Guangzhou Fuerle Health Technology Co., Ltd , https://www.fuerlegroup.com
Treating Rice Seedlings with Prescriptions
Rice seedlings, also known as "stuck seedlings," refer to a condition where the roots of transplanted rice plants fail to develop properly. This leads to slow emergence of new leaves and tillers, stunted growth, clustered plant structures, and dark green or red-brown spotted foliage. The causes of this phenomenon are varied, and accurate diagnosis is crucial for effective treatment. A combination of visual observation, soil analysis, and understanding the environmental conditions can help identify the underlying issue and apply the right remedies.
1. **Zinc Deficiency Seedlings**: These typically appear 2–4 weeks after transplanting, with symptoms peaking around day 20. New leaves show yellowish or white bases, while older leaves display brown spots along the veins. The lower leaves may have dry tips, and the new leaves are short and narrow, leading to dwarfed plants. Farmers call this "shrinking seedlings." To treat it, apply 1–2 kg of zinc sulfate per mu during the early stages, or spray 0.2% zinc sulfate solution (50–70 kg per mu) every 7–10 days, preferably in the morning or late afternoon.
2. **Potassium Deficiency Seedlings**: These usually occur after the rice turns green, with peak symptoms appearing 20–30 days post-transplanting. Symptoms include stunted growth, dark green leaves, and fewer tillers. Lower leaves develop yellow-brown to reddish-brown spots from the tip to the base. In severe cases, leaf margins may rupture and die. Apply potassium chloride or potassium sulfate at 10–20 kg per mu, or use 200 kg of wood ash to replenish potassium levels.
3. **Phosphorus Deficiency Seedlings**: Affected plants show dark green new leaves and purplish-red coloration on older leaves. Leaves are small, erect, and the sheaths are long. Root systems are weak, with few white roots. To address this, apply calcium phosphate or superphosphate at 30–50 kg per mu, or use 7–10 kg of diammonium phosphate. Foliar sprays of 2% superphosphate solution can also be applied every 7 days for two applications.
4. **Toxicity and Freezing Seedlings**: After transplanting, if the plants fail to green up quickly, they may exhibit yellowing, stunted growth, and root damage. Dark brown, deformed roots and a foul-smelling soil are common signs. To manage this, perform deep water flushing to remove toxins, then rinse with clean water. Drain the field to improve aeration and promote root health. Apply phosphorus and potassium fertilizers to enhance root development, and later use quick-acting nitrogen to boost growth.
5. **Soil Sogging**: Common in fields with poor drainage, especially those with deep mud or cold water. The planting depth becomes too deep, causing roots to grow upward and delaying recovery. Prevent this by draining excess water, increasing soil aeration, and warming the soil to improve root development and overall plant health.
6. **Cold Damage Seedlings**: Caused by low temperatures after transplanting, such as cold flooding or rainy weather. Symptoms include slow growth, yellow-brown roots, and brown spots on leaf tips. Severe cases may result in "knotty white" or "knotty yellow" appearance. To mitigate this, drain water, adjust irrigation water temperature, and use water to insulate the field. Nighttime irrigation can also help raise soil temperature.
7. **Herbicide Injury**: Excessive use of certain herbicides like sulfonylureas or chlorpyrifos can lead to abnormal root development, yellowing leaves, and stunted growth. Prevention involves reducing the use of these chemicals and using alternatives. If injury occurs, drain the field and wash it with water to reduce residual herbicides in the soil.
8. **Pests and Diseases**: Uncontrolled pests like rice blast or thrips can cause delayed growth and reduced tillering. Treatments include applying tricyclazole, triazophos, or omethoate according to recommended rates. Regular monitoring and timely spraying are essential to prevent severe infestations.
In addition, for severely affected fields, growth regulators such as "squiggly seedlings" or "stiff seedlings" can be used to stimulate plant recovery and restore normal growth. Each case requires a tailored approach, ensuring that the specific cause is addressed effectively.