What are the management measures for rice during the jointing and panicle elongation stage?

Currently, rice growth across the city has successively entered the jointing and panicle elongation stage, an important period of transition from vegetative growth to reproductive growth and a critical period that determines yield. Doing a good job of field management in the middle and late stages of rice is crucial for ensuring sufficient panicles, striving for large panicles, shaping a high-yield plant type, and building a good foundation for high yield.

I. Seedling growth characteristics

According to a survey on July 21, the average leaf age of machine-transplanted rice was 12.31 leaves, 0.49 leaves more than the same period last year; the average leaf age of direct-seeded rice was 10.31 leaves, 0.56 leaves more than the same period last year; the total number of stems and tillers was 386,300 seedlings per mu for machine-transplanted rice, a year-on-year decrease of 11,600 seedlings; for direct-seeded rice it was 512,800, a year-on-year increase of 9,000 seedlings. A comprehensive analysis of the early-stage foundation of this year's rice production reveals the following prominent problems:

First, the proportion of dry direct-seeded rice is relatively large. The city's dry direct-seeding area is close to 110,000 mu, accounting for about 34% of the total rice area. Extensive management is a serious problem, posing a considerable hidden risk to high and stable yields. In some dry direct-seeded fields, rice seedlings grow and develop slowly, are thin and weak as individuals, and do not produce enough seedlings during the effective tillering period.

Second, seedlings developed relatively quickly in the early stage. This year, temperatures were high during the plum rain period and after it ended, leaves emerged quickly, tillering was abundant, and small tillers and ineffective tillers increased accordingly.

Third, the imbalance in seedling growth is great. Due to the diversification of planting methods and the long sowing and transplanting cycle, the growth and development processes of rice seedlings are uneven, the differences in seedling growth are large, and management difficulty is increased. Fourth, field drying was not carried out adequately. In some fields, field drying was too light, the field surface was relatively muddy, and the rice plants were tender and poor in elasticity. In a few direct-seeded rice fields, the total number of stems and tillers per mu exceeded 500,000, and the population was too large, which is extremely unfavorable for field management in the middle and late stages and for shaping a high-photosynthetic-efficiency population.

Therefore, in view of the severe situation of rice production this year, all localities must act immediately, vigorously grasp field management in the middle and late stages of rice, ensure that all technical measures are implemented in place, stabilize the number of panicles, focus on large panicles, and strive for a bumper rice harvest.

II. Current key technical measures

1. Provide guidance according to seedling classification and apply rice panicle fertilizer skillfully. The varieties Ningjing 3 and Nanjing 44 planted this year are large-panicle varieties with high fertilizer demand in the later stage, and heavy application of panicle fertilizer is the key to achieving high yield. At present, with continuous high temperatures and strong sunlight, fertilizer consumption is high and rice seedlings grow quickly, and after jointing they will fade over a large area. All localities should mobilize early and prepare early, and conscientiously do a good job of applying rice panicle fertilizer according to the current rice leaf age process and seedling growth characteristics. At the same time, the application of rice panicle fertilizer this year should be suited to the seedlings, the preceding crop, and the sowing and transplanting method, with classified guidance and scientific management, advocating a one-time sufficient application of flower-promoting fertilizer and skillful application of flower-preserving fertilizer according to the seedlings.

Specific application time and amount: for water direct-seeded rice sown before June 1 and for throw-transplanted rice and machine-transplanted rice transplanted before June 5, apply 12.5-15 kg of urea per mu from July 25 to the end of July; for throw-transplanted rice and machine-transplanted rice transplanted after June 5, apply before August 1-5, and for direct-seeded rice sown after June 1, apply before August 5-10, 10-12.5 kg of urea per mu or 12.5-15 kg of high-efficiency compound fertilizer. For throw-transplanted rice and machine-transplanted rice, apply flower-promoting fertilizer no later than August 5, and for direct-seeded rice no later than August 15. On August 15-18, throw-transplanted rice and machine-transplanted rice should be appropriately applied with flower-preserving fertilizer according to the seedlings, with a fertilizer amount of 10-12.5 kg of high-efficiency compound fertilizer per mu. Principles for panicle fertilizer application: for throw-transplanted rice and machine-transplanted rice, apply both flower-promoting and flower-preserving panicle fertilizers well according to the seedlings; for direct-seeded rice, generally apply flower-promoting fertilizer well in the fields, and flower-preserving fertilizer is not advocated. At the same time, apply earlier where leaf color is light, appropriately delay application where leaf color is dark, appropriately reduce the amount in fields with large populations, and appropriately increase the amount where the population is insufficient.

