Mineral Deficiencies (Definition And Examples)

The Growing plant requires many nutrients, in the form of minerals obtained from the soil as well as water, oxygen and carbon dioxide. Carbon, hydrogen and oxygen are combined together to form carbohydrates, the organic foods of plants. The minerals, which are termed inorganic compounds, are formed in the soil as a result of decomposition and weathering of rock material and many of these are soluble. The soil water therefore is a dilute solution of minerals, often in the form of chlorides, sulphates, phosphates and nitrates. Plants require these compounds for normal growth and development, the rate at which they can be absorbed depends mainly on the growth rate of the plant. Plants which grow to a large size and produce many leaves use more nutrients than smaller-growing ones, but some types of plant use more of some kinds of elements, as these plant nutrients are commonly termed, than others.

The essential elements used by plants can be considered in two main groups, the major or macro-elements and the minor, micro-, or trace elements which occur in the soil in very limited amounts and are also absorbed by plants in very minute quantities.

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POLLINATION, INSECT POLLINATION MECHANISMS AND IT IMPORTANT

A) Major elements Carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), and sulphur (S). The symbols in brackets are those commonly used as abbreviations of these elements.

B) Minor elements Iron (Fe), copper (Cu), molybdenum (Mo), boron (B), manganese (Mn), chlorine (Cl) and silicon (Si). All of these elements, when absorbed by the plant, have specialised functions; when they are not available the plant reacts to these deficiencies and very often shows a change in leaf colour, reduction in the development of flowers and seeds and various other external characteristics. By careful observation, many of these deficiencies can be detected and a corrective  treatment applied. The experienced farmer should be able to prevent the occurrence of some of the major deficiciencies by following a good standard of management.

The following are the major deficiencies which can occur in agricultural crops and treatments  which can normally correct the  condition if the crop is not too mature.

Nitrogen This is probably one of the most important of the plant nutrients, occurring in the soil mainly as ammonium compounds and nitrates. It is involved in the production of plant proteins and therefore has a most important function in the development of leaves, fruits and tubers. It regulates, to some extent, the efficient use of phosphorus and potassium by the plant. A lack of nitrogen produces a stunted plant, with a reduced root system and often yellow lower leaves. The application of nitrogenous inorganic fertilisers and organic  manure will correct this deficiency.

The way in which nitrogen is maintained in the soil by the activity of bacteria which is a diagrammatic outline of the nitrogen cycle. An excess of nitrogen leads to delayed maturity and excessive lengthening and weakening of the  stems of cereals, causing lodging or bending.

Phosphorus This element is concerned in the development of plant vigour and assists the plant in achieving early maturity as well as the development of a strong root system. It can, to some extent, reduce the effects of nitrogen deficiency. Leaves of deficient plants become grey, purple or bronze in colour.

Potassium This element is generally regarded as influencing the quality of fruits and seeds, it also improves the resistance of plants to disease and insect attack. It is required by plant leaves for the formation of chlorophyll and therefore a deficiency can affect the production of carbohydrates such as sugars by the leaf.

Potassium deficiency is observed as a browning and scorching of the edges of leaves and also a yellowing of the areas between the leaf veins. 

Calcium is used in relatively small quantities by plants, although it is an essential element. A lack of calcium in the soil generally leads to an inefficient use of water by the plant which may lead to breakdown of plant tissues normally referred to as 'physiological disorders'. The young leaves of calcium deficient plants die back at the tips and margins, the  terminal bud finally dies in extreme cases of deficiency.

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CELLS & DIFFERENT BETWEEN PLANT AND ANIMAL CELLS

Magnesium This is essential for the formation of chlorophyll in leaves and the production of some plant oils. Plants which are deficient in this element have brown patches on their leaves, some plants may also develop yellow, red or purple leaf colours, the tips of leaves may turn upward and leaves may fall carly.

Sodium This element can partly replace potassium in some plants and some plants, particularly those which grow in arid regions, can tolerate high levels of sodium in the soil. Deficiencies of sodium are difficult to of detect since no obvious leaf or stem disorders result from this condition Sulphur Although present in limited quantities in the soil, mainly in the form of sulphides, most crops appear to obtain adequate amounts of sulphur which is mainly involved in the production of proteins and some oils. Light green leaves are a symptom of this deficiency which affects both the leaf blade and the leaf veins.

Iron Although associated with the production of chlorophyll, iron is not part of the chlorophyll molecule. Yellowing of the leaves indicates a deficiency of this element which can be induced in soils by excess applications of phosphate. This deficiency is most likely to occur on soils high in  phosphate and on alkaline soils. High levels of phosphate can reduce the

availability of iron to the plant, even in soil with an adequate iron content.

Copper This has a function in  promoting enzyme reactions in plants and is essential for photosynthesis.

Soils which are rich in organic material can sometimes be deficient in copper. An excess of copper can cause a deficiency of iron. Young leaves of copper-deficient plants wither at the tips and remain permanently wilted, but do not become yellow.

Zinc This is similar in reaction to copper. Leaves of deficient plants sometimes become thickened and develop spotted areas. A deficiency of zinc can be induced by liming, but a high organic content and high phosphorus levels can also induce a deficiency.

Molybdenum This is involved in the formation of nodules in legumes and a high soil pH may cause plants to absorb excessive amounts of molybdenum.

Deficiency can cause the internal blackening of tissues in some leafy crops belonging to the Brassica group.

Boron Very minute amounts of boron are required by plants for healthy growth, but deficiencies cause the breakdown of leaf tissues, often causing twisting. Boron is considered to be involved in the utilisation of other essential elements. Alkaline soils are most likely to be deficient in boron.

Manganese A high content of organic material and sometimes nitrogen may contribute to a deficiency of manganese which can be induced by adding lime to the soil. Neutral or alkaline soils are more likely to be deficient in manganese than acid soils. A deficiency Causes spotting of the leaves of some plants and a general yellowing. Manganese is associated with

enzyme systems which are involved in the formation of proteins.

Chlorine and silicon These elements are normally found to be present in plants but their exact functions are not clear. Silicon appears to either increase the

amount of phosphorus available in the soil or it may have some effect on the intake of phosphorus by plants.