Is rice planted on the roof?

Generally, rice is not planted on the roof, which is not suitable, practical and economical.

Rice refers to the seeds without rice husk removed, which belongs to the common rice subspecies in the subgenus of Gramineae common cultivated rice in botany. Humans have identified 22 kinds of rice, but the only one used for bulk trade is ordinary rice.

China is one of the countries with the longest history of rice cultivation and the richest rice genetic resources. The ancient cultivated rice specimens unearthed from Yuchanyan site in Shouyan Town, Dao County, Hunan Province, confirm that China has been cultivated for more than 6.5438+0.4 million years, and it is the known origin of cultivated rice in the world.

distribution range

(1) Rice is widely distributed in China. Rice is widely distributed in China, spanning five temperate zones: tropical zone, subtropical zone, warm temperate zone, middle temperate zone and cold temperate zone. Generally speaking, due to the influence of latitude, temperature, monsoon, rainfall, altitude, topography and other factors, the distribution of rice planting areas in China is concentrated in the southeast, scattered in the northwest, vertical in the southwest and gradually decreasing from south to north.

(2) Rice planting areas are mainly in the south. Rice planting areas are mainly in the south, and the three major rice planting areas in the south account for 93.6% of the total sown area in China. There are obvious regional differences in rice planting areas, which can be divided into 9 sub-regions, of which the rice planting area in the Yangtze River basin has accounted for 65.7% of the country. The three major rice-growing areas in the north account for about 6% of the national sown area, and their rice-growing areas span a lot, including seven obviously different rice-growing subregions.

(3) Most southern provinces are double-cropping rice, mainly planting hybrid indica rice and conventional rice, while most northern rice areas are single-cropping rice, mainly planting japonica rice.

(4) Provinces with large rice planting area and yield account for about 85% of the whole country. Hunan, Jiangxi, Guangxi, Guangdong, Sichuan, Anhui, Jiangsu, Hubei, Zhejiang, Fujian, Yunnan, Heilongjiang and other provinces (regions) with large rice planting area and output have 12, accounting for about 85% of the country.

(5) In terms of varieties:

① Indica rice. Indica rice is mainly distributed in 16 southern provinces (cities, districts), namely Hainan, Guangdong, Guangxi, Hunan, Hubei, Yunnan, Guizhou, Sichuan, Chongqing, Fujian, Jiangxi, Zhejiang, Jiangsu, Anhui, Shaanxi and Henan. Sichuan, Chongqing, Jiangxi, Guangxi, Guangdong, Fujian and Hainan are basically indica rice. By region, more than 87% of rice in Hubei, more than 70% in Anhui, more than 92% in Guizhou and more than 75% in Henan are indica rice, about 65% in Zhejiang, 32% in Yunnan and 0/7% in Jiangsu/KLOC.

② Japonica rice. There are mainly three japonica rice distribution areas: the northern japonica rice area north of Jianghuai, the southern japonica rice area with Jiangsu Province as the core and the Yunnan-Guizhou Plateau japonica rice area with Yunnan Province as the core. The average annual output of commercial japonica rice in China is over 8 million tons, of which Heilongjiang Province accounts for about 60%. There are 24 japonica rice producing provinces, mainly three northeastern provinces and four provinces of Jiangsu, Zhejiang, Anhui and Yunnan. The sown area and yield of japonica rice in these seven provinces account for about 85% of the sown area and yield of japonica rice in China. The three northeastern provinces are the main provinces that can sell commercial japonica rice outside the province, and Jiangsu and Anhui also sell a small amount of commercial japonica rice outside the province.

③ Early (indica rice). Early indica rice planting areas are distributed in Hainan, Guangdong, Guangxi, Fujian, Jiangxi, Hunan, Hubei, Anhui, Zhejiang, Yunnan, Sichuan, Guizhou and Chongqing 13 provinces. Hunan, Hubei, Jiangxi, Guangdong, Anhui, Zhejiang, Guangxi and Fujian are the main early indica rice producing provinces in China, with Hunan, Guangxi and Jiangxi as the main ones.

Since the 1990s, with the continuous advancement of China's market economy construction, industries in various places have developed rapidly, especially in the southern coastal areas, the cultivated land area has been greatly reduced, and the sown area of early rice has dropped significantly. In recent 20 years, the planting area and yield of early indica rice decreased by 40.9% and 39.8% respectively, especially in Zhejiang, Guangdong and Fujian. Compared with 1984 in 2004, Zhejiang Province has reduced100000 mu; Guangdong province reduced130,000 mu or more; Fujian province has reduced more than 3 million mu. In recent two years, with the encouragement of national policies, China's early rice planting area has recovered, especially in several traditional agricultural provinces such as Jiangxi and Hunan.

④ Mid-season rice and one-season rice. Mid-season rice and one-season rice production are distributed all over the country except Guangdong, Hainan and Qingdao, among which eight provinces (cities) such as Sichuan, Jiangsu, Heilongjiang, Anhui, Hubei, Yunnan, Hunan and Chongqing account for more than 70% of the country's sown area.

⑤ Late rice. Late rice production is distributed in southern 15 provinces, which is similar to early rice.