Cause Analysis and Prevention of Ten Kinds of Yellow Leaves in Crops

1 , wet yellow

 

Due to excessive soil moisture, the soil is deprived of oxygen, making the roots difficult to breathe, the roots are absorbing water, the fertilizer is blocked, and the growth cannot be carried out normally, resulting in the yellow leaves of the new shoots of the seedlings, and the old leaves are gradually dark yellow, and then wither and die. At this time, the soil should be loosened and drained in time to control the amount of irrigation.

 

2 , drought yellow

 

Drought can cause seedlings to appear wilting. At this time, the photosynthesis is lowered, the growth is paused, the transportation of photosynthetic products is hindered by water shortage, and the organic matter in the plant is hydrolyzed in a large amount, and the breathing is enhanced, thereby consuming a large amount of organic matter. Due to the redistribution of water in the plants, the new leaves take water from the old leaves, causing the old leaves to fall off. It can be irrigated according to the dryness and wetness of the soil and the changes of the leaves, and the watering is poured through.

 

3 , dark yellow

 

The normal growth of plants requires twice the light intensity above the light compensation point. At this time, in addition to compensating for respiratory consumption, the organic matter produced by plant photosynthesis can satisfy the normal needs. If the light is insufficient, it will lead to smooth differentiation under the plant cells, the stems and branches of the seedlings are weak, and the leaves are yellowed. Precautionary measures are to increase the light in time. Greenhouse plants can be artificially filled with light, and plastic films of different colors can be selected to adjust the light quality to increase the yield, improve the quality or reduce the pests and diseases.

 

4 , insect yellow

 

In the process of seedling cultivation, it is often attacked by pests, especially pests of various food leaves and sucking mouthparts, which damage the leaves or suck the leaf juice, causing the leaves to shrink and curl, causing the leaves to appear spots and turn yellow. Should pay attention to observation, early prevention, against pests, timely and appropriate amount of symptomatic spray.

 

5 , sick yellow

 

Nursery seedlings often have some diseases, such as blight, rust, leaf spot blight, etc., which affects the survival rate of seedlings and makes plants poorly developed. Therefore, it is necessary to observe the leaves and growth of the seedlings frequently, and regularly disinfect the seedbed soil to eliminate pathogenic bacteria in the soil. It is extremely important to control the onset of the disease. Once the disease is discovered, it is necessary to prevent it in time.

 

6 , yellow

 

In addition to essential elements such as nitrogen, phosphorus and potassium, seedlings are also very sensitive to certain trace elements. When it is lacking, it will cause disturbance of physiological functions of seedlings, resulting in various symptoms of seedlings, also expressed in leaf color, such as Iron deficiency, zinc, magnesium, sulfur, manganese, etc., will lead to chlorosis and yellowing of the leaves. The cause of micronutrient deficiencies is mainly the result of long-term non-replacement or long-term single application of nitrogen fertilizer. Therefore, it is necessary to carry out the improvement of the soil on the seedbed every other year, paying attention to the application of organic fertilizer.

 

7 , fat yellow

 

Too much or too little fertilizer will have a bad effect on the seedlings. When the fertilization is too thick and too much, it will cause the plant to penetrate and transport, and the new leaves will be thick, the leaves will wrinkle without stretching, and the old leaves will yellow and not fall off. When the fertilizer is lacking, it will cause the branches to be tender, the internodes are long, and the leaves are thin and yellow.

 

Therefore, rational fertilization can improve the photosynthesis of plants. For example, nitrogen and magnesium promote branch and leaf growth, expand photosynthesis area, increase chlorophyll content, and increase photosynthetic rate. Nitrogen, calcium and zinc prolong the life of the leaves and prolong the photosynthetic time. Phosphorus, potassium and boron improve the transport and distribution of photosynthetic products.

 

In addition, rational fertilization can improve the soil and create a good living environment for plants. For example, the application of organic fertilizer can increase the agglomerate structure of the soil, not only improve the water, gas and temperature conditions of the soil, promote the growth of roots and the absorption of fertilizers, but also promote the activities of soil microorganisms, accelerate the decomposition of organic matter, and improve the nutrient. Supply status.

 

8 , acid yellow

 

The pH of the seedbed soil can affect the solubility of the mineral. In alkaline soils, iron, calcium, phosphorus, magnesium, zinc and the like are prone to form soluble compounds, thereby reducing the absorption of these elements by plants and causing yellow leaf disease. When the soil is too acidic, iron, aluminum, manganese, etc. are too much dissolved, and the plants are poisoned by excessive absorption. Therefore, controlling the pH of the soil is an important means to ensure the normal growth of the seedlings, and ammonium salts can be applied to the alkaline soil. Nitrogen can be applied to the acidic soil to adjust the pH of the soil , making it suitable for seedling growth.

 

9 , yellow medicine

 

Due to the prevention and treatment of insects and diseases, the spraying of pesticides is improper or the concentration is too large, causing phytotoxicity of the seedlings, causing the leaves to yellow and fall off. Therefore, in the use of pesticides, must be strictly in accordance with the instructions, according to a certain proportion of spraying, once the occurrence of phytotoxicity, should be washed with water as soon as possible to reduce the drug.

 

10 , cold yellow

 

Sowing in spring, due to low temperature, although below zero, but below the lower limit of normal growth of seedlings, the protoplast viscosity in plant cells is increased, cell permeability is reduced, resulting in reduced respiratory rate, absorption of water, mineral elements Slow down, the young leaves of the young shoots appear yellow and wilting. At this time, you should pay attention to cold protection.

 

 

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