Key Cultivation Techniques for Machine-Transplanted Rice at the Transplanting Stage

I. Make a Good Start and Manage the Seedling Nursery Well

1. Apply the "standing-up fertilizer" according to seedling appearance. This is generally done 3-4 days before transplanting; the amount and method of application should depend on seedling color. For weak seedlings with faded leaf color, use 4-4.5 kg of urea per mu diluted in 200 kg of water, and spray or splash evenly in the evening; after application, sprinkle clean water once to prevent fertilizer burn to the seedlings. For seedlings with normal leaf color and upright leaves that do not droop, use 1-1.5 kg of urea per mu diluted in 60-70 kg of water for foliar spraying. For seedlings with dark green leaves and drooping leaves, do not apply fertilizer at all; water control measures should be taken to improve seedling quality.

2. Control water at the right time to harden the seedlings. This is generally done 3 days before transplanting. Water control method: keep half a ditch of water on sunny days; if the seedlings curl their leaves at noon, sprinkle water to replenish moisture. On cloudy and rainy days, drain the accumulated water in the seedling ditch. Especially before lifting the seedlings for transplanting, cover with film to shield from rain before rainfall, to prevent the tray soil moisture content from being too high and affecting seedling lifting and transplanting.

3. Apply the "standing-up pesticide" thoroughly. Because machine-transplanted rice seedlings are small and tender, they are susceptible to damage from pests such as stem borers, small brown planthoppers, and rice thrips, so a full application of the "standing-up pesticide" is required. Apply 50 ml of 5% fipronil per mu diluted in 50 kg of water by small-machine spraying 2-3 days before transplanting.

II. Carry Out Transplanting with Meticulous Care

1. Fine tillage and land preparation. First, timing must be early. Machine-transplanted small seedlings have little flexibility in seedling age, so field tillage and preparation must be done as early as possible; better to have the field wait for the seedlings than to have the seedlings wait for the field. Second, land preparation must be level. The field surface is required to be level, with a total field height difference of no more than 3 cm, surface soil moderately firm and soft, and no weeds or debris on the field surface. Third, appropriately reduce the amount of straw returned to the field. Generally, the amount of straw returned to the field per mu should not exceed 200 kg. Fourth, the soil should be allowed to settle appropriately before machine transplanting. Generally, a settling time of about 1 day is required. Before transplanting, irrigate a thin layer of water, with a water depth of 1-2 cm.

2. Apply sufficient base fertilizer. Base fertilizer application should be based on factors such as soil fertility and cropping rotation, and adhere to the principle of combining organic fertilizer with inorganic quick-acting fertilizer. The application rate is generally 45%-50% of the total fertilization amount, to meet the nutrient needs of rice during early and mid-stage growth.

3. Reasonable density. Conventional varieties require higher density, with a row-to-plant spacing of 30 cm x 12 cm being suitable, and an actual density of 17,000-17,500 hills per mu; for hybrid japonica rice, the transplanting density is about 15,000 hills per mu.

III. Vigorously Manage the Field

1. Scientific water and slurry management. Insist on shallow-water transplanting. During the seedling-establishment and green-return stage, inch-deep water is required to protect the seedlings. In fine weather, irrigate during the day and expose at night; avoid both drying out and flooding. After the plants establish themselves, appropriately drain the field to expose the soil, and correspondingly extend the field-drying time.

2. Apply tillering-promoting fertilizer early. Combined with chemical weed control, apply 5 kg of urea per mu as tillering-promoting fertilizer.

3. Insist on two chemical weed control treatments. Generally, 5-7 days after transplanting, use a bensulfuron-methyl and butachlor compound agent for the first chemical weed control, then after 1 week use a bensulfuron-methyl and acetochlor compound agent for the second chemical weed control. After application, maintain a water layer in the field to improve the chemical weed control effect.

4. Prevent and control early-stage pests and diseases well. After machine-transplanted small seedlings are transplanted to the field, close attention must be paid to the damage from rice thrips and rice weevils, and control should be organized promptly.