Criteria for Essentiality

Plant Nutrition - Plants that uses different mineral and water for their nutrition is called plant nutrition. Weathering of rock mixing of dead bodies of plants and animals with the soil make the soil fertile and there is addition of different elements within the soil from the body of the organisms. This this type of elements and organisms are the major source of different macro and micro elements which are associated with the development and growth of the plant. This elements remain in the soil as a form of salt or ions which then either dissolve in water or mix with water and actively transported by the xylem tissue to the leaves of green plants. Uptake of nutrients by the root of plant is dependent upon the pH of the soil as extreme alkalinity may effect the uptake or extreme acidity may also affect the uptake.

In 1939 Arnon and Stout express the term essentiality of the nutrients by the plants, according to them the elements those are categorised in the Essential elements that element must fulfill this criterias below.

Elements must have important role in the cycle of plant metabolism-an element is only said to be essential when its main function directly associated with the several activities in plants life so that deficiency of it main express a proper appropriate symptom.

Absence of that particular element cannot be substituted with the other elements - if the specific elements have a specific function in the development and metabolism of the green plants . So absence of any one of the element may affect the plants life.

That element which is essential for plant nutrition must have specific and direct role in metabolism- because that elements will be essential only for their function in the direct physiological activities or metabolism in plants body.

These are the major function and criteria for the essential element. But Essential elements are different from beneficial element because beneficial elements include those who  are having important role in the neutralization of toxicity of other elements or can be substituted for the function of other elements have some beneficial role on the development of the plants life. Application of beneficial elements means plants are not growing and developing according to their genetic capability but they are controlled by the application of different beneficial materials for planning development.

Minerals that are required for the growth of the plants are following-

1. Carbon hydrogen oxygen are supplied by the air to the plants that enter the plant by the pores of the stomata.

2. 6 macronutrients like nitrogen potassium Phosphorus Sulphur calcium magnesium they get from the soil as a comma salt feet enter the plant body by the active transport or osmosis by dissolved in the water through the unicellular root hair.

3. Rest of the elements are required in very small amount and are known as micronutrients. They are required very small in amount but without them their presence, there are appearance of some symptoms in the plants. The micronutrients are chlorine copper iron manganese magnesium zinc sodium molybdenum Nickel Silicon Cobalt.

Eleventh Grade

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