Winter and spring is the time of greenhouse vegetable seedlings and planting, because the seedlings are delicate, can not withstand the influence of external adverse factors, if you do not take countermeasures in time, the light will affect the growth of seedlings, and in serious cases, it can lead to dead seedlings and dead trees. Therefore, growers are reminded to detect problems as soon as possible and respond reasonably to ensure that the seedlings are strong and strong.
1. Manure seedlings burning: Winter and spring are the vegetable stubble periods, and they are also the more stages of manure seedlings burning. This ignores the problem that the manure fermentation is not complete, and the seedlings will also be burned. Some vegetable farmers think that the manure has been piled up outside the shed for a long time and has been completely decomposed, in fact, the manure piled up in the field can reach a semi-decomposed state at most, and the temperature in late autumn is not higher than the temperature in June and July.
It is difficult to achieve complete decomposition in 40 or 50 days, so it is applied to the soil in the shed and fermented for the second time under the condition of high temperature in the shed, resulting in the phenomenon of burning seedlings.
Countermeasures: Try not to use organic fertilizer that is not well rotted in winter and spring, and should make commercial organic fertilizer, with high fertilizer efficiency and insurance. The unrotted manure burns the roots and smokes the leaves, causing the leaves to wilt or dry up. When the seedlings are not serious, the mulch film should be removed in time, and the temperature of the shed should be released as much as possible to eliminate harmful gases in the shed. On consecutive sunny days, water is poured twice and functional fertilizers are applied to promote rooting. Foliar sprays can also be applied functional fertilizers such as amino acids and chitin foliar fertilizers to supplement various medium and trace elements to alleviate the deficiency caused by root injury and the air damage of leaves.
If the seedlings are burned severely, the seedlings die, and the whole leaves dry up, in this case, they should be directly uprooted and replanted. After uprooting, the temperature should be increased to promote the rapid decomposition of manure in a short period of time. Before replanting, ventilation should be carried out to release the harmful gases produced by the decomposition of the manure outside the shed.
Second, the roots. The shed is a closed microclimate, the humidity communicates less with the outside world, due to the low ground temperature in winter, the seedlings are planted after the new roots take root slowly, if the watering is excessive, the soil moisture and the humidity in the membrane are large, the ground temperature can not be raised, the root system is in a state of water saturation, the oxidation is reduced, and anaerobic respiration is carried out, resulting in the root system being injured, and if it catches up with the continuous rainy weather, it will cause the situation of the roots.
Countermeasures: Before the seedlings are planted, the shed should be closed all day to increase the ground temperature, so that the soil is slightly dry before opening the hole and planting. After planting, pour a small amount of planting water, and seal the seedlings after water infiltration, which can minimize the impact of drastic changes in surface temperature on the root system and avoid root damage. When watering in the future, choose to do it in the morning when the weather is fine, when the ground temperature is close to the water temperature, and it will not cause the phenomenon of rooting.
Immediately after the appearance of roots, hoeing is carried out to quickly reduce soil moisture. For mulching. In case of continuous rainy weather, the watering interval should be appropriately extended or not watered. After reducing soil moisture, use functional root nourishment fertilizer to irrigate the roots in time, and do a good job in the prevention of root diseases to prevent germs from taking the opportunity to infect the wound.
3. Apprenticeship. Plant growth is an obstacle to high yields, and the reason for growth is excessive fertilizer and water or even cloudy days. After the seedlings grow, the stalks are weak, the internodes are long, and the leaves are thin and yellow, which will affect the differentiation of flower buds and fruit set.
Countermeasures: After the seedlings grow, the control of the growth should be based on the degree of growth, and the commonly used measures to control the growth are temperature control, reducing the supply of fertilizer and water, adjusting the plant and squatting the seedlings. Vegetables in the seedling stage, due to their own nutrient requirements are small, and the bottom fertilizer application is sufficient, and the cultivation and squatting measures are managed. After entering the flowering and fruit-setting period, the plant grows fast, the nutrient demand is more, look at the seedling topdressing, try to use less high-nitrogen fertilizer, promote the reproductive growth of the plant, and prevent the vegetative growth from being too vigorous. At the same time, we should pay attention to root maintenance and apply more functional fertilizers to promote the healthy growth of plants. When the growth is more severe, plant growth regulators can be sprayed to control growth.
Fourth, low temperature chilling injury.
The plants in the shed have poor stress resistance, and once they encounter bad low temperature weather, no matter how good the heat preservation of the shed is, it is also limited, and it is easy to suffer from cold injury. The main ones are purple, white dry, yellowing, water stain symptoms, tabby leaves, leaf drooping, etc.
Countermeasures: Pay attention to the weather forecast, before the cold wave comes, do a good job of insulation in the shed in advance, such as sunny days to cover the insulation quilt in the morning and evening, in order to increase the light in the shed;On cloudy days, it is appropriate to cover the quilt late and early, and use warming measures.
Improving the stress resistance of the plant itself is also a measure to prevent chilling injury. Before planting, seedlings should be refined at low temperature, and adapted to low temperature in the shed for 4 to 5 days, and then planted. Before the cold wave comes, flush or irrigate functional fertilizers, such as chitin, amino acids, etc., to take root and strengthen the trees, and improve the resistance of the root system. Foliar spraying of glucose, chitin and other fertilizers has a good effect on improving the cold resistance of plants and reducing frost damage.
After the occurrence of cold injury, do not immediately see the light and raise the temperature, so as to avoid the sudden increase in temperature of the affected tissues, which will be more difficult to return to normal. At the same time, do not water and top dressing immediately, you can apply chitin, amino acids and other root-raising fertilizers 3 to 4 days after the weather improves to promote root regeneration.