Functions of Essential Nutrient Elements in Garlic and Detailed Explanation of Deficiency Symptoms

Garlic prefers loose soil rich in humus, has strong adaptability to soil pH, and grows well under slightly alkaline conditions. Among the different growth stages of garlic, the demand for nitrogen is the highest, followed by potassium, calcium, phosphorus, and magnesium. For every 1000 kg of fresh garlic produced, it needs to absorb 4.5-5.0 kg of nitrogen, 1.1-1.3 kg of phosphorus, and 4.1-4.7 kg of potassium, with a ratio of about 1:0.25-0.9.

The root system of garlic is a string-like fleshy root system, mainly distributed within the 5-25 cm plow layer, and it belongs to shallow-rooted vegetables. Garlic is relatively sensitive to water and fertilizer, showing the characteristics of preferring moisture, preferring fertilizer, and tolerating fertilizer. Garlic has few root hairs, and they are thin and weak, so the root absorption capacity is relatively poor. Therefore, fertilizer and water management need to be strengthened during the growth period.

Nitrogen is one of the most important nutrient elements in garlic nutrient management. Because it is an important component of proteins, and also a component of nucleic acids, nucleoproteins, chlorophyll, and many enzymes and hormones, it is the most important limiting factor for plant growth and development. When nitrogen is deficient, both aboveground and root growth are significantly inhibited. Nitrogen deficiency has the greatest impact on leaf development: leaves are small and upright, with a small angle to the stem, and the leaf color is pale green, turning pale yellow in severe cases. Chlorotic leaves have a uniform color, and generally no spots or mottling appear.

A normal supply of phosphorus is beneficial for cell division and proliferation, and promotes root extension and aboveground growth and development. Phosphorus can strengthen photosynthesis and the synthesis and transport of carbohydrates.

It promotes nitrogen metabolism and improves the adaptability of vegetables to the external environment. Phosphorus can improve the drought resistance, cold resistance, and disease resistance of vegetables. In phosphorus-deficient plants, the leaves are small, and the leaf color is dark green or grayish green, lacking luster. Plant growth is delayed, and the plants are short, thin, and upright, with underdeveloped root systems, delayed maturity, and smaller fruits.

Potassium can promote photosynthesis, and potassium has the ability to enhance plant stress resistance, drought resistance, and lodging resistance. When potassium is deficient, symptoms first appear on old leaves and then gradually spread to new leaves. The old leaves and leaf margins first turn yellow, then brown, and scorch as if burned. When garlic is deficient in potassium, starting from the 6-7 leaf stage, white spots appear on the peripheral parts of old leaves, the leaves curve toward the back side, and the white spots disappear as the old leaves die.

Calcium is an important component of the cell wall. Calcium can promote the absorption of other nutrient elements.

When garlic is deficient in calcium, necrotic spots appear on the leaves. As the necrotic spots expand, the leaves bend downward, and the leaf tips die quickly. When calcium deficiency symptoms appear, foliar fertilizer containing relatively more calcium and with relatively high absorption and utilization efficiency should be sprayed in time.

Calcium-deficient areas generally occur on fruits and old leaves, such as blossom-end rot in tomatoes and tipburn in cabbage.

Magnesium is the central element of the chlorophyll molecule. Magnesium is an activator of many enzymes and participates in metabolic processes. Magnesium can promote vitamin synthesis. When garlic is deficient in magnesium, the leaves become chlorotic, first appearing at the base of old leaves and gradually developing toward the leaf tip, and the leaves eventually turn yellow and die.

In vegetable production, attention is often paid to the application of nitrogen fertilizer and potassium fertilizer, while the supplementation of magnesium fertilizer is neglected. Due to element absorption antagonism, vegetable leaves often show magnesium deficiency symptoms of interveinal chlorosis.

Sulfur is a structural element of proteins. Sulfur is a key element in a series of volatile substances produced by crops. Plants appear pale green and yellow-green. Young leaves are more obviously affected than old leaves. Plants are short, and leaves are small.

Boron participates in the transport of photosynthetic assimilates. Boron is one of the key elements for plant reproductive growth. When garlic is deficient in boron, new leaves become yellowed, and in severe cases the leaves die, plant growth stagnates, and small brown cracks can be seen when the leaf sheaths are dissected. When these symptoms appear, boron-containing foliar fertilizer can be sprayed.

Iron: an essential element for chlorophyll; participates in electron transport.

Zinc: an essential element for chlorophyll; participates in auxin synthesis;

Manganese: participates in photosynthesis; participates in the activities of enzyme systems.

Copper: a component of chloroplasts; participates in the activities of enzyme systems.

Boron: participates in the transport of assimilates; is one of the key elements for plant reproductive growth.

Molybdenum: participates in nitrogen metabolism;

Chlorine: participates in photosynthesis; regulates osmotic pressure.

Differences between deficiencies of iron, manganese, copper, and zinc:

Iron deficiency: new leaves become yellow-white, heart leaves are often albino, and interveinal chlorosis is distinct.

Manganese deficiency: young tender leaves become chlorotic and yellow, and in severe cases small dark brown spots appear, and necrosis and perforation may occur.

Copper deficiency: leaf tips turn white and curl, tillering increases, lateral buds increase, and root growth stops.

Zinc deficiency: plants are short, internodes are short and clustered, little leaf disease occurs, and interveinal chlorosis first appears near the midrib of new leaves.

Farmers can make a diagnosis based on the specific performance of garlic and supplement the corresponding fertilizer to improve the yield and quality of garlic.