Essential elements in Plants

Scientists related to plants have demonstrated that there are sixteen essential elements that are needed in plants for their normal growth and metabolism.

These elements are categorized into the following categories- 

Nutrients that are required by the plants at larger amounts are called  Macronutrients or termed as Primary nutrients. These primary nutrients  are carbon, hydrogen, nitrogen, oxygen, phosphorus, and potassium.

Nutrients that are required by the plants at medium  amounts either excess  or least are called secondary  nutrients. The secondary nutrients are calcium, magnesium, and sulphur.

And the third one is Micronutrient. Word trace nutrients are also used for micronutrients . Micronutrients are boron, chlorine, copper, iron, manganese, molybdenum, and zinc.

Gold selenium.cobalt, nickel, silicon, sodium, and vanadium are other nutrients also absorbed  by the plants. 

Defeciency symptoms of essential elements 

The concentration of the essential element must be normal in plant if concentration remain present  below the normal range than plant growth is retarded.This concentration is called  as critical concentration.

The element is said to be deficient when present below the critical concentration.

In the absence of any essential element, plants develop various  morphological changes. These changes  are indicators of  deficiencies of essential elements and are called deficiency symptoms.

The deficiency symptoms may different from element to element and they disappear when the deficient elements get fulfilled  by the plant.

The deficiency symptoms appear first in the young tissues whenever the elements are relatively immobile and are not transported out of the mature organs. For example, elements like sulphur and calcium are a part of the structural component of the cell and hence are not easily released. 

The common  deficiency symptoms in plants include chlorosis, necrosis, stunted plant growth, premature fall of leaves and buds, and inhibition of cell division.

Chlorosis is the loss of chlorophyll leading to yellowing in leaves, caused by the deficiency of elements Nitrogen, Potassium Magnesium Iron zinc Molybdenum.

Necrosis is the death of tissue, particularly leaf tissue, due to the deficiency of Calcium Magnesium copper. Low level of Nitrogen sulphur Molybdenum affect  the process of cell division and also delay in  flowering.

Deficiency of  Essential nutrient affects specific functions of plant growth and development .Plant growth is limited.

Essential nutrients must be broken down into its basic form for the intake of plants. The nutrient must be in the form of either a positively charged ion or a negatively charged ion. If elements are converted into its basic forms then plants cannot use them.Plants cannot use elements in their original form and  if it is present in high concentrations in the soil. 

Plants take in almost all of the essential nutrients through their roots. The exception is carbon, which is taken in through leaf pores, or stomata.

Microorganisms like Bacteria Fungi  cyanobacteria or Biofertilizers break down organic compounds into inorganic compounds.This process is called mineralization.It is one of the important steps of decomposition. For example Fungi makes available for some plants to take up phosphorus by increasing the size of the roots. 

Due to the  lack of an essential nutrient, Plant cannot complete its life cycle.The seed may not germinate. The development of  roots, stems, leaves,  flowers ,fruit may be affected. Plant is not able to produce seeds. 

Toxicity of Elements

If there is  too much nutrient  present in plants, it can harm and even kill plants. For example, having too much nitrogen can cause a plant to grow more leaves but less or no fruit. Too much manganese can make the leaves turn yellow and eventually die. And excess boron can kill a plant.

The increase of elements in more amounts  causes toxicity.

Any mineral ion concentration in tissues that reduces the dry weight of tissues by about ten per cent is considered toxic.

Excess of an element may inhibit the uptake of another element. For example- the prominent symptom of manganese toxicity is the appearance of brown spots surrounded by chlorotic veins.

Manganese competes with iron and magnesium for uptake and with magnesium for binding with enzymes.

Manganese also inhibits calcium translocation in shoot apex; therefore, excess of manganese may induce deficiencies of iron, magnesium and calcium.