Rice field management techniques during high temperatures and technical recommendations for defending against high temperatures in the Yangtze River Basin

Currently, it is the jointing stage of rice, and when encountering high-temperature weather, rice will inevitably develop various diseases. Therefore, to achieve high rice yields, field management techniques are still needed. So how should rice in the Yangtze River Basin region be managed in the field?

Currently, single-season middle indica rice in the middle and lower reaches of the Yangtze River is successively entering the jointing stage, some single-season middle indica rice on rapeseed stubble and early stubble has already reached the jointing-booting stage, single-season japonica rice is at the tillering stage, and double-season late rice is at the seedling-raising stage; single-season middle indica rice at higher altitudes in the southwest region is at the booting stage to initial heading stage, while single-season middle indica rice at lower altitudes is successively entering the flowering and grain-filling stage. According to forecasts from the Central Meteorological Observatory, over the next 10 days, the Jianghuai, Jianghan, Jiangnan, and eastern Sichuan Basin regions will experience high-temperature weather processes lasting 4—7 days with temperatures of 35—37℃, and maximum temperatures in some areas may reach 38—40℃. In response to the current climate and rice growth characteristics, the Rice Expert Steering Group of the Ministry of Agriculture and Rural Affairs, together with the National Agricultural Technology Extension Service Center, has proposed technical recommendations for field management to defend against high temperatures in rice in the Yangtze River Basin.

1. Regulate temperature with water to defend against high-temperature heat damage

For single-season middle rice from the tillering to jointing stage, it is necessary to leverage the plant's own transpiration-based physiological cooling capacity and implement intermittent moist irrigation with a 2—4 cm water layer and alternating wet and dry conditions; for single-season middle rice from the booting to flowering stage, if continuous high-temperature weather above 35℃ occurs, an 8—10 cm water layer should be maintained in the field to lower canopy and leaf temperatures, and if necessary, clear water can be sprayed around midday to cool the plants; for drought-affected areas, water should be actively diverted and replenished in a timely manner to improve irrigation efficiency and promote rice growth and development; for double-season late rice seedling fields, water management should be strengthened, and where conditions permit, daytime irrigation and nighttime drainage can be adopted to accelerate water circulation, regulate temperature, promote robust seedling growth, and ensure water for transplanting.

2. Apply panicle fertilizer well to enhance plant resistance

For fields with an appropriate number of population stems and tillers and normal leaf color, apply panicle fertilizer in two applications at the 4th and 3rd leaf from the top stages; the nitrogen application rate should be 40%—50% of the total nitrogen application for japonica varieties and 30%—40% for indica varieties; for fields with a relatively small number of population stems and tillers and early yellowing of leaves, appropriately increase the nitrogen application rate by 10%—30% to promote the weak to become strong; for fields with an excessive number of population stems and tillers, darker leaf color, and drooping leaves, reduce the application or do not apply based on the seedlings at the 3rd or 2nd leaf from the top stage; for areas retaining ratoon rice, apply 10 kg of urea per mu about 10 days after full heading of the main crop to promote the sprouting of ratoon buds.

3. Spray fertilizer on leaves to alleviate the effects of high temperature

For the main crop of ratoon rice or single-season middle rice at the heading to full heading stage, after high temperatures, measures such as foliar spraying of phosphorus and potassium fertilizers can be adopted. Generally, a 0.2% potassium dihydrogen phosphate solution or a 3% superphosphate solution is used for foliar spraying to enhance rice stress resistance, reduce high-temperature damage, promote grain filling, and improve seed-setting rate and 1000-grain weight; for fields with particularly low seed-setting rates in the later stage, if the subsequent crop allows, nitrogen fertilizer can be appropriately topdressed to promote tillering of dormant buds at lower nodes into panicles and compensate for yield losses.

4. Unified prevention and control to strictly control disease and pest damage

Strengthen disease and pest monitoring and forecasting, and accurately grasp the dynamics of disease and pest occurrence. During the critical period of disease and pest occurrence around the heading stage, focus on controlling rice planthoppers, rice leaf rollers, rice blast, rice false smut, and sheath blight, vigorously promote specialized unified prevention and control, improve the level of green prevention and control, reduce pesticide dosage, and reduce disease and pest losses.