What is japonica rice? Differences from indica rice, suitable regions, and cultivation methods

Japonica rice is a variety of rice. Because its grains are large, its milling yield is high, and it does not break easily during processing, it is deeply loved by people. It is currently planted in Northeast China and the Yellow River basin, and also in the South, but due to temperature limits, it rarely survives there. So what is japonica rice? What is the difference from indica rice? Which regions is it suitable for planting? How is it planted?

The milled rice produced from japonica rice is called “japonica rice”. In some places, “japonica rice” is called “rice”; in fact, japonica rice is only one variety of rice (paddy rice).

Differences from indica rice:

1. Suitable planting latitudes differ

Indica rice is suitable for planting in low-latitude, low-altitude hot and humid areas. Its grains fall off easily, and it is relatively tolerant of moisture, heat, and strong light, but not cold; japonica rice is more suitable for planting at high latitudes or at high altitudes in low latitudes. Its grains do not fall off easily, and it is relatively tolerant of cold and weak light, but not high temperatures. Therefore, the later season of the double-cropping rice area in the middle and lower reaches of the Yangtze River and areas north of the Yellow River generally use japonica rice varieties.

2. Rice properties and grain shape differ

Generally, indica rice has weaker stickiness and a long, narrow grain shape; japonica rice is sticky and its grains are short and round.

3. Plant architecture and leaf color differ

Japonica rice has shorter stems, narrower leaves, upright tillers, darker green leaves without hairs, a relatively hard texture, shorter leaves with a smaller angle to the stem, a longer inflorescence main axis, more spikelets, dense panicles, heavy panicles, and longer and denser glume hairs. Indica rice plants are about 100 cm tall, with light green leaves, long and wide flag leaves, a loose but moderate plant type, slender grains, and colorless glume tips with short awns.

Suitable planting regions:

Japonica rice is more suitable for planting at high latitudes or at high altitudes in low latitudes. Its grains do not fall off easily, and it is relatively tolerant of cold and weak light, but not high temperatures. Therefore, the later season of the double-cropping rice area in the middle and lower reaches of the Yangtze River and areas north of the Yellow River generally use japonica rice varieties. In addition, in China's total japonica rice production, the japonica rice of the three northeastern provinces and Jiangsu plays a pivotal role.

Cultivation techniques:

1. Seed soaking and germination acceleration

Before soaking the seeds, choose sunny weather and sun the seeds for 1-2 days. Soak the seeds in chemicals to prevent bakanae disease; accurately grasp the amount of chemicals, water, seeds, and soaking time. Before the seeds break white, pay attention to moisture retention and air permeability; generally, do not sprinkle water. After they break white, promote rooting at suitable temperature and promote germination while maintaining moisture.

2. Sow at the right time and cultivate strong seedlings

For direct-seeded single-season rice fields, sowing in early June is suitable, with a seeding rate of 37.5-45.0 kg/hm2, using short sprouts for sowing, and note that the seeding rate must not be too large. For machine-transplanted rice, sowing and raising seedlings on May 25, and transplanting in mid-June are suitable, with seedling age controlled at 15-20 days, sowing rate of 80-1OOg/tray, 450 trays/hm2. Transplant at the right time, preferably at the 3.0-leaf age; the machine transplanting specification is 30cm ×16cm, with 2 seedlings per hill, and effective panicles controlled at 3.15 million/hm2.

3. Appropriate nitrogen and increased potassium, rational fertilization

For Jia 58, applying nitrogen fertilizer equivalent to 450-525 kg/hm2 urea and 187.5 kg/hm2 potassium fertilizer is suitable. The application ratio of nitrogen fertilizer as basal, seedling, stem-strengthening, and panicle fertilizer is best at 30:30:20:20. Apply stem-strengthening fertilizer cautiously, and apply panicle fertilizer at the right time and in the right amount. When Jia 58 is used for high-quality rice production, medium fertilizer cultivation is advocated, fully improving maturity and milling yield, and appropriately reducing chemical fertilizer and pesticide application.

4. Water management

Water management should follow the principles of shallow-water irrigation in the early stage to promote low-position tillering and suppress high-position tillering; in the middle stage, sufficient water for booting, flowing water during flowering, and moist irrigation during grain filling; in the later stage, frequent light irrigation and not cutting off water too early. When the number of seedlings in the field reaches 2.85-3.00 million seedlings/hm2, field drying should be carried out in several light sessions in a timely manner to control ineffective tillering. From the young panicle differentiation stage to the early grain-filling stage, irrigate shallowly and frequently, alternating dry and wet. Except when applying 5 cm or so of water for disease and pest control, generally maintain a thin water layer for irrigation; after one release of water, wait for it to dry naturally before irrigating again. In the middle and late grain-filling stages, alternate dry and wet. In the later stage, strictly prevent cutting off water too early, so as to improve the seed-setting rate and 1000-grain weight, thereby achieving the goal of high quality and high yield.

5. Disease and pest control

According to seedling conditions and forecasts, during the main field period, do a good job in controlling diseases and pests such as rice leaf roller, stripe disease, small brown planthopper, brown planthopper, and rice false smut according to the disease and pest information from plant protection departments. Jia 58 has strong tillering; in the early stage, “Mansui” should be selected, and in the later stage, “Aimiao” should be used to strengthen control of sheath blight. Because Jia 58 is susceptible to brown planthopper, attention should be paid to brown planthopper damage during the grain-filling and milk-ripening stage to ensure a bumper harvest.

6. Harvest at the right time

Harvest in time when field maturity reaches 90%-95%. When drying grain, spread it evenly and turn it frequently; the suitable thickness for drying grain is about 13 kg/m2, and the rice can be dried until the moisture content is about 14%. This avoids drying the rice too quickly, increasing the number of cracked grains and reducing the processing quality of Jia 58 rice.