Rice is divided into indica rice and japonica rice, early rice and mid-late rice, glutinous rice and non-glutinous rice according to the type of rice. It can be divided into conventional rice and hybrid rice according to the way of planting. There are other classifications, which can be divided into paddy rice and floating rice according to soilless cultivation or not; According to the life cycle, it can be divided into seasonal rice and "lazy rice" (over-year ratooning rice); According to height, it can be divided into ordinary rice and giant rice of about 2 meters; According to salt and alkali tolerance, it can be divided into ordinary freshwater rice and "sea water rice".

In rice, seeds are usually germinated to produce new seeds, which is a growth cycle of rice, that is, the growth period. The growth period can be divided into seedling stage, turning green stage, tillering stage, long spike stage (spike differentiation stage) and seed setting stage.

Seedling stage: including germination, germination and trefoil stage.

Greening period: the buffer period for rice survival from seedling field to Honda after transplanting.

Tillering stage: including initial stage, peak stage, final stage (highest tillering stage) and effective tillering termination stage which determines the key period of spike number.

Long ear stage: including ear differentiation stage, jointing stage and booting stage when the sheath of flag leaf bulges.

Seed setting stage: including heading and flowering stage, milk maturity stage, wax maturity stage, yellow maturity stage and full maturity stage.