Yellow leaves may not be sick

Physiological diseases are an old problem, but they are also difficult and doubtful that vegetable growers can't overcome. With the warming of the weather and the increase of temperature, vegetables often cause physiological problems due to watering, fertilization, and improper use of medicines. Recently, many vegetable farmers generally reflect the serious problems of the current physiological diseases of vegetables, such as vegetable leaf and yellow leaf, premature aging and hormonal poisoning, leggy and convulsions, wilting and so on. For these physiological diseases, there are still many vegetable farmers who mistakenly believe that the disease is invasive and cannot be prevented and treated. As a result, the output of vegetables is reduced and the benefits are low.

Event One: The vegetable farmer Master Yin has planted two greenhouse tomatoes this year. Due to the recent high temperature, Master Yin sprinkled mud on the shed film to cool it. By noon, Master Yin saw a curling phenomenon on many tomato leaves in the shed.遂 遂 遂 遂 遂 遂 遂 遂 遂 遂 遂 遂 遂 遂 遂. What he did not expect was that there was a lot of curling in tomatoes after watering.

Event Two: Master Shaw planted a shed of tomatoes this year. Due to the well-ventilated sheds, coupled with the recent high temperature and large evaporation, the soil in the shed was quickly deprived of water. Master Shao had to carry out frequent watering. In order to meet the water evaporated by the plants, Master Shao also specifically increased the amount of water. But soon the tomatoes began to appear with a large number of leaf curls and accompanied by yellowing from the bottom.

It is not difficult to see from the above two events that after water shortage in the plants, the leaves self-regulate, and the leaves are rolled up to reduce the transpiration of water and close the stomata. Due to the lack of moisture, some nutrient elements are also insufficiently supplied, resulting in the lack of yellowing of the leaves. The phenomenon of curling and yellow leaves of vegetables is ultimately caused by root injury. The root cause of the injury was caused by the improper watering of the vegetable farmers. As the temperature rises, both the plant and the soil evaporation in the shed are greatly increased, and the water needs to be replenished in time. How can watering be performed correctly without causing root injury?

First of all, accurately grasp the watering time, high temperature watering at noon.

In the incident, the Yin master looked at lowering the temperature in the shed, but did not take into account the high temperature at noon. Suddenly, watering would cause the ground temperature to dip. It would inevitably damage the root system of the tomatoes, especially root hairs that absorb mainly. At present, it is close to midsummer, and the temperature in the shed is 30°C or even higher. The soil temperature is also kept above 20°C. The well water temperature is around 14°C. The huge temperature difference will cause the root hair cells to rupture and cause the root hairs to die. .

Therefore, sudden watering should be avoided during the noon time. It should be done when the temperature is low in the morning and evening. At this time, the ground temperature is about 15°C, which is suitable for watering. If it is in the midday shed that the evaporation of tomatoes is caused by high temperature and high evaporation, sprayer spray can be used.

Second, accurately grasp the amount of water, not excessive watering.

In the second incident, Master Shao blindly increased the amount of water when he was not able to determine the amount of water. Excessive moisture caused root anaerobic rot, which reduced the absorption of water and nutrients by the plant, resulting in leaf rolling and yellowing. Case. It is understood that Master Shao's watering is not judged based on the comprehensive sensation of the soil, but watering when the surface is dry, which will certainly lead to excessive soil moisture.

Observing the soil moisture should be selected at a distance of 10 cm from the surface, where the root system is the largest, which is the key to the determination of root absorption. To ensure that the soil is held in clumps and spread out in the ground, the range of soil relative humidity that is most suitable for vegetable roots to absorb is 70% to 85%.

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