Prevention and treatment of magnesium deficiency in Pepper with Leaf Yellow but main vein Green Fruit

Hot peppers are often deficient in magnesium during the fruiting period. Pepper leaves yellowed along both sides of the main vein and gradually expanded to the whole leaf, but the main vein and lateral veins remained green. Magnesium deficiency in sweet pepper often begins at the tip of the leaf and gradually extends to the mesophyll on both sides of the vein. The more fruit on a pepper plant, the more serious the magnesium deficiency. Once magnesium deficiency, photosynthesis decreases, the fruit is small and the yield is low. Magnesium deficiency in pepper is mainly harmful to leaves, resulting in a serious reduction in pepper production, so how to prevent and control magnesium deficiency in pepper?

Magnesium deficiency in hot pepper

Causes of magnesium deficiency in hot pepper:

Insufficient supply of magnesium in ① soil: insufficient supply of magnesium in soil is the main cause of magnesium deficiency in hot pepper. Southeast China, warm and rainy, with strong leaching, is an area prone to magnesium deficiency. The factors affecting the content of available magnesium in soil are as follows:

First, the degree of soil weathering, different soil parent material and weathering degree, magnesium content is also different, red soil weathering degree is high, mineral decomposition is more thorough, generally contains little magnesium. Purple soil has low weathering degree and high magnesium content. The vegetable base of red loam in the south of the Yangtze River in China is easy to lack magnesium.

Second, the soil texture, strong sandy soil magnesium is easy to leach, the content is low, often can not meet the needs of pepper growth. The coarse magnesium-deficient soils are mainly distributed in river valleys and hilly areas.

Third, the soil is acidic and alkaline, and the content of soil available magnesium decreases with the increase of soil acidity, because the soil with strong acidity is easy to leach.

② climatic conditions: the impact of climate on magnesium deficiency has two aspects, one is rainy, the other is drought and strong light. Heavy rain leads to the loss of magnesium, and this effect is regional, such as the distribution of magnesium-deficient soils in the south. Magnesium deficiency induced by drought and strong light is a small regional effect, such as chili peppers which are fully exposed to sunlight at the edge of the border tend to be more frequent and recurrent than those who are in the shade of each other. Drought reduced the absorption of magnesium by hot pepper. Strong light in summer can aggravate magnesium deficiency, which may be that strong light destroys chlorophyll and accelerates leaf chlorosis.

Improper fertilization of ③: excessive application of potassium fertilizer and ammonium nitrogen fertilizer will induce magnesium deficiency, because excessive potassium and ammonium ions destroy the nutrient balance and inhibit the absorption of magnesium by pepper.

Prevention and control measures of magnesium deficiency in hot pepper:

First, timely irrigation: keep the soil moist and reduce the effect of high concentration of soil salt on magnesium absorption; apply magnesium sulfate and other magnesium fertilizer, use about 10 to 20 kilograms per mu. For some acidic soils, it is best to use magnesium lime, about 50 kilograms per mu, and control the amount of nitrogen and potassium fertilizer. For the soils with poor magnesium supply capacity, it is necessary to prevent the effect of excessive nitrogen and potassium fertilizer on magnesium absorption. It is best to apply a small amount of fertilizer for many times. Spray with 1%-2% magnesium sulfate solution before symptom intensification, once every 5-7 days for a total of 3-5 times.

Second, the application of magnesium fertilizer: magnesium deficiency caused by insufficient magnesium supply in the soil can be supplemented by magnesium fertilizer, generally using magnesium sulfate and other fertilizers, using about 2-4 kg per mu (according to available magnesium). For some acidic soils, it is best to use magnesium lime (lime fired from dolomite) 50kg to 100kg, which can not only supply magnesium, but also improve soil acidity. Many chemical fertilizers, such as calcium magnesium phosphate fertilizer, contain high magnesium, which can be selected according to local soil conditions and fertilization conditions. According to some reports, the combined application of phosphate fertilizer and magnesium fertilizer is helpful to the absorption of magnesium.

Foliar magnesium supplementation should be used to correct magnesium deficiency caused by root absorption disturbance. Generally, 1%-2% magnesium sulfate solution is sprayed before symptom intensification, once every 5-7 days, for 3-5 times. Magnesium nitrate can also be sprayed.

Third, control the amount of nitrogen and potassium fertilizer: for the soil with poor magnesium supply capacity, it is necessary to prevent the effect of excessive nitrogen and potassium fertilizer on magnesium absorption. Especially greenhouse chili peppers. Often excessive fertilization and no Rain Water leaching lead to the accumulation of nutrients in the root layer and inhibit the absorption of magnesium. Therefore, it is best to apply nitrogen and potash fertilizer in the greenhouse for many times.