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Vegetable seedlings must be "eight defenses"
Vegetable seedlings play a crucial role in the growth of vegetables, serving as the foundation for early maturity, high yield, and quality production. During the seedling stage, several common issues may arise that can negatively impact their development. It's important to be aware of these problems and take preventive measures accordingly.
One common issue is poor seed quality, bacterial infection, improper watering, or prolonged low temperatures after sowing. These conditions can lead to seed rot, dry shoots, and delayed emergence. To prevent this, conduct germination tests before planting, use high-quality seeds, disinfect spare seeds, and maintain proper temperature and humidity levels to ensure healthy seedlings.
Another problem is "top shell" seedlings, where the seed coat fails to fall off after germination, causing the cotyledons to be trapped. This condition, often seen in melon crops, leads to weak seedlings and reduced photosynthesis. Causes include shallow sowing, dry soil, immature seeds, or premature removal of protective covers. To avoid this, ensure adequate moisture before germination, sow at the correct depth, and water gently when the first shoots appear.
"Leggy" seedlings, also known as "high-legged" seedlings, are characterized by thin stems, long internodes, and weak root systems. This occurs due to insufficient light, overcrowding, excessive nitrogen, or high nighttime temperatures. Preventive actions include controlling fertilization, ensuring good ventilation, increasing light exposure, and removing weeds promptly.
"Aging" seedlings, or stiff seedlings, show slow growth, small size, and aged roots. They are often caused by low temperatures or water deficiency. Such seedlings struggle to survive after transplanting. To prevent this, maintain proper temperature and humidity, avoid overlong nursery periods, and act quickly if aging symptoms appear.
Root damage can occur due to low temperatures, excessive moisture, or improper fertilization. Symptoms include root rot, wilting, or burnt roots. Preventive steps involve balanced fertilization, controlled moisture, and maintaining suitable environmental conditions.
Poisonous gas contamination from plastic films or excessive fertilizer application can harm seedlings, causing leaf discoloration, drying, and even death. Cruciferous crops like cauliflower and cabbage are particularly sensitive. To prevent this, use certified safe films, ventilate regularly, and avoid overuse of organic or nitrogen-rich fertilizers.
Cold damage, often referred to as "flood-proof" seedlings, can occur due to sudden temperature drops, heavy rain, snow, or improper facility management. Symptoms include white spots on leaves and dehydration. Preventive strategies include strengthening seedlings through proper lighting, adjusting humidity, and preparing for cold weather in advance.
Lastly, pest control is essential. Before sowing, disinfect seeds and treat the soil to prevent diseases like damping-off, blight, and gray mold. Also, manage pests such as aphids, mites, and locusts using integrated agricultural and biological methods, avoiding the use of highly toxic chemicals.
By understanding and addressing these issues, growers can significantly improve seedling health, leading to better crop performance and higher yields.