1 The role of calcium Calcium is an essential nutrient for apples and an important component of the cell wall. When calcium is deficient, the cells cannot divide normally. In severe cases, the growth point is necrotic, and physiological diseases are highly prone to occur. Calcium not only inhibits fungal attack, reduces the infection rate of the disease, but also reduces the toxic effects of certain ions in the soil.
2 Apple calcium deficiency symptoms Calcium is easy to form insoluble calcium salts in fruit trees and is fixed, which is a nutrient element that cannot be transferred and reused. Therefore, the symptoms of calcium deficiency in apples are first manifested in the new tissue: a root symptom. The formation of multi-branched short and thick root groups, the masses called the "broom root", and the root tip died in severe cases. 2 leaf symptoms. As a result, the new shoots stopped growing prematurely, the young leaves were curled, the edges of the leaves were yellow, and the midribs of the leaves had necrotic spots. 3 fruit symptoms. When the fruit is nearing maturity (early September), the disease appears to expand and spread over time. The surface of the fruit appears small brown necrotic spots, the flesh shrinks into a sponge, and the heart is water-stained, forming bitter pox disease. , corked spot disease and water heart disease, especially the physiological diseases caused by the lack of calcium in bagged apples are more serious.
3 Calcium supplementation technology The experimental investigation found that apples with acidity (pH <5.6) and low soil organic matter content have serious physiological diseases caused by calcium deficiency. Therefore, it is necessary to adapt to local conditions, in the process of apple growth, targeted implementation of comprehensive calcium technology measures.
3.1 Adjusting soil pH and increasing soil exchangeable calcium content Soil pH is closely related to the availability of soil calcium. In general, the acidity of orchard soil is insufficient, and the pH value of orchard soil must be adjusted to a suitable range. The reason for the strong acidity of the orchard soil is mainly caused by unreasonable fertilization, such as the physiologically acidic fertilizers such as potassium sulfate, potassium chloride and ammonium chloride, which are commonly used in production, and the cations (NH4+) after application of soil. , K+) is absorbed by the fruit tree, leaving the acid root. In addition, some long-term use of superphosphates in orchards contains a large amount of free acid, which will increase the acidity of the soil year by year. To solve the problem of soil acidity: 1 replace the fertilizer. Nitrogen fertilizer is mainly urea, phosphate fertilizer is changed to calcium magnesium phosphate fertilizer, potassium fertilizer is potassium sulfate; 2 calcium supplementation. Generally, 60-70 kg of calcium carbonate is applied per 667 square meters, which has a good effect of improving soil acidity, thereby directly increasing the content of soil exchangeable calcium. The soil pH can be adjusted to 6.5--7.5 for 3 to 3 years; 3 control the nitrogen fertilizer. Excessive nitrogen fertilizer will affect the absorption of calcium.
3.2 Adding organic fertilizer to improve the soil's retention of calcium. Adding organic fertilizer is an effective technical measure to improve soil organic matter content, improve soil physical and chemical properties, and enhance soil's ability to retain calcium. According to the survey, in the orchards where the organic matter content of the soil is more than 1.3%, the apple deficiency is rare. This is because the soil organic matter content is high, the soil aggregate structure is good, and the soil's ability to retain calcium is increased. At the same time, the organic fertilizer is generally neutral to alkali, which can reduce the activity of cationic iron and aluminum in the soil, reduce the influence of cations on the activity of calcium in the soil, and ensure the absorption of calcium by the root; then the organic fertilizer contains a lot of trace elements. , can continue to provide calcium and micro-nutrient nutrition for apples. Therefore, the orchard should increase the amount of organic fertilizer, generally reaching more than 4000kg per 667 square meters per year.
3.3 Foliar spray fertilizer, the whole process of calcium supplementation Research shows that the young fruit period is the most prosperous period for apples to absorb calcium. Due to the poor mobility of calcium, it is necessary to implement the whole process of calcium supplementation. The time should start from two weeks after the apple falls, and the leaf surface sprays 350 times liquid amino acid calcium or 800 times liquid ammonia calcium treasure liquid fertilizer, spraying every 12-14 days. Second, even spray 2 - 3 times. For bagging apples, spray more than 2 times of foliar calcium fertilizer before bagging to ensure sufficient calcium nutrition in young fruit stage; spray 40 times before 40--50 days before fruit picking; long-term storage after fruit picking Soak the fruit with 4% calcium chloride solution for 3 minutes, wash it with water and then store it. It can prevent the disease during storage, prolong the storage period and increase the economic benefit.
