Rice, an annual gramineous plant, is about 65438 0.2 meters high, with long flat leaves and panicles composed of many spikelets. The fruit is rice, which is called rice or rice after hulling. Nearly half of the world's population, rice can be divided into indica and japonica rice, early rice and mid-late rice, glutinous rice and non-glutinous rice. Rice grains produced by rice are called rice or rice after hulling. Besides being edible, rice can also be used as an industrial raw material for brewing wine and sugar, and rice husk and straw also have many uses. Rice belongs to Gramineae and is an extremely old crop. According to archaeological findings, rice has been cultivated in China for at least 7000 years. There are two kinds of cultivated rice in the world, Asian cultivated rice and African cultivated rice. Among them, Asian cultivated rice has a large planting area and is spread all over the world, so it is called common cultivated rice. A large number of facts have proved that the south of China is at least one of the origin centers of common cultivated rice. Rice has been differentiated after long-term evolution and remolding under different ecological conditions. Ding Ying (1957), a scholar in China, concluded that cultivated rice in China can be divided into two subspecies, indica and japonica, and can be divided into early, late and late rice under indica and japonica according to the temperature and light response, water requirement and endosperm starch characteristics of the variety. So strictly speaking, it is not accurate to classify indica rice, japonica rice and glutinous rice side by side. In fact, indica rice and japonica rice are divided into waxy and waxy, as shown in the following figure: waxy-long-grain waxy (small waxy) indica rice is non-waxy-glazed rice is waxy-poly-waxy (big waxy) japonica rice is non-waxy-japonica rice is similar to its ancestor wild rice. Indica rice is suitable for planting in low latitude and low altitude hot and humid areas.