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.