Plant Physiology - Musienko M. M. 2001

Root Mineral Nutrition of Plants
Typical symptoms of mineral nutrient deficiency in various

Plants

Quite often, when certain mineral nutrients are lacking, distinct deficiency symptoms appear in various PARTS OF THE plant Organism. Sometimes these symptoms depend not only on the presence of a specific element, but also on its mobility within the plant.

Elements such as nitrogen, phosphorus, sulfur, potassium, and magnesium are highly mobile and capable of reutilization by the plant. When these elements are deficient, they are readily translocated from older Organs to younger ones, where they are re-assimilated. Consequently, deficiency symptoms for these elements appear first on older leaves.

Conversely, elements such as calcium, iron, and boron have poor mobility within the plant and are incapable of being reused. They accumulate in Aging Tissues, while deficiency symptoms readily manifest on younger, actively growing organs.

It should be noted that for the normal functioning of a plant organism, a specific ratio of various cations must be maintained. Solutions characterized by a specific cation ratio that is favorable for the GROWTH AND DEVELOPMENT of organisms are termed balanced. In some cases, the presence of one ion inhibits the uptake of another, a phenomenon known as ion antagonism. For example, an excess of manganese ions impedes iron absorption, which in turn suppresses chlorophyll Biosynthesis. Boron accelerates cation uptake while reducing anion absorption. One of the reasons for the antagonistic action of ions may be their effect on the colloidal and Chemical properties of the Cytoplasm, particularly on protein Hydration. Indeed, divalent cations (Ca²⁺, Mg²⁺) dehydrate colloids more strongly than monovalent ones (Na⁺, K⁺). It is also hypothesized that ion antagonism is largely due to their competition for the active sites of Enzymes.

At the same time, in certain instances, The Effect of one ion enhances the action of another. This phenomenon is known as synergism. For example, the positive effect of molybdenum is enhanced in the presence of phosphorus. Thus, the normal growth and Development of Plants requires a specific ratio of monovalent to divalent cation salts.

Nitrogen

The most pronounced symptom of nitrogen deficiency is leaf yellowing, which indicates impaired chlorophyll biosynthesis. In some plants, anthocyanins are intensively synthesized, resulting in a reddish tint on the petioles and leaf Veins. A severe nitrogen deficiency even induces premature leaf drop. All affected plants exhibit weak or stunted growth.

Phosphorus

Phosphorus starvation leads to the appearance of necrotic spots on leaves and unripe fruits. The foliage acquires a bluish-green hue, and occasionally an accumulation of anthocyanins is observed. Stems are characterized by poorly developed vascular systems. Phosphorus deficiency disrupts normal reproductive processes, notably delaying flowering.

Potassium

A shortage of this element disrupts the plant's Water balance; tip dieback is frequently observed, and the outflow of assimilates is reduced. Chlorotic yellow spots appear on the leaves. Necrotic areas form, and the margins and tips of the leaves often curl.

Magnesium

The primary symptom of magnesium deficiency is intense yellowing of the leaf parenchyma, as magnesium is an integral component of chlorophyll. Characteristic features include weak growth and interveinal chlorosis of older leaves.

Sulfur

Symptoms of sulfur deficiency are similar to those observed under nitrogen shortage. These primarily include leaf yellowing and The Development of anthocyanin pigmentation. However, unlike nitrogen deficiency, these symptoms appear first on young leaves.

Calcium

A deficiency of this element causes damage and necrosis in the meristematic zones of stems, roots, and leaves, thereby disrupting normal Plant Growth and stunting development. Affected plants typically feature twisted roots, tightly curled leaves, and significantly rigid Cell walls.

Iron

A typical sign of iron deficiency is interveinal chlorosis progressing to complete bleaching of young leaves, while the veins themselves remain green.

Manganese

Under manganese deficiency, yellow and necrotic spots appear on the leaves. METABOLISM/14.html">Chloroplasts are particularly sensitive to its shortage, exhibiting the degradation of their internal components. Plant growth is inhibited.

Copper

Starvation leads to tip dieback and chlorosis of young leaves. Leaf tips turn white and die. In fruit trees, both leaves and fruits become covered with brown spots.

Zinc

The deficiency of this element primarily affects young upper leaves and organs. The size of the leaf blade decreases, and its shape changes. Growth inhibition leads to so-called rosette growth, where the phyllotaxy acquires a rosette shape, internodes become shortened, and chlorosis appears on the leaves.

Boron

Young, growing organs are particularly sensitive to its deficiency. The most typical symptom of deficiency is the dieback of growing points, cessation of SHOOT and ROOT growth; leaf blades thicken, curl, and become brittle; flowers fail to form, and developmental disorders of The Vascular System are observed. Normal fruiting is disrupted, and fruit hardening occurs. It can cause A number of diseases, for example, Heart rot in sugar beets.

Molybdenum

A deficiency of this element disrupts normal growth and causes shoot deformation. The edges of the leaves turn gray, then brown, and lose turgor. Subsequently, the leaf tissues die off, leaving only the veins.