Latest Technical Points for Late-Stage Field Management of Rice

Protecting the stems and leaves well, preventing premature senescence, enhancing the photosynthetic efficiency of rice plants after heading, and promoting high accumulation and high translocation of nutrients are among the key measures for achieving high yield and high quality in hybrid rice.

Supplementary application of grain fertilizer

After hybrid rice heads, the functional leaves gradually turn yellow and wither. If fertilizer is deficient, the leaves will also yellow prematurely and die, and the photosynthetic capacity of the rice plant will be weakened. Therefore, supplementing fertilizer to increase the source, extending leaf lifespan, and improving leaf photosynthetic capacity is one of the effective measures to promote more and fuller grains. The application of grain fertilizer is generally based mainly on foliar spraying of leaf fertilizer, sprayed 2 to 3 times from the breaking stage to the grain-filling stage, using 100 grams of monopotassium phosphate and 0.5 to 1 kg of urea per mu each time, dissolved in 50 kg of water, then adding 15 to 20 ml of 802 and mixing before spraying evenly on the stems and leaves of the rice plants. For fields with insufficient base fertilizer and where leaves show nitrogen deficiency and yellowing relatively early, it is advisable to apply 2.5 to 4 kg of urea per mu as a topdressing before heading, which can promote further differentiation of flower buds and prevent degeneration of spikelets, giving full play to the large-panicle advantage of hybrid rice.

Regulating water

Hybrid rice has stricter water requirements during the heading and flowering stage. The heading and flowering stage is most susceptible to damage from high temperatures, so appropriate deep irrigation should be carried out to increase field humidity, lower temperature, and promote uniform heading and normal flowering and pollination. If abnormally high-temperature weather occurs, clean water should also be sprayed to improve the microclimate of the panicle layer and reduce the impact. After heading, the plant root system ages, so under the condition of ensuring water supply, opportunities for soil aeration should be increased, using air to nourish the roots, and nourishing the roots to protect the leaves, preventing root decline and leaf failure. From heading to the early pollination stage, a certain water layer should be maintained in the field to meet the physiological water requirements of the plants; afterward, moist irrigation should be maintained, managing water according to the principle of alternating dry and wet. During the grain-filling stage, wet conditions should predominate; during the dough stage, dry conditions may predominate; alternate dry and wet until maturity. Water must never be cut off too early, otherwise it will also artificially cause premature senescence, resulting in reduced yield and lower rice quality. Generally, it is advisable to cut off water about 5 days before harvest.

Prevention and control of diseases and pests

Diseases and pests are severe in the late stage of hybrid rice and are important factors affecting “protecting the sink”, “strengthening the source”, and “smooth flow”. They are obstacles to achieving high yield and high quality and must be controlled in a timely manner to protect the stems and leaves from damage. The main leaf-destroying diseases and pests of hybrid rice include late-stage syndrome, rice blast, bacterial leaf blight, and rice leaf roller. The main stem-damaging diseases and pests include sheath blight, rice planthopper, and stem borers. Emphasis should be placed on controlling late-stage syndrome, because it is the result of a mixture of multiple fungal diseases and often causes leaf scorch, damaged leaf tips, and severe premature senescence, which can reduce rice grain by about 20%, so vigorous prevention is required. At the breaking stage, use 50 to 75 grams per mu of 40% Hekuling or Yelubao wettable powder, dilute with 50 kg of water, and spray evenly on the stems and leaves of the rice plants, which can achieve significant effects in preventing disease, protecting leaves, and preventing premature senescence. For areas where rice blast frequently occurs and areas affected by bacterial leaf blight, to prevent disease onset, tricyclazole, yekuning, and other appropriate agents can be added at the breaking stage for mixed spraying.

Spraying boron fertilizer

During the flowering and seed-setting stage of hybrid rice, an adequate supply of boron fertilizer can increase the seed-setting rate and increase 1000-grain weight. According to experiments, spraying boron fertilizer solution in the late stage of hybrid rice can increase the seed-setting rate by 4.3% and increase the 1000-grain weight by 0.5 to 1 gram. Therefore, in boron-deficient fields or rice fields following rapeseed, it should be sprayed once each at the initial heading stage and full heading stage, and can be mixed with grain fertilizer spraying. Use 100 grams of borax or 100 grams of photosynthetic micro-fertilizer per mu each time, dilute with 50 kg of water, and spray evenly. When preparing the borax solution, first fully dissolve the borax with a small amount of warm water, and spray promptly after mixing.