At present, it is a critical period for the growth of autumn tomatoes. Water and fertilizer management directly affect the growth of tomatoes in the management process. Professor Zhang Enhui of the College of Horticulture, Northwest A&F University, reminds farmers to pay attention to the symptoms of tomato deficiency and timely prevention and control to ensure production and increase income.
Calcium deficiency
Calcium deficiency disease begins in young fruit and begins as a dark brown spot with immersion, gradually developing into a brown or black necrotic area. Can be extended to the interior of the fruit, disease early reddening, is a typical physiological disease, easily lead to umbilical rot. Preventive measures: Use organic fertilizer as base fertilizer and apply a certain amount of superphosphate to prevent calcium deficiency in the soil. Second, it is necessary to plough the land deep and use plastic film to cover cultivation to keep the soil moisture relatively stable and reduce the loss of calcium in the soil. Thirdly, the result period guarantees a balanced supply of moisture, prevents sudden changes in moisture, timely watering at high temperatures and drought, and timely drainage in the rainy season to ensure the normal function of the root system. Fourth, nitrogen fertilizer is applied stably in the early stage of growth to avoid overgrowth of nutrients. In addition, the fruit of umbilical rot should be removed in a timely manner in order to reduce the consumption of nutrients in the plant and ensure the growth of healthy fruits.
Potassium deficiency
More potassium is required for tomato growth. When potassium is lacking, the leaf tissue between the main veins is chlorotic, and the leaves are curled and reddish green. In severe cases, burns occur along the leaf margins. Potassium deficiency reduces the acid content of the fruit and causes the internal fading of the fruit. In the middle and late stages of tomato growth, even if the content of potassium in the soil is not low, due to the decreased root absorption capacity, it cannot provide enough potassium to supply fruit development and plant growth, and when the fruit matures, it still shows symptoms of potassium deficiency. When the supply of potassium is insufficient, the development of the fruit is at the expense of damage to the leaves. Usually, when the fruit is between 3 ears and 4 ears, the old leaves are prone to symptoms of potassium deficiency. Potassium fertilizer should be applied during cultivation. Potassium fertilizer is volatile and easy to leaching. The combination of base application, top dressing and foliar spray should be adopted to ensure the supply of potassium in the middle and later stages.
Phosphorus deficiency
Phosphorus deficiency at seedling stage will make the plant grow slowly and the leaves will become purple. Low temperature, drought and other reasons also hinder the ability of root absorption, and there are symptoms of phosphorus deficiency. Phosphorus is less mobile in soil and requires a large amount of phosphorus at the seedling stage. It should be applied at the end and deep. Phosphorus is easily fixed by soil colloids, so the application of phosphate fertilizer can be mixed with the decomposed organic fertilizer or concentrated application of the ditch. The granular phosphorus fertilizer can be used to reduce the contact surface with the soil, and the foliar spray can be used during the growth period. Phosphorus, improve the utilization of phosphate fertilizer.
Iron deficiency
Iron is a trace element, but plays an important role in plant growth and development, iron deficiency can make the leaves chlorosis, alkaline soil will hinder the iron absorption of plants, should be applied with iron fertilizer, but not excessive. Commonly used ferrous sulfate, base fertilizer 2 kg / acre to 7.5 kg / acre, foliar spray 0.2% to 1% of the aqueous solution.
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