Manifestations of deficiencies in plant nutrition
Individual types of garden crops, as well as their varieties, have specific, genetically determined requirements for nutrients. Plants respond to any deviation from this biological rule negatively by slowing down growth, reducing yield, deteriorating quality, reducing resistance to diseases and pests, diseases and, in extreme cases, dying. A smaller or larger deficiency or excess in the intake of a single nutrient is enough and the plant is already limited in its performance.
Fortunately, plants on fertile soils can „repair“ minor „defects“ in nutrient intake. A slight surplus or shortage will lead to good soil, which is in the so-called. old power of nutrients, face. However, once this ability is exhausted, plant nutrition disorders occur.
The greater the errors in nutrition, the more pronounced the consequences. Minor deficiencies on plants usually do not show more pronounced symptoms to the human eye during vegetation. However, they can be very well determined by chemical manorganic analysis of plants or parts thereof (eg leaves).
Greater shortcomings are reflected in the external appearance of plants with changes that do not escape the eye of the gardener.
1. Symptoms of nutrient deficiencies
An important sign of a deeper lack of nutrients in the visual assessment (so-called visual diagnostic methods) is the place of occurrence of symptoms on the outside of the plant.
If symptoms of deficiency occur in the initial period:
(a) on younger leaves, the plant lacks iron or zinc, copper or boron;
(b) on older leaves, the plant lacks either nitrogen or phosphorus, potassium or
At nitrogen deficiency (N) plants grow poorly, remain small and mature earlier, fruits are small and few. At first the leaves are light green, later even yellow, or even reddish, older leaves often fall off prematurely.
Also at phosphorus deficiency (P) plants lag behind in growth, are small and stunted. The flowers are poorly fertilized, the fruits are difficult to ripen and are acidic. Older leaves are gray-green, partly reddish and fall off prematurely. If the plants suffer from a lack of potassium (K), the water regime is disturbed, so that the leaves, or. whole plants have a withered appearance. The edges of the leaves fade to brown (first in the older ones), the leaf tips sometimes twist inwards. The shoots of the branches near the trees dry out, the fruits are small, do not taste good and are not durable.
At calcium deficiency (Ca) ceases to form root hairs and old roots turn brown, later rotting and dying. The edges of the younger leaves are faded, the older ones are dark green. In particular, stone fruits and shells suffer from glucose and cancer.
Symptoms magnesium deficiency (Mg) are very typical. First, on the older leaves, yellow spots appear between the green veins of the blade next to the dark green ones. Clusters of green chlorophyll resemble beads strung on a string. This mosaic later turns into continuous striped chlorosis (up to necrosis) in monocots and spotted in dicotyledons. In case of severe deficiency, the symptoms also appear on younger leaves.
Sulfur deficiencies (S) are similar to nitrogen. However, light green to yellow are younger leaves at first.
A typical manifestation iron deficiency (Fe) is the so-called chlorosis, ie the leaves are light green to bright yellow at the end of the shoots.
In manganese (Mn) in its absence, light yellow to dark brown spots form between the veins of the blade of the middle to upper leaves. Root growth also lags far behind. These symptoms are especially pronounced in cucumbers.
At boron deficiency (B) the tops of young shoots die off, the young leaves are often curled and brittle. At first they have a dark green to blue-green color, later they fade and die. The flowers do not form or develop. The fruit shows screaming and freckles.
Up to whitish coloring and bottling, or the curvature of the youngest leaves is a manifestation copper deficiency (Cu). Flower formation is also limited. Withering is a common symptom.
Zinc deficiency (Zn) is manifested by the lightening of the leaves (fading) between the veins on the blade of the young leaves, which remain small and twisted. It can result in infertility in trees.
Symptoms molybdenum deficiency (Mo) are similar to nitrogen. The older and middle leaves are initially blue-green, later light green to yellow. They die by browning. The plants do not bloom and stop growing. In the case of cauliflower, the so-called „Blindness“ – no flower rosette is formed.
2. Symptoms of nutrient excess
Not only insufficient intake of nutrients, but also their excessive accumulation in plants (called luxury consumption), has a negative impact on plants.
The cause is usually the mistakes we made during fertilization. Excessive intake of one or more nutrients often leads to reduced intake of others
nutrients (consequence of antagonism).
