In daily life, rice, soybeans, wheat, and corn are all major crops in our country. They are indispensable foods in our daily diet and play an important role in our daily lives. So does anyone know which of rice, wheat, corn, and soybeans was first cultivated by the Chinese?

Rice: It is currently one of the staple foods of half of the world's population. In addition to daily rice consumption, it can also be used for brewing and sugar making as industrial raw materials. Rice husks and rice stalks can be used as livestock feed.

Corn: Native to Central and South America, my country's main producing areas are in the mountainous areas of Northeast China and Southwest China.

Soybean: Most commonly used to make various soy products, extract soybean oil, brew soy sauce and extract protein. Soybean has a history of 5,000 years of cultivation in China and is one of the important food crops.

Wheat: It belongs to the Gramineae family. The Mesopotamia is the first region in the world to start growing wheat.

Among rice, wheat, corn, and soybeans, rice was the first cultivated by the Chinese. Rice began to appear in the Yangtze River basin of China as early as seven thousand years ago.

Crops are green plants cultivated by humans, called crops, and crops with larger cultivated areas in farmland are called crops. At present, there are about 1,500 kinds of plants cultivated by humans, which can be roughly divided into three categories: agricultural crops, horticultural crops and forest trees.

Basis and method of crop classification:

1. Classification according to crop physiological and ecological characteristics

1. Divided according to the requirements of crops for temperature conditions

Temperature-loving crops: The temperature and accumulated temperature required during the whole growth period are both high, and the minimum temperature for growth and development is 10℃, such as rice, corn, cotton, sorghum, millet, peanuts, tobacco, sugarcane, sesame, jute, kenaf Wait;

Hardy crops: The temperature and accumulated temperature required during the whole growth period are relatively low, and the minimum temperature for growth and development is about 1-5°C, such as wheat, barley, rye, oats, rape, broad beans, vetch, etc.

2. Divided by crop response to photoperiod

Long-day crops: All crops that are suitable for growth and development under long-light conditions and can promote development by prolonging the light are called long-day crops, such as wheat, barley, rye, rape, etc.

Short-day crops: crops that are suitable for growth and development under long dark conditions and can promote growth by extending the dark time are called short-day crops, such as rice, corn, cotton, sorghum, peanuts, soybeans, tobacco, jute, raw hemp Wait.

Neutral crops: There are no strict requirements on the length of light, such as peas, buckwheat, etc., which are called neutral crops.

Constant day crops: The length of sunshine must be controlled within a certain period of time to complete its growth cycle. For example, some varieties of sugarcane can only bloom when the sunshine length is 12 hours and 45 minutes.

3. Divided according to the characteristics of the ways of assimilation of carbon dioxide by crops

Three-carbon (C3) crops: The carbon dioxide compensation point for photosynthesis is high, and there is strong photorespiration, such as rice, wheat, cotton, soybean, tobacco, etc.

Four-carbon (C4) crops: The carbon dioxide compensation point for photosynthesis is low. Under high temperature and strong light, the photosynthetic intensity is higher than that of three-carbon crops, such as corn, sorghum, and sugarcane.

Crassulaceae (CAM) crops: The stomata open at night to absorb carbon dioxide and store it in the plant. The white weather pores are closed. The carbon dioxide in the plant is used for photosynthesis. The plants include sedum, sisal, pineapple, orchid, etc.

2. Classification according to the characteristics of agricultural production

1. Division of planting period: spring planting crops, summer planting crops, autumn planting crops, winter planting crops;

2. The division of planting density: dense planting crops, row crops;

3. Division of harvest season: summer crops and autumn crops;

4. Stalk height division: tall crops, short crops, creeping crops

5. Classification of root growth characteristics: tap root crops, fibrous root crops, and root crops

3. Divided by the combination of usage and botany system

1. Food crops

Cereals: barley, wheat, rice, corn, sorghum, rice, chestnut

Bean crops: soybeans, mung beans, peas, broad beans

Tuber crops: sweet potato, potato, taro

2. Cash crops

Fiber crops: cotton, kenaf, ramie

Oil crops: rape, peanut, sunflower, sesame

Sugar crops: sugar cane, sugar beet

Favorite crops: tobacco, coffee, tea

3. Feed and green manure crops

Leguminous: vetch, alfalfa, astragalus, etc.;

Gramineae: Sudan grass, ryegrass, brome grass, etc.,

Others: Azolla, water hyacinth, water lotus, water peanut, etc.

4. Special use

Mainly include: reed, mat grass, mint, spearmint, mulberry, rubber, pepper, star anise, cinnamon and so on.