In greenhouse cucumber cultivation, particularly as we move into April and temperatures start to rise, it’s crucial to ensure proper ventilation. Without timely ventilation or if ventilation is obstructed, greenhouse temperatures can soar to 40-50°C, sometimes even exceeding 50°C in the afternoon. Such extreme conditions can lead to significant damage to cucumber growth. Plants may exhibit stunted development, with leaves wilting and ceasing growth altogether. In severe cases, entire leaves can wilt, significantly impacting both yield and quality.
Symptoms vary depending on the growth stage. Seedlings exposed to high temperatures often show signs of stress, such as small, curled cotyledons, drooping leaves, and delayed flowering. Leaves may also become pale, large, and thin without proper expansion, while internodes stretch excessively. In mature plants, small circular to elliptical chlorotic spots initially appear on the leaves, gradually spreading outward. Within 3-4 days, the entire plant turns yellow from top to bottom, halting growth severely in extreme cases. Near the growth tip, leaflets may quickly wilt and develop dark margins when temperatures hit 48°C. Prolonged exposure leads to complete leaf wilting, resembling scorching by hot water.
One major cause of these issues is insufficient experience in cucumber cultivation. Many growers mistakenly pursue high temperatures, unaware that cucumbers are thermophilic but require specific temperature ranges for optimal growth. This oversight often results in temperatures exceeding safe thresholds. Additionally, after a cold winter, workers might neglect cooling measures, leading to sudden spikes in greenhouse temperatures, especially in the afternoon, when humidity drops drastically. Brief periods of overheating can harm leaves, whereas prolonged exposure risks killing the entire plant.
To prevent such damage, several strategies can be employed. First, maintain proper ventilation throughout each growth phase. For seedlings, daytime temperatures should be kept between 25-30°C, dropping to 16-18°C at night. As seedlings mature, adjust the temperature to around 30°C during the day and 16-14°C at night. During fruiting, aim for 28-30°C during the day and 16-18°C at night, keeping humidity below 85%. Regularly monitor temperature changes using thermometers and use vents or doors to cool the greenhouse when necessary. Watering should occur early in the morning to avoid night-time moisture retention, ensuring the water temperature remains close to the soil temperature.
Maintaining appropriate humidity is equally important. Ideal growth humidity for cucumbers is around 85%. When humidity exceeds this level, ventilate the greenhouse to reduce moisture. Ventilate for an hour in the evening if temperatures are between 18-20°C to prevent excessive growth and mitigate high-temperature stress. To curb legginess, apply 100% liquid solutions to flowers or fruits, promoting earlier maturity and reducing excessive elongation.
Supplemental phosphorus and potassium fertilizers, along with organic liquid fertilizers like potassium dihydrogen phosphate (0.2%) or urea (0.1%), can be applied two to three times via foliar spraying to enhance heat resistance. In prolonged high-temperature conditions or drought, cucumber plants experience increased water loss through evaporation and respiration. To counteract this, increase watering frequency and ensure deep irrigation every two days to keep plants hydrated.
Ultimately, careful management of temperature, humidity, and nutrition is key to overcoming heat stress in cucumber cultivation. These practices not only protect against high-temperature damage but also optimize plant health and productivity.
Author: Hebei City Agricultural Technology Promotion Center
Hollow Type LED Operating Lamp
The hollow type LED OT lamp is designed at this year, this series of lamp outlook is much simple also for the specification, so the hollow type surgical lamp price is most favorable. this series of LED operation shadowless lamp color rendering index can reach above 97, very close to the natural light (natural light color rendering index of 100) of the approximate sunlight color rendering, make the doctor at a very clear area and surgery site ( including vascular tissue and nerve tract) color, can clearly identify the organizational structure of the operation field.
Hollow Type LED Operating Lamp,LED Operating Theatre Light,LED Operating Room Light,LED Surgery Room Light
Shandong Lewin Medical Equipment Co., Ltd. , https://www.lewinmed.com