The central part of the cucumber leaves is raised, and the edge is turned backwards, showing a parachute.
The emergence of parachute leaves throughout the plant is a process: the new leaf near the growing point is initially yellowed, then the leaf margins are yellow and the yellowing part gradually withers. Then the center part of the blade gradually rises, and the surrounding area rolls down into a parachute shape. In severe cases, the symptoms persisted to the parietal lobe until the growth point was torn down, but symptoms were most pronounced in the median lobe.
1 When the symptoms are mild, the later leaves are normal and there is no problem in growth and development;
2 In the greenhouse cultivation, the symptoms were significant when the median lobes were expanded.
Prone to conditions:
The emergence of parachute leaves is a symptom of plant calcium deficiency. Calcium deficiency may have different causes:
(1) Calcium deficiency during periods of low temperature and low illumination: In some greenhouses with poor thermal insulation performance, the temperature continues to drop, and the ground temperature can easily fall below the boundary temperature, causing the absorption of calcium to be hindered: First, the ability of the low ground temperature to absorb calcium in the root system is reduced; Can not or dare to water, the soil solution is continuously concentrated, the antagonism of ions inhibits the absorption of calcium; Third, can not or rarely release the wind, the transpiration of plants is hindered, the calcium absorbed by the root can not or can not be transported to the growth Point part. Calcium deficiency causes yellowing of the leaf tip, which in turn causes yellowing of the leaf margin. After the yellowish part of the tissue has shriveled and dried, the growth of this part has been restricted, and the growth of the central part is still underway, thus forming a parachute leaf.
(2) Deficiency of calcium in high temperature period: After entering April, due to the high temperature around noon around the shed, if the ventilation is poor for a long time, the transpiration of the plant is hindered, the operation of calcium in the plant body will be limited, and parachute will also occur. leaf.
When evaporation is inhibited, symptoms of calcium deficiency appear at the growing point and the leaf margins. In the dark and rainy days, when the awning window is closed in the daytime, when it is hot and the ventilation is insufficient, the symptom of evaporation is suppressed.
(1) For greenhouses used in deep winter seasons, winter greenhouses with good daylighting and insulation properties must be used. The minimum indoor air temperature should not be lower than 9.5Â°C in principle. Even if the minimum air temperature is 8Â°C, its duration is also Cannot exceed 3 days. Only in such excellent solar greenhouses can the normal growth and flowering of the cucumber be guaranteed, and management measures can be implemented properly.
(2) Although the solar greenhouse used for cucumber production cannot set or open the lower air outlet, it must be provided with an upper air outlet that can ensure normal ventilation. Greenhouses and greenhouses must be ventilated in a timely manner during hot seasons.
Once the parachute leaf is difficult to recover, it can be relieved by spraying calcium source 2000 or calcium chloride.
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