Rice is a rare earth crop. The higher the temperature, the better the growth momentum and the better the yield. The critical temperature of rice growth is 13, and when it is lower than 13, rice stops growing. In the vegetative growth stage of rice, a leaf grows on average in 5 ~ 7 days, and the effective accumulated temperature of each leaf is 75 ~ 85, which is higher than 13. In the reproductive growth stage of rice, a leaf grows on average in 6 ~ 7 days, and the effective accumulated temperature of each leaf is 130 ~ 145. Now is the period of rice turning green, and it is also the stage of rice vegetative growth. The weather forecast of Heilongjiang province shows that the effective accumulated temperature greater than 13 is 39, which indicates that other farms are hardworking and earn money, and the temperature of 859 farm may be lower. At this time, only when the effective temperature reaches 75 ~ 85 can a leaf grow, 39 leaves. As the saying goes, everything grows on the sun, and rice is no exception. All green plants, such as rice, can give full play to the role of photosynthesis only under the condition of sufficient light, and the nutrients produced by photosynthesis can supply the growth of roots and leaves. Without light, photosynthesis stops, roots and leaves of plants have no nutrient supply, and growth stops.

Rice grows normally under natural light. When the natural light is 50%, rice grows slowly. If the light intensity drops to 5% of the natural light intensity, the growth of rice will stop or even die. All green plants, such as rice, are produced when there is light during the day, which is also a process of making nutrients. The growth of rice needs enough water. When the water supply is insufficient, the physiological function of plants decreases. Especially now is the tillering stage of rice, which is the peak period when rice needs water. So remember, shallow water irrigation can be 3-5 cm in the aquifer now, and it can't drown the rice core.

When to transplant seedlings must be decided according to the age of seedlings and the local safe transplanting time. In principle, we should correctly grasp the farming season and transplant rice seedlings in advance, that is, not later than the safe breeding period. Because, if rice seedlings are transplanted in the early stage of enemy planes, the vegetative growth period can be prolonged, effective tillers can be increased, and low tillers can be competed, so that rice plants can accumulate more substances before ear differentiation, thus planting grass, increasing ears and increasing production. But it should be noted that early transplanting has so many benefits, but we should not be too early. Why is this happening? Transplanting is too early and the temperature is unstable. In cold weather, it is easy to suffer from cold damage or the East China Sea, and it is also easy to suffer from herbicide damage, which leads to delayed seedling growth (Dawan seedling) and the possibility of seedling death. If there are obviously delayed seedlings, the growth period of rice will be delayed, bonsai will be significantly reduced, and the yield will also be significantly reduced.

The transplanting time depends on the age of rice seedlings. According to the characteristics of dry seedlings in cold areas, the seedling age is 35 ~ 40 days, and the seedlings should be transplanted from 3-leaf 1 core stage to 3.5-leaf stage. Determine the transplant time according to the local safe transplant time. The transplanting time of dry seedlings in Heilongjiang Province is 13. When the local temperature reaches 14, transplanting should be started. Transferred to temperate zone, May will be the high-yield transplanting period of 10 ~ 20. In the private temperate zone, the middle and late May and May 15 ~ 25 are the high-yield transplanting periods. Due to the delay of transplanting time, the yield is obviously reduced.