Technical Opinions on Field Management of Early Rice in Southern China at the Mid-to-Late Stage

Currently, early rice in southern China has entered the mid-to-late stage of field growth, with the South China region entering the grain-filling stage and the middle and lower reaches of the Yangtze River entering the jointing and booting stage. In response to the current population growth of early rice and climatic characteristics, the Rice Expert Steering Group of the Ministry of Agriculture and the National Agricultural Technology Extension Service Center, after consultation, put forward technical opinions on field management of early rice in southern China at the mid-to-late stage.

First, rational fertilization to promote growth. Fertilizer should be applied according to local conditions and seedling conditions to promote early tillering and rapid growth. For the third-category seedlings that were sown and transplanted late, an additional tillering-preserving fertilizer should be applied once to promote balanced growth. For the first- and second-category seedlings, the focus should be on applying spikelet-grain fertilizer, mainly flower-preserving fertilizer, applied at the stage of the second leaf from the top to prevent spikelet degeneration, extend the length of the top two leaves, and promote tillering into productive panicles. For fields with a relatively small population, fertilizer can be applied earlier when the third leaf from the top emerges, so as to combine flower promotion and flower preservation. According to the growth of rice plants in the field, nitrogen and potassium fertilizers should be applied in a timely manner to increase the number of effective panicles and grains per panicle; generally, 3-5 kg of nitrogen fertilizer and 3-5 kg of potassium fertilizer are applied per mu. If the leaf color is light green at the heading stage, grain fertilizer should be supplemented, generally 1-2 kg of nitrogen fertilizer per mu, or 200 g of potassium dihydrogen phosphate plus 250 g of urea diluted in water for foliar application, so as to enhance photosynthetic capacity in the late stage and promote grain filling and seed setting.

Second, scientific water management to build the population. Overall, it is necessary to ensure water for panicle development at the mid-growth stage and alternate wetting and drying at the late stage to plump the grains. In case of heavy rainfall, drainage and exposure of the field should be carried out promptly. For late-developing fields that have not yet been drained for sun-drying, the principle of "when the time comes, do not wait for the seedlings" should be adhered to, and water and seedling control should be carried out in a timely manner to avoid excessive population caused by being too sparing with water and seedlings. For rice fields where sun-drying has been completed, intermittent wetting and drying irrigation should be adopted after re-flooding to promote root growth. During the heading stage, shallow-water irrigation should be used to ensure heading with water, which is conducive to uniform heading and consistent maturity. After heading, intermittent wetting and drying irrigation should be adopted, and water should be cut off about 5 days before harvest; cutting off water too early must be avoided to prevent premature senescence and high-temperature forced ripening.

Third, integrated control of pests and diseases. Affected by the warm winter last year, the field pest and disease base and the population of overseas rice planthoppers were relatively large, and pests and diseases may occur more severely in the mid-to-late stage of early rice. The focus should be on the control of the migratory "two pests" (rice planthopper and rice leaf roller) and the "two diseases" (rice blast and rice sheath blight), vigorously promoting centralized and contiguous unified prevention and control to improve control effectiveness and reduce pesticide use. Pest and disease monitoring should be strengthened, and the number of surveys should be appropriately increased according to weather changes to grasp the occurrence of pests and diseases, and promptly report pest and disease information, application timing, pesticide selection, and dosage. A key control operation should generally be carried out at the breaking stage of early rice to ensure that no major pests or diseases occur in the field at the mid-to-late stage.

Fourth, timely harvest to secure a bumper yield. Harvesting early rice too early affects yield and quality, while harvesting too late affects the arrangement of the next crop. The harvest period is generally about 25 days after full heading, when the entire panicle loses its green color and 90% of the glumes turn yellow. During the harvest period of early rice in southern China, severe weather such as high temperatures and rainstorms often occurs, and sprouting in the panicle can easily cause yield reduction and quality decline. Farmers should be guided to harvest at the right time, prevent "green cutting," and ensure full maturity. Vigorously promote mechanized combine harvesting and threshing with straw crushing devices to improve harvest efficiency and achieve grain recovery in every kernel.