2. Scientifically manage water and irrigation to enhance root vitality. The upper roots of rice and panicle differentiation occur simultaneously, and they are the main functional roots in the late growth stage of rice. Improving root vitality is an important physiological basis for high rice yield. In view of the fact that the overall effect of field drying this year is relatively poor, in the near future it is necessary to seize favorable weather and gaps between pest and disease control, continue to implement soft drying, light drying, and multiple dehydration drying of the field, and prevent the population from rebounding after rewatering following field drying. During the booting stage and the heading and flowering stage, a shallow water layer should be established; during the remaining stages, alternating dry and wet conditions and intermittent irrigation should predominate, ensuring clear water and a firm surface in the field, nourishing roots and preserving leaves, and improving root vitality. Cut off water 10 days before harvest, and by no means cut off water too early, which would affect rice quality and yield.

3. Do a good job of foliar fertilizer spraying to prevent premature senescence in the later stage. Spraying foliar fertilizer in the late growth stage of rice can optimize the canopy structure of rice plants, promote photosynthesis, improve photosynthetic efficiency, prolong the lifespan of upper functional leaves, effectively prevent premature senescence in the later stage, and achieve an obvious yield-increasing effect. In particular, this year a relatively large proportion of fields had stunted seedlings and delayed development in the early stage, and some fields are currently weak, yellow, and thin. All localities should, in conjunction with disease and pest control, vigorously publicize foliar fertilizer spraying, using it once each at the booting stage, the broken-neck stage, and the full-heading stage of rice, each time spraying 50-100 grams of foliar fertilizer per mu mixed with water, to nourish roots and preserve leaves, reduce degeneration, improve grain filling, and increase grain weight.

4. Comprehensively control pests and diseases to ensure safe production. The middle and late stages of rice production are the peak period for the occurrence and damage of major pests and diseases. All localities should, according to the forecasts and predictions of plant protection departments, pay close attention to the dynamics of pests and diseases during the panicle stage, and focus on waging an overall battle for pest and disease control. In the near future, it is necessary to make a special effort to control the rice leaf roller and sheath blight, and, according to a unified formula, implement unified prevention and unified control to comprehensively control pest and disease damage.

5. Base efforts on disaster resistance and mitigation to strive for a bumper harvest. The middle and late stages of rice production are also a period of frequent natural disasters such as typhoons, rainstorms, and hail. All localities should base themselves on resisting major and multiple disasters, prepare disaster resistance and relief plans early, and take preventive measures before trouble occurs. It is necessary to pay close attention to meteorological changes, promptly understand the occurrence trends of local and regional disasters, and do preventive work in advance. In field management, guide farmers to open a complete set of field ditches, both inside and outside, to ensure smooth drainage and irrigation. Formulate technical measures for stress resistance and contingency early to ensure timely recovery of growth after disasters and effectively reduce losses caused by disasters. At the same time, all localities should, in conjunction with high-yield rice creation activities, solidly manage high-yield rice demonstration fields, create high-yield models, and enhance the demonstration and radiating function of machine transplanting. It is necessary to conscientiously carry out investigation and research on different rice cultivation methods, do a good job of comparing the yield and benefits of direct-seeded rice and machine-transplanted rice, and lay a foundation for further transforming rice cultivation methods in the future and improving the comprehensive rice production capacity.