With a luxurious intake of nutrients, not only does the intensity of growth and product formation decrease, but their quality also deteriorates. Symptoms of excess nutrients on plants are manifestations of already toxic effects, which variously damage plant organs and their function.
In the gardens of small growers, the „overdose“ can most easily occur excessive nitrogen intake (N). Although the symptoms are not as pronounced as with a lack of nitrogen, its excess is manifested by too lush growth of dark green leaf mass and limited formation of flowers and fruits. The quality of harvested products is reduced mainly due to the high content of nitrates (nitrates).
WITH excess phosphorus (P) We rarely meet. Symptoms may be deficient in iron (Fe) or zinc (Zn) deficiency, which suppresses intake.
Excess potassium (K) is usually manifested in rotlins by limiting the intake of magnesium (Mg) and calcium (Ca). Direct excess calcium (Ca) is not known in plants. „However, calcification is reflected in reduced iron intake and plants suffer from chlorosis. Excess magnesium (Mg) is usually accompanied by a lack of calcium, which is manifested by the described symptoms on shoots and roots. Symptoms excess sulfur (S) are most often known in conifers as air pollution damage from atmospheric fallout near sources of combustion of products with higher sulfur content.
In microelements (trace elements), where the range between deficiency, optimum and excess in plant nutrition is very narrow, “overdose can easily cause noticeable damage to plants. In the body (B) is, for example, characterized by the yellowing of the leaf tips, which later spreads and turns into a browning of the entire leaf. Excess copper (Cu) usually shows symptoms of iron deficiency. On excess manganese (Mn) are sensitive cherries and in cucumbers the veins of older leaves turn reddish brown and dark red. Golden and orange-yellow chlorosis in tomatoes is a symptom excess molybdenum (Mo). Symptoms excess zinc (Zn) correspond to symptoms of either iron or manganese deficiency. In contrast, chlorosis of the leaf edges, browning and death, for example in currants, are a symptom excess chlorine (WHOSE).
3. Other negative effects of defects in the nutrition of garden crops
Proper balanced nutrition of plants increases their resistance (resistance) to diseases, pests and extreme climatic fluctuations. Plants that suffer from a deficiency or excess of certain nutrients have less resistance to attack at the same infection pressure. For example, an excess of nitrogen (N) in plants allows stronger infestation of plants by powdery mildew, a lack of phosphorus (P) and potassium (K) results in less resistance to rust. In the absence of potassium, the sugar content of the leaves increases, which promotes aphid infestation. In crops exposed to frost, insufficient potassium content results in less resistance. Plants that have not been sufficiently fed with phosphorus in their youth are less tolerant of cold. Nutritional deficiencies that result in insufficient root development (such as calcium) increase the risk of drying out because the plant has not grown into deeper, moist soil layers. Also the lack of potassium in the tissues of plants results in a deterioration of water management, ie. less resistance to drought.
Deficiencies in the quality of garden crop products have their origin very often in unbalanced plant nutrition. Today, the most frequently discussed problem among growers is the excessive content of nitrates in garden products. The following are the maximum permissible values for the nitrate content of vegetables under the current guidelines of the Ministry of Health and the Ministry of Agriculture. These values will be gradually refined in the coming years, and we therefore recommend following the relevant updated guidelines. Harmful accumulation of nitrates in plants occurs if the nitrogen intake is not balanced by the intake of other nutrients (or even light, heat, water). In this so-called Due to the luxury consumption of nitrogen, its nitrate (nitrate) form cannot be processed into desirable and useful nitrogenous substances (proteins, etc.), so nitrate nitrogen is actually unprocessed and unincorporated due to nutritional defects. Therefore, the principle is that the better we can feed plants (so that they do not suffer from a lack of any of the nutrients), the more nitrogen the plant can absorb without accumulating nitrates, and the higher and better yield we can achieve.
Excess nitrogen and especially lack of potassium, but also an excess of chlorine or calcium, worsen the consumption quality, but also the storability of potatoes. Sufficient phosphorus guarantees the maturity of tubers. Lack of calcium worsens the quality of apples (horseradish). There are a number of other more or less adverse impacts caused by a lack or excess of nutrients, and therefore the growing interest of gardeners in the proper nutrition of garden crops is entirely appropriate.
Maximum permissible nitrate contents in mg NaNO3 per 1 kg
Field salad, spinach
Early cabbage, field brussels sprouts
Cabbage early, late
Garlic with topping, dry
Green onions, dry, leeks