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Mineral Starvation Of Fruit Plants
Mineral Starvation Of Fruit Plants

Video: Mineral Starvation Of Fruit Plants

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Video: Fruit tree seedlings in Ethiopia 2023, January

Read the first part of the article: Elements of mineral nutrition of plants


Phosphorus starvation in plants is quite rare, and it is expressed in a delay in root growth and plant growth in height. Shoots become short and thin, they practically do not grow.

The leaves also become uncharacteristic - they are narrow and elongated. The lower leaves, among other things, take on a strange bluish-green color, sometimes even with a bronze tint. Flowers and fruits fall off quite a lot.

In gooseberries, the lack of phosphorus changes the purple color of the leaves to reddish-purple, and because of this, small brown spots or a dark bronze rim appear on the leaves of the currant. The old leaves of the strawberry are purple-bronze, the veins on the underside of the leaf are purple, the drying leaves are dark, almost black in color. In stone fruit crops, a lack of phosphorus leads to the fact that the fruits acquire a greenish tint, and the pulp becomes sour.

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The lack of potassium, first of all, appears on the leaves. For example, in apple, cherry, plum, red currant and gooseberry, they acquire a bluish-green color, in a pear - dark brown, and in black currant - a red-purple hue, in addition, in spring, and sometimes in summer, wrinkles appear on the leaves. …

However, the most characteristic sign of potassium deficiency is the appearance of a rim of drying tissue along the edges of the leaf blade of the lower leaves. By the way, even if young leaves are of normal color and size, one cannot confidently assert the sufficiency of potassium, a marginal burn usually appears on more mature leaves.

The manifestation of potassium starvation on cherry and plum leaves occurs gradually, the edges of the leaves are at first dark green, then they become brown. In raspberries, the leaves curl quite strongly inward, this leads to the effect of gray foliage and causes a decrease in the quality of, for example, planting material.

Often on the plant, you can see a fairly large number of leaves with ragged edges, resembling insect damage. Due to the lack of potassium, gooseberry leaves acquire a purple hue, and the shoots begin to die off by the end of the season. As for the fruits harvested from such plants, they are of poor quality and poorly stored.

Very often, trees grow normally during almost the entire growing season, and signs of starvation appear only in summer. In apple trees, this leads to the fact that the fruits do not ripen at the same time and have a pale color, and leaf fall is greatly delayed. In strawberries, a red border appears at the edges of the leaves, which then turns brown, and with an excess of potassium and a simultaneous lack of magnesium, it develops gray fruit rot. Plum is a good indicator of potassium deficiency.

However, it should be noted that, in practice, very often there is a lack of not one, but a number of nutrients, and their signs of deficiency are therefore combined. For example, with a simultaneous deficiency of phosphorus and potassium, plants do not show special signs of starvation, but they grow poorly. With a large lack of these elements, a purple color of the lower part of the shoots and cuttings of leaves may appear.

With a lack of nitrogen and phosphorus, the leaves acquire a light green color, grow at an acute angle to the shoot and become tough, and the plants often do not bear fruit. With a significant lack of nitrogen, phosphorus and potassium, plants grow poorly, bear fruit rather poorly and have few seeds.

Physiological effect of mineral deficiency

Visible morphological effects or symptoms of mineral deficiency are the result of changes in various internal biochemical or physiological processes. However, due to the complex relationships between them, it can be difficult to determine how the lack of a particular element causes the observed effects. For example, a lack of nitrogen can inhibit growth due to a poorer nitrogen supply for the biosynthesis of new protoplasm.

But at the same time, the rate of synthesis of enzymes and chlorophyll decreases, and the photosynthesizing surface decreases. This causes a weakening of photosynthesis, impairing the supply of growth processes with carbohydrates. As a result, it is possible to further reduce the rate of absorption of both minerals and nitrogen. Often, one element performs several functions in a plant, so it is not easy to determine the violation of which particular function or combination of functions causes the appearance of visible symptoms.

For example, manganese, in addition to certain enzyme systems, is required for the synthesis of chlorophyll. Its deficiency causes some functional disorders. Lack of nitrogen usually causes a marked decrease in photosynthesis, but the effect of lack of other elements is not so clear.

