, namely, Asian cultivated rice and African-type rice, and 17 species are in the native state, for example, Australian rice in northern Australia, broad-leaved rice in the Americas, and wild rice in Asia and so on.
Rice in the southern region of China
The rice that is now commonly consumed by human beings is called Asian cultivated rice, which originated in the Yangtze and Pearl River valleys of China, and as early as in the Neolithic era, rice cultivation in China was widely distributed in the southern region. According to the present archaeological discovery, we can know, China's earliest cultivation of rice in the region is Zhejiang, Jiangsu, Shanghai and so on, then Hubei, Hunan, followed by Yunnan, Guangxi, Guangdong and so on, is a process of advancing from east to west.
Entering the pre-Qin period, China's rice cultivation industry began to experience a south to north promotion process again, as early as in the Western Zhou Dynasty, Spring and Autumn Period, Warring States Period, China's Yellow River Valley has rice cultivation, but the Yellow River Valley planting of rice by the limitations of the water source, when the north of the rice was mainly used for brewing, the northern region's main food crops are corn and millet.
By the Han and Tang dynasties, China's rice cultivation further spread to the Hexi Corridor, Yanshan Mountains, and near the Hetao region. During the Ming and Qing dynasties, rice cultivation was further extended to the northeast, at which time, China's Liaohe River Basin was able to grow rice.
The planting of rice requires a stable water source
Nearly 10,000 years, the earth's climate, as a whole, is tending to dry, cold, China is located in the eastern part of the Eurasian continent, bordering the Pacific Ocean, Asia and Europe is the world's largest continent, the Pacific Ocean is the world's largest ocean, by the difference in the nature of the land and the sea heat, rainfall in our country presents a trend of decreasing from southeast to northwest Decreasing trend, with the climate tends to dry, cold, warm ocean air flow is more and more difficult to y affect the northwest inland, so, since the Southern Song Dynasty, China's Yellow River Basin, water resources are less and less, more and more unfavorable to rice cultivation. However, the northeast is more and more favorable to rice cultivation. Northeast, rainfall is also less, however, the climate is cold, evaporation is also less, therefore, the northeast of the water resources relative to the Yellow River Basin is relatively rich, able to plant rice on a large scale. To grow rice in the Northeast, the first step is to cultivate cold-tolerant varieties.
During the Northern Song Dynasty, the Yellow River Basin had a large number of rice paddies
Why have humans been trying to promote rice? Because rice has a higher yield per unit than wheat, and rice is generally grown where it is suitable for cultivation so that arable land resources can be effectively utilized. There are at least 140,000 species of the rice genus on earth, and in the case of cultivated rice in Asia, people have also bred various varieties. Human cultivation of rice at the same time, rice itself is also in the evolution, therefore, rice varieties are very diverse, some rice can even "return to the ancestors", China's southern region of the paddy field there is a kind of rice, known as "weed rice", weed rice is in fact a cultivated rice The variant of cultivated rice, belonging to a kind of wild rice, weed rice distribution in rice fields, and cultivated rice coexist, which indicates that some rice trying to get rid of human control, to return to the wild state.
Middle and late rice coexist
China's cultivated rice can be divided into indica rice and japonica rice, indica and japonica rice and each has a variant called glutinous rice.
Japonica rice has a long growing period, cold hardy, for the requirements of light conditions are not very strict, therefore, China's northern region of the rice to Japonica rice is dominated by Japonica rice, Japonica rice grains are shorter, showing a rounded shape, with a certain degree of viscosity, China's northern region of the famous rice varieties are all Japonica rice. Japonica rice because of the long growing period, so, can't realize crop rotation with other crops, China's northern region of the rice plantation industry is generally one season a year, rice single yield is low.
Indica rice has a short growth period, heat resistance, can accept a long time of sunshine, therefore, China's southern region is distributed with a large number of indica rice, indica rice grains are longer, viscous and weak, indica rice has a short growth cycle, can be realized with other crops to rotate, so China's southern region of the rice is generally a year of two seasons, and in some cases, and even can be a year of three seasons, the single yield of rice is high.
China's rice cultivation technology has also spread to Japan
Of course, China's southern region is also distributed in the Japonica rice, the Yuan Dynasty, there is "Wuzhong Japonica rice A world" said.
Historical period, China's various places have excellent rice varieties, Hebei, Beijing, Tianjin, Zhejiang, Jiangsu, Shanghai, Anhui, Jiangxi, Hunan, Hubei, Guangdong, Guangxi and other places have excellent rice. But why is northeastern rice very popular now?
China's Yellow River basin due to water resource constraints, many places have been unsuitable for rice cultivation, japonica rice distribution area is concentrated in the northeast, the original world-famous rice varieties, due to water resource constraints, and can not be planted on a large scale. China's Yangtze River Basin and Pearl River Basin, rich in water resources, the distribution of a large number of rice paddies, but, here, the population is large, per capita arable land area is relatively small, the production of excellent varieties, most of them are in the local digestion. China's Northeast, flat terrain, per capita arable land area, suitable for large-scale, commercialized production of excellent varieties of rice.