Potato virus-free seed breeding technology
Source: Seed Technology
Category: Technical Articles
Update Time: 2008-10-29 16:13:05
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By Shen Qingling (Huzhu County Seed Management Station)
The promotion and use of virus-free seed potatoes is a key strategy for increasing potato yields. The quality of the seed directly impacts field performance, making it crucial to maintain the genetic purity of virus-free varieties and prevent viral infections or degeneration. This is essential in producing high-quality, disease-resistant seed potatoes.
**1. Preparation of Original Seeds**
High-purity, detoxified seed potatoes are selected from specialized units that produce virus-free seeds. These should be of uniform size, around 20–30 grams, with smooth skin, no cracks, no sprouting, and no insect damage. Approximately 90–120 kg per mu is prepared. Whole tubers must be used, and mulching techniques are not recommended during planting.
**2. Selection of Planting Sites**
Ideal sites are cool, humid, and well-ventilated, with easy access and no locust infestations. They should be located away from cruciferous crops or have natural barriers to prevent cross-contamination. The soil should be fertile, loose, and evenly nourished. The area should be open and flat, with no non-detoxified varieties or multiple types of detoxified varieties planted nearby to avoid reinfection.
**3. Deep Plowing**
Deep plowing improves soil structure, enhances organic matter decomposition, and increases water retention. It should be done when soil moisture is between 40% and 60%, at a depth of 20–30 cm. This process is often combined with chemical soil treatments and fertilization.
**4. Balanced Fertilization**
Potatoes require rich nutrients, so organic manure is essential. However, it must not contain leaves from solanaceous plants like potatoes. Virus-free seed potatoes grow vigorously and need sufficient base fertilizer. Typically, 5,000 kg of organic fertilizer is applied, along with 23 kg of pure nitrogen, 4.6 kg of phosphorus pentoxide, and 26 kg of potassium oxide per mu. Top-dressing with compound fertilizer (5–10 kg per mu) or foliar spraying with 0.3% potassium dihydrogen
Phosphate solution is recommended before flowering.
**5. Sowing Practices**
5.1 **Planting Density**: Aim for 4,500–5,500 plants per mu, with spacing of 50–65 cm between rows and 25–35 cm between plants.
5.2 **Sowing Date and Depth**: Sow when the soil temperature reaches 7–8°C at a depth of 10 cm. In Qinghai Province, sowing typically occurs from late April to early May, with a depth of 8–12 cm.
**6. Field Management**
6.1 **Soil Cultivation and Weeding**: Virus-free seed potatoes grow quickly, so timely weeding and soil loosening are important. Manual weeding helps raise soil temperature and strengthen plant growth. When seedlings reach about 20 cm, the second earthing-up is performed before mulching.
6.2 **Removal of Diseased Plants**: Inspections should be conducted at the seedling, budding, and flowering stages, as well as 20–25 days after. Diseased, mixed, or weak plants must be removed. During harvest, all infected or damaged plants are strictly excluded.
6.3 **Pest Control**: Use pesticides to manage underground pests such as earthworms and beetles. In cases of late blight, affected plants should be sprayed promptly to control the spread of the disease.
**7. Harvesting and Storage**
Harvesting should be done carefully, avoiding mechanical damage and frost. After harvesting, allow the tubers to air-dry for one or two days. When storing, handle them gently to prevent bruising. The ideal storage temperature is 2–4°C with 80% humidity. Ensure proper ventilation to maintain freshness and prevent rotting or premature sprouting. Different varieties should be stored separately. The storage pit should be cleaned and disinfected one month prior to harvest. During storage, monitor for freezing, moisture, and contamination to ensure high-quality seed potatoes.
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