What are the main crops that farmers choose to plant in the middle and lower reaches of the Yangtze River? Please provide a justification for the answer.

The plain area in the middle and lower reaches of the Yangtze River belongs to a typical subtropical monsoon climate, which is warm and humid. The frost-free period is 265,438+00 ~ 280 days, the accumulated temperature is ≥ 65,438+00℃, and the annual precipitation is 800 ~ 65,438+0,600 mm. It has a tradition of intensive cultivation and a vast water area. It mainly grows rice and also produces cotton, hemp, rape, silk and tea. To the north of the Yangtze River, the double cropping system of rice and wheat is practiced between Jianghuai and Jianghuai, while the triple cropping system of green manure-rice-rice, rape-rice or wheat-rice-rice prevails in the south of the Yangtze River, making it one of the regions with the highest level of intensive planting in the world. The altitude in northwest China is generally as high as 500 ~ 3000 meters, and the climate is cool and dry. Frost-free period 100 ~ 220 days, accumulated temperature ≥ 10℃, annual precipitation in agricultural areas is about 250 ~ 600 mm, mainly planting cold-loving spring wheat, winter wheat, corn, potato and naked oats; It is usually cooked once a year, and there is a small amount of leisure space all year round. Xinjiang, Hexi Corridor, Yinchuan Plain and Hetao Irrigation Area are mainly irrigated agriculture, planting wheat, corn, rice and a small amount of cotton and sugar beet; The climate in southern Xinjiang is warm, and more crops are harvested twice a year.

Rice: a plain with natural cold and warm, good water conditions and good light and heat.

The plain in the middle and lower reaches of the Yangtze River is one of the three major plains in China. Located along the middle and lower reaches of the Yangtze River east of Yichang, Hubei, it consists of two lakes (Jianghan Plain in Hubei and Dongting Lake Plain in Hunan), Poyang Lake Plain, Jiangsu-Anhui Plain along the Yangtze River, He Lixia Plain and Yangtze River Delta Plain, covering an area of about 200,000 square kilometers. The two lakes plain is bounded by Jingjiang River, which is called Jianghan Plain in the north and Dongting Lake Plain in the south. Jianghan Plain is mainly formed by alluvial deposits of the Yangtze River and the Han River. Since the entrance of Jingjiang North dike into Jianghan Plain was completely blocked around 1300, the sediment carried by Hanjiang River has played a major role in the development of Jianghan Plain, and its delta has become an important part of Jianghan Plain. The terrain of the Hanjiang River Delta is also slightly inclined from northwest to southeast, and there are many lakes in the southeast front. Dongting Lake Plain is mainly formed by the Yangtze River sediment from the south bank of Jingjiang River passing through Taiping, Ouchi, Songzi and Tiao County (blocked at 1958). The area is about 1 1,000 square kilometers. Most of them are below 50 meters above sea level, high in the north and low in the south, with dense water networks and fertile soil. The flood plain in the middle of Poyang Lake Plain, except the red mounds at the edge, is mainly formed by the scouring and silting of rivers such as Jiangxi, Fuzhou, Xinjiang, Poyang Lake and Xiushan, among which Ganjiang is the main one. It covers an area of about 20,000 square kilometers. The terrain is low and flat, most of which are below 50 meters above sea level. The water network is dense, and the surface is covered with red soil and river alluvium. The plain along the Yangtze River in Jiangsu and Anhui mainly refers to the long and narrow alluvial plain distributed along the banks of the Yangtze River between Hukou and Zhenjiang, including Wuhu Plain and Chaohu Plain. The width and width of the plain alternate, the river flows in and out, and the velocity is gentle; Since Datong, every time supported by the tide, the flow velocity has slowed down and the sediment deposition has been strengthened. Especially when the river passes through the rock head forced by the rock mound, river branches and sandbars appear between the branches. There are many lakes on both sides of this river. The Yangtze River Delta is developed from the estuary below Zhenjiang. To the north of the delta is the He Lixia Plain. The plain is a dish-shaped depression with high, middle and low levels in the Zhou Dynasty. The northern edge of the depression is the old course of the Yellow River; The southern margin is the delta on the north bank of the Yangtze River; The west edge is Hongze Lake and Yunxi levee; The eastern edge is the coastal plain of northern Jiangsu.

The banded plain in the middle and lower reaches east of the Three Gorges of the Yangtze River in China. Huaiyang Mountain and Huanghuai Plain are in the north, and Jiangnan hills and Zhejiang and Fujian hills are in the south. It is alluvial from the Yangtze River and its tributaries. It covers an area of about 200,000 square kilometers. The terrain is low and flat, and the altitude is mostly about 50 meters. The middle reaches include Jianghan Plain in Hubei, Dongting Lake Plain in Hunan and Poyang Lake Plain in Jiangxi. The downstream plains include the plain along the Yangtze River and Chaohu Lake in Anhui Province (the central plain of Anhui Province), and the Yangtze River Delta between Jiangsu, Zhejiang and Shanghai. Most of the climate belongs to the north subtropical zone, and a small part belongs to the northern edge of the middle subtropical zone. The annual average temperature is 14 ~ 18℃, the most Leng Yue average temperature is 0 ~ 5.5℃, the absolute minimum temperature is-10 ~-20℃, the hottest month average temperature is 27 ~ 28℃, and the frost-free period is 2 10 ~ 270 days. For agricultural crops, the annual precipitation is 1000 ~ 1400 mm, which is concentrated in spring and summer. Zonal soil is only found in low hills and gentle hills, mainly yellow brown soil or yellow cinnamon soil. The southern margin is red soil, and most of the plains are paddy soil. With developed agriculture and high land reclamation index (62. 1% in Shanghai and 45.6% in Jiangsu), it is an important grain, cotton and oil production base. Rich in rice, wheat, cotton, rape, silkworm, ramie, jute and so on. Rivers and branches crisscross, and lakes are dotted. The lake covers an area of 20,000 square kilometers, equivalent to 10% of the plain area. Large lakes, including small lakes, have an area of10.3 million square kilometers, accounting for more than 20% of the plain area of the two lakes, which is the place with the largest number of lakes in China. There are many freshwater lakes such as Poyang Lake, Dongting Lake, Taihu Lake, Hongze Lake and Chaohu Lake, which are connected with the Yangtze River and have the functions of regulating water volume and reducing flood peak. They produce fish, shrimp, crab, lotus, water chestnut and reed, as well as world treasures such as Chinese sturgeon, Chinese alligator and baiji. Aquatic products occupy an important position in China and are known as the land of plenty. It is one of the most economically developed areas, including Shanghai, Nanjing, Wuhan, Nanchang, Suzhou, Wuxi, Changzhou, Nantong, Wuhu and Changsha. The main industries are steel, machinery, electricity, textiles and chemistry, and it is an important industrial base. The plain is located in the hub of China's north-south and east-west transportation networks, with developed land and water transportation. The Yangtze River runs through the middle and becomes an east-west waterway artery, and its many tributaries form a huge waterway network.

Abundant water, long flood season and small seasonal variation of water level; The river has a large drop and abundant water power; River sediment concentration is small; Ice-free period

The high temperature period is consistent with the rainy season, with abundant water and heat resources and good coordination. Plum rains are timely and suitable, which is beneficial to rice growth. The plain in the middle and lower reaches of the Yangtze River and the Pearl River Delta have low terrain, fertile soil and convenient irrigation. Agricultural production in the Yangtze River basin has a long history and a high level of production.