Key Points of Water Management at Different Growth Stages of Rice

Rice has relatively strict requirements for water conditions, and the water demand varies at different growth stages. To ensure stable and high yields of rice, scientific water management should be carried out according to the different growth stages. 1. Shallow water and frequent irrigation at the tillering stage.

Shallow water and frequent irrigation at the tillering stage allows good light penetration to the base of the rice plants, so that sunlight can shine directly on the stems of the rice plants, raising the water temperature and soil temperature, increasing oxygen in the soil, promoting root development, improving fertilizer uptake capacity, promoting early tillering, and increasing the rate of tillers forming panicles. The depth of irrigation water should be based on weather conditions, generally 3-5 cm, and a shallow water layer should be used on cloudy and rainy days. Slightly deeper water is preferable in hot and dry weather.

2. Drainage and field drying at the sufficient seedling stage.

In the late tillering stage, when the total number of tillers per mu of rice reaches 200,000-230,000, the field should be drained and dried to control ineffective tillering, which is beneficial for the main stem and large tillers to grow well and quickly, achieving the goal of more panicles, larger panicles, full grains, and high 1000-grain weight. Field drying should take weather characteristics into account. In mostly rainy weather, field drying is difficult, so the drying time can be longer, and it is necessary to seize sunny days to dry the field early, or take advantage of intermittent sunny days to dry the field. In dry weather, places with poor water conservancy conditions can lightly dry the field or skip field drying.

3. Shallow water and regular irrigation at the young panicle differentiation stage.

At the young panicle differentiation stage, if water is insufficient, the number of spikelets will be reduced, causing degeneration of glumous flowers and a decrease in the number of grains per panicle; if irrigation water is too deep, the stems of the plants will become soft and lodging is likely to occur. Generally, maintaining a water layer of 6-8 cm is appropriate. In dry weather, the water layer can be slightly deeper. In fields with mostly rainy weather, a relatively high groundwater level, or rice seedlings showing delayed senescence, moist irrigation can be adopted, keeping the soil alternating between dry and wet. The young panicle differentiation stage is not tolerant of low temperatures. When stronger cold air occurs, deep water should be irrigated to maintain a certain deep water layer, so as to stabilize soil temperature and avoid the impact of low temperature on young panicle development. In case of floods, drainage should be carried out promptly, and while draining, the seedlings should be washed to remove mud from the rice leaves.

4. Maintain a water layer at the heading and flowering stage.

At the heading and flowering stage, a certain water layer should be properly maintained to regulate soil temperature, increase air humidity between plants, and promote full heading of rice; in low-temperature weather, deep water should be irrigated to keep warm.

5. Alternating dry and wet at the grain-filling and milk-ripening stage

The grain-filling and milk-ripening stage is an important period for grain plumpness. If drought and water shortage occur, it will cause premature aging of leaves and affect grain plumpness; if a deep water layer is maintained, it will affect root activity in the later stage, resulting in poor grain filling. Therefore, during the grain-filling and milk-ripening stage, it is appropriate to keep the soil moist, so that irrigation does not lead to water accumulation, and water cutoff does not lead to water shortage, alternating dry and wet, so as to facilitate full grains. After the yellow-ripening stage, the water requirement decreases. At this stage, water accumulation in the field must be avoided to promote maturity and facilitate harvesting.