Indica rice and japonica rice are two subspecies of cultivated rice in Asia, and they are quite different in morphological characteristics, physiological functions and cultivation characteristics.

In terms of morphological characteristics and economic characters, generally, the tillering ability of indica rice is stronger, the first panicle node is shorter, the leaf color is lighter, there are more hairs on the leaves, the grain is slender, the barnyard grass is short, hard and straight, the shell color is green and white when heading, and it is easy to thresh, and the amylose content of indica rice is generally higher, and the cooking swelling is high and the viscosity is low. Generally speaking, japonica rice in tillering ability is not as good as indica rice. The first panicle is longer, the leaves are darker, the leaves are not hairy, the grains are short and round (a few japonica rice varieties also have long grain shapes), the barnyard grass is long, messy and soft, and the shell color is green when heading, so it is not easy to thresh. The amylose content of japonica rice is low, and the rice is sticky and swollen.

from the physiological characteristics and adaptability, indica rice generally has strong fertilizer absorption and poor cold tolerance, and can germinate only when the average daily temperature is above 12℃, so indica rice has good adaptability. Japonica rice has strong fertilizer tolerance but poor fertilizer absorption, strong cold tolerance, and can germinate when the average daily temperature reaches 1℃, so its adaptability is poor. Under the suitable temperature, the photosynthetic rate of indica rice leaves is higher than that of japonica rice, with good luxuriance and easy to grow early and develop quickly.

geographically, indica rice is suitable for planting in hot and humid areas with low latitude and low altitude, such as the south of China. Japonica rice is suitable for planting in high latitude and high altitude areas, such as northeast rice areas, north rice areas and northwest rice areas in China, as well as high altitude rice areas in Yunnan-Guizhou Plateau and mixed cropping areas of single-season rice and double-season rice in the middle and lower reaches of the Yangtze River.