Deficiency of the same elements often affects photosynthesis and respiration in different ways. As for potassium, a significant lack of it slows down photosynthesis and increases respiration and thereby reduces the amount of carbohydrates, which, among other things, can be used for growth. Sometimes, due to this, their very movement is suppressed, and due to the low content of storage carbohydrates, the formation of seeds is also reduced.

It is widely known that different plant species differ in their ability to accumulate elements. For example, dogwood and oak leaves contain twice as much calcium as pine leaves growing on the same soil. Hence the different reactions of various plant species to the deficiency of minerals.

Measures to combat mineral deficiencies

Improvement of the currently existing methods of diagnosing a deficiency of mineral elements and recognizing its causes in the practice of gardening contributed to the development of methods for its prevention. Attempts to improve them were made in several directions, including the application of fertilizers, the selection of forms that utilize the available elements most efficiently, and sometimes the use of nitrogen-fixing species as undergrowth to improve the supply of plants with nitrogen.

The most common method is the use of fertilizers, it has long been the generally accepted way to quantitatively and qualitatively improve the growth of fruit trees and shrubs. Fertilization has been practiced for many years, as the high cost of land and its cultivation and the relatively high prices for products have made fertilizers extremely profitable.

Large areas of the garden are often fertilized from airplanes, and sludge from wastewater treatment is also added. Sometimes foliage and branches are sprayed with urea or other nutrients. The introduction of essential nutrients in this manner is generally viewed as a supplement rather than a substitute for soil dressing.

But, despite this, it should not be discounted, since applying, for example, nitrogen and potassium to the soil and through the foliage is often equally effective. Here, the choice of method should be determined by economic considerations, since the nutrients that fall on the tree bark during the spraying are absorbed through the cracks and crevices, as well as the wounds from pruning. It should also be emphasized that in horticulture, fertilizers can have a variety of effects on both the quality and quantity of products, be they flowers, fruits or ornamental shrubs.

However, an abundant application of nitrogen increases the yield, but often worsens the color of, for example, apples and delays their ripening. In deciduous fruits, fertilization also affects aroma and keeping quality. The most in-depth studies of the effect of fertilizers on the quality of fruits were carried out on citrus crops. Apparently, it is necessary to apply fertilizers in such a way as to maintain the optimal ratio between the quality of the fruits and their yield.

In "forest" soils, nitrogen deficiency is very often observed, and in some areas there is a significant deficiency of phosphorus and potassium. These elements are the most important for the mineral nutrition of fruit trees. Among other things, fruit and ornamental trees are often deficient in trace elements such as iron, zinc, copper and boron, especially on rich soils, lime or sandy soils.

In such soils, microelements are best added in the form of chelates. As for the lack of nitrogen, in agriculture, this problem is being fought by using nitrogen-fixing fruit crops, or by increasing the content of organic matter by growing cover crops. However, there were cases when the grass cover affected the apple harvest, reducing it.

There are great differences between plants of the same species and between different species in their ability to absorb and use minerals. It follows from this that it is necessary to pay more attention to the selection of genotypes with favorable physiological characteristics, in particular, with the effective use of mineral nutrients.

As for the fertilization itself, the maximum results from its application can be obtained only in the absence of other significantly limiting factors. For example, summer droughts can limit growth rates so severely that fertilization will only slightly increase growth or not affect it at all. Also, the effectiveness of fertilization can be dramatically reduced by waterlogged soils, attacks by nematodes or, for example, damage by pathogenic fungi.

Also, foliar loss caused by insects or fungi can reduce photosynthesis to the extent that growth is limited by a lack of carbohydrates rather than a lack of minerals. In addition, even competition with free-growing herbs can be quite harmful. When evaluating the results of experiments with fertilizers, weather conditions and other environmental factors should be taken into account.

On this basis, it should be noted that good results are impossible in conditions when unfavorable environmental factors reduce the intensity of the main physiological processes to a level at which these processes do not change with the improvement of mineral nutrition. Typically, both strongly and weakly in need of nitrogen, species respond equally well to the application of nitrogen at its low content, but with an increase in the amount of nitrogen, the increase in growth decreases even in species whose need for it is high.

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