Rice in South China
Nowadays, rice widely eaten by human beings is called Asian cultivated rice, which is native to the Yangtze River basin and the Pearl River basin in China. As early as the Neolithic Age, rice cultivation was widely distributed in southern China. According to archaeological findings, we can know that the earliest rice planting areas in China are Zhejiang, Jiangsu and Shanghai, then Hubei and Hunan, and then Yunnan, Guangxi and Guangdong, which is a process from east to west.
In the pre-Qin period, rice planting in China began to experience a process of popularization from south to north. As early as the Western Zhou Dynasty, the Spring and Autumn Period and the Warring States Period, rice was planted in the Yellow River Basin of China. However, rice cultivation in the Yellow River basin is limited by water sources. At that time, rice in the north was mainly used for wine making, and the main food crops in the north were millet and millet.
During the Han and Tang Dynasties, rice cultivation in China was further extended to Hexi Corridor, Yanshan Mountains and Hetao area. During the Ming and Qing Dynasties, rice cultivation was further extended to the northeast of China. At this time, rice can be planted in the Liaohe River Basin of China.
Growing rice requires a stable water source.
In recent10 million years, the climate on the earth tends to be dry and cold as a whole. China is located in the east of Eurasia, which is the largest continent in the world, and the Pacific Ocean is the largest ocean in the world. Due to the difference of thermal properties between land and sea, the rainfall in China tends to decrease from southeast to northwest. As the climate tends to be dry and cold, it is increasingly difficult for warm ocean air to deeply affect it. However, the northeast region is increasingly conducive to rice cultivation. There is less rainfall in Northeast China, but the climate is cold and evaporation is less. Therefore, compared with the Yellow River basin, the northeast is relatively rich in water resources and can grow rice in a large area. To plant rice in the northeast, we must first cultivate cold-resistant varieties.
During the Northern Song Dynasty, there were a large number of rice fields in the Yellow River basin.
Why has mankind been trying to promote rice? Because the yield of rice is higher than that of wheat, it is necessary to plant rice where it is suitable, so as to make effective use of cultivated land resources. There are at least 6,543,800+400,000 species of Oryza on the earth. As far as cultivated rice in Asia is concerned, people have also cultivated various varieties. While human beings are cultivating rice, rice itself is also evolving. Therefore, there are many varieties of rice, and some varieties can even "return to their ancestors". There is a kind of rice called "weedy rice" in the paddy fields in southern China. Weedy rice is actually a variety of cultivated rice and belongs to a kind of wild rice. Weedy rice is distributed in paddy fields and coexists with cultivated rice, indicating that some rice are trying to get rid of human control and return to the wild state.
Mid-season and late-season rice coexist.
Cultivated rice in China can be divided into indica rice and japonica rice, each of which has a variety called glutinous rice.
Japonica rice has a long growth period, is cold-resistant, and is not very strict with light conditions. Therefore, japonica rice is the main rice in northern China, and its rice grains are short, round and sticky. The famous rice variety in northern China is japonica rice. Japonica rice has a long growth period and cannot rotate with other crops. Rice planting in northern China is generally one season a year, and the yield of rice is low.
Indica rice has a short growth period, is heat-resistant and can receive sunlight for a long time. Therefore, there are a large number of indica rice in southern China. Indica rice has long seeds, weak viscosity and short growth cycle, which can be rotated with other crops. Therefore, rice in southern China is usually harvested twice a year, and in some places, it can even be harvested three times a year, with high yield of single-season rice.
China's rice planting technology has also spread to Japan.
Of course, japonica rice is also distributed in the south of China, and it was said in the Yuan Dynasty that "Wuzhong japonica rice is the best in the world".
In the historical period, there were excellent rice varieties all over China, such as Hebei, Beijing, Tianjin, Zhejiang, Jiangsu, Shanghai, Anhui, Jiangxi, Hunan, Hubei, Guangdong and Guangxi. But why is northeast rice so popular now?
Due to the limitation of water resources in the Yellow River basin in China, many places are no longer suitable for rice cultivation. The distribution area of japonica rice is concentrated in the northeast, and the once famous rice variety cannot be planted on a large scale due to the limitation of water resources. China's Yangtze River basin and Pearl River basin are rich in water resources and have a large number of paddy fields. However, the population is large, the per capita arable land area is small, and most of the excellent varieties produced are digested by the local people. Northeast China has a flat terrain and a large area of cultivated land per capita, which is suitable for large-scale and commercial production of improved rice varieties.