Technical Recommendations for Defending Against High Temperatures During the Late Growth Stage of Early Rice in Southern China in 2018
Right now, most regions of China have entered the high-temperature season, and many crops are already difficult to grow, while early rice in southern China is currently at the grain-filling and ripening stage, which is a critical period for yield formation. So to achieve high yields, it is also necessary to avoid the various diseases brought by high temperatures. So how should early rice in southern China prevent high temperatures during high-temperature periods?
According to meteorological forecasts, the Jiangnan region will experience persistent high-temperature weather, with maximum temperatures in some areas reaching 37—38°C, and locally up to 39—40°C, and the number of high-temperature days may last 6—8 days. Persistent high temperatures are unfavorable for rice grain filling and ripening and affect the 1000-grain weight. In response to the current growth conditions of early rice and the meteorological characteristics, the Rice Expert Steering Group of the Ministry of Agriculture and Rural Affairs, together with the National Agricultural Technology Extension Service Center, put forward technical recommendations for defending against high temperatures during the late growth stage of early rice in southern China in 2018.
1. Regulate temperature with water to lower canopy temperature
When early rice at the grain-filling and ripening stage experiences persistent high-temperature weather above 35°C, deep water can be irrigated into the field, maintaining a 5—6 cm water layer to increase field humidity and improve the “microclimate” of the paddy field; daily irrigation and nighttime drainage can also be adopted to accelerate transpiration from rice leaves and lower canopy temperature. Be sure to avoid cutting off water too early in the later stage and causing high-temperature forced ripening.
2. Apply grain fertilizer as a topdressing to promote recovery growth
After the high-temperature weather passes, for lightly damaged fields, field water and fertilizer management should be strengthened to promote grain filling, increase grain weight, and reduce losses; for severely damaged fields, grain fertilizer should be applied as a supplementary dressing according to seedling condition, with 2—3 kg of urea per mu or foliar fertilizer spraying, to delay leaf yellowing and senescence, enhance photosynthetic capacity in the later stage, promote grain filling and ripening, and ensure safe maturity.
3. Strengthen monitoring and do a good job in disease and pest prevention and control
Under high-temperature and high-humidity conditions, diseases and insect pests are prone to worsen. Monitoring and early warning should be strengthened, and prevention and control of diseases and pests should be reinforced with emphasis on the rice “two migrations” pests, rice blast, and sheath blight. Green prevention and control and unified prevention and control should be vigorously promoted to improve control effectiveness, reduce pesticide dosage, and effectively reduce losses from diseases and insect pests.
4. Harvest in a timely manner to prevent sprouting on the panicle
During the harvest period of early rice in southern China, there is more rainy weather, and sprouting on the panicle is likely to occur, resulting in reduced yield and declining quality. Material and technical preparations should be made early, and harvesting should be done in a timely manner by seizing clear weather. Vigorously promote the operation of combine harvesters equipped with stem chopping and scattering devices to facilitate straw return and stubble burial and improve harvest efficiency. Generally, harvest when about 25 days after full heading, when the entire panicle has lost green color and 90% of the glumes have turned yellow. After early rice harvest, it should be dried promptly or sun-dried to the standard moisture content, and centralized drying is encouraged to avoid mold.