2 Apple calcium deficiency symptoms Calcium is easy to form insoluble calcium salts in fruit trees and is fixed, which is a nutrient element that cannot be transferred and reused. Therefore, the symptoms of calcium deficiency in apples are first manifested in the new tissue: a root symptom. The formation of multi-branched short and thick root groups, the masses called the "broom root", and the root tip died in severe cases. 2 leaf symptoms. As a result, the new shoots stopped growing prematurely, the young leaves were curled, the edges of the leaves were yellow, and the midribs of the leaves had necrotic spots. 3 fruit symptoms. When the fruit is nearing maturity (early September), the disease appears to expand and spread over time. The surface of the fruit appears small brown necrotic spots, the flesh shrinks into a sponge, and the heart is water-stained, forming bitter pox disease. , corked spot disease and water heart disease, especially the physiological diseases caused by the lack of calcium in bagged apples are more serious.
3 Calcium supplementation technology The experimental investigation found that apples with acidity (pH <5.6) and low soil organic matter content have serious physiological diseases caused by calcium deficiency. Therefore, it is necessary to adapt to local conditions, in the process of apple growth, targeted implementation of comprehensive calcium technology measures.
3.1 Adjusting soil pH and increasing soil exchangeable calcium content Soil pH is closely related to the availability of soil calcium. In general, the acidity of orchard soil is insufficient, and the pH value of orchard soil must be adjusted to a suitable range. The reason for the strong acidity of the orchard soil is mainly caused by unreasonable fertilization, such as the physiologically acidic fertilizers such as potassium sulfate, potassium chloride and ammonium chloride, which are commonly used in production, and the cations (NH4+) after application of soil. , K+) is absorbed by the fruit tree, leaving the acid root. In addition, some long-term use of superphosphates in orchards contains a large amount of free acid, which will increase the acidity of the soil year by year. To solve the problem of soil acidity: 1 replace the fertilizer. Nitrogen fertilizer is mainly urea, phosphate fertilizer is changed to calcium magnesium phosphate fertilizer, potassium fertilizer is potassium sulfate; 2 calcium supplementation. Generally, 60-70 kg of calcium carbonate is applied per 667 square meters, which has a good effect of improving soil acidity, thereby directly increasing the content of soil exchangeable calcium. The soil pH can be adjusted to 6.5--7.5 for 3 to 3 years; 3 control the nitrogen fertilizer. Excessive nitrogen fertilizer will affect the absorption of calcium.
3.2 Adding organic fertilizer to improve the soil's retention of calcium. Adding organic fertilizer is an effective technical measure to improve soil organic matter content, improve soil physical and chemical properties, and enhance soil's ability to retain calcium. According to the survey, in the orchards where the organic matter content of the soil is more than 1.3%, the apple deficiency is rare. This is because the soil organic matter content is high, the soil aggregate structure is good, and the soil's ability to retain calcium is increased. At the same time, the organic fertilizer is generally neutral to alkali, which can reduce the activity of cationic iron and aluminum in the soil, reduce the influence of cations on the activity of calcium in the soil, and ensure the absorption of calcium by the root; then the organic fertilizer contains a lot of trace elements. , can continue to provide calcium and micro-nutrient nutrition for apples. Therefore, the orchard should increase the amount of organic fertilizer, generally reaching more than 4000kg per 667 square meters per year.
3.3 Foliar spray fertilizer, the whole process of calcium supplementation Research shows that the young fruit period is the most prosperous period for apples to absorb calcium. Due to the poor mobility of calcium, it is necessary to implement the whole process of calcium supplementation. The time should start from two weeks after the apple falls, and the leaf surface sprays 350 times liquid amino acid calcium or 800 times liquid ammonia calcium treasure liquid fertilizer, spraying every 12-14 days. Second, even spray 2 - 3 times. For bagging apples, spray more than 2 times of foliar calcium fertilizer before bagging to ensure sufficient calcium nutrition in young fruit stage; spray 40 times before 40--50 days before fruit picking; long-term storage after fruit picking Soak the fruit with 4% calcium chloride solution for 3 minutes, wash it with water and then store it. It can prevent the disease during storage, prolong the storage period and increase the economic benefit.
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