What effects does hazy weather have on vegetables in solar greenhouses
????1. Adverse effects
The main problem is insufficient light and lower temperatures, which are not conducive to vegetable growth. Next is high air humidity, which increases the incidence of vegetable diseases. Besides these two more obvious harms, there is another one: hazy weather contains more pollutants in the air. Through ventilation and other farming activities, these pollutants fall onto the leaves and clog the stomata, affecting the photosynthesis and respiration of vegetable leaves, thereby affecting crop growth.
?2. Management measures
1. Be prepared and prevent in advance. First, develop the habit of listening to the weather forecast, and before hazy days arrive, do the watering and fertilizing work well, cultivate strong seedlings and strong plants, accumulate nutrients, and improve plant resistance. Second, improve the level of hardware facilities, such as using anti-fog drip films and installing supplemental lights.
2. Light management. During the day, the thermal insulation quilt (straw mat) should be uncovered as much as possible so that the vegetables receive scattered light. Where conditions permit, artificial supplemental lighting measures such as light irradiation and installing plant grow lights can be adopted to minimize the impact of hazy weather on greenhouse vegetables. After the temperature inside the greenhouse rises, ventilate appropriately to exchange the air and reduce the humidity inside the greenhouse.
3. Fertilizer and water management. Fertilizer and water management. During hazy weather, try not to water or topdress, so as not to lower the ground temperature and increase the humidity inside the greenhouse. If watering is really necessary, irrigate with a small amount of water and ventilate in time to remove moisture. In addition, it is recommended that vegetable growers try not to fertilize and to water less during the two months of December and January. Watering will lower the temperature and raise the humidity, which first leads to slow vegetable growth and second increases the occurrence of vegetable diseases. It is recommended to do one thorough watering in late November and apply one heavy fertilizer application.
4. Pest and disease control. Hazy weather easily induces fungal diseases such as gray mold, leaf mold, and blight, as well as bacterial diseases such as angular leaf spot, in greenhouse vegetables. Active measures should be taken, with prevention first and combining prevention with control, to control the occurrence of pests and diseases. For chemical control, smoke agents should be given priority; if spray control is needed, choose symptomatic and sensitive pesticides. For example, for powdery mildew, first choose sulfur formulations, and use a compound agent of triadimefon and thiophanate-methyl to spray thoroughly in one application, to the point where it feels like liquid is dripping from the leaves, and 80-90% can be cured in one application; for downy mildew and blight, first choose copper formulations. Remove moisture in time to reduce the humidity inside the greenhouse. On foggy days, daytime air humidity is high, and the water in the leaves is not easily transpired out, causing the roots not to absorb water. At this time, the fertilizer elements transported to the leaves through water cannot be delivered upward, which easily leads to nutrient deficiency in the roots and leaves, resulting in symptoms of yellowing leaves or yellowing leaf edges. In this case, applying fertilizer only to the soil does not have much effect. Although there is a lot of fertilizer in the soil, the root system does not absorb it. At this time, foliar topdressing should be used to supplement the problem of nutrient deficiency above ground. Foliar topdressing should pay attention to the reasonable ratio of nitrogen, phosphorus, potassium, and trace elements. It is recommended to spray brassinolide and monopotassium phosphate, which have high utilization rates.