A technique to grow plant without soil, Hydroponics

 

Soil is a reservoir of nutrients for plants . Plants absorb all essential nutrients from the soils through the roots. The essentiality of nutrients for the growth of plants is essential. Moreover soil is essential for the growth. All living organisms require both organic and inorganic nutrients for their growth and development.

Most of the minerals present in soil can enter plants through roots. Some plant species accumulate selenium like Barley, Wheat etc and  some plants like Alfalfa  absorb gold,   while some plants  can be seen  near nuclear test sites to  take up  the radioactive strontium.

Need of Nutrients in Plants 

The nutrients are essential  for the normal growth and reproduction of plants.

The requirements of the nutrients are  specific for growth and metabolism of plants.  The need for nutrients are not replaced  by another substitution because they are directly involved in the metabolism of the plant.

Two Broad categories of Nutrients in Plants 

Essential Nutrients are further divided into two broad categories based on their quantitative requirements

The nutrients that  are generally present in plant tissues in large amounts called Macronutrients.

The macronutrients include carbon, hydrogen, oxygen, nitrogen, phosphorus, sulphur, potassium, calcium and magnesium.

The nutrients  that are present in traces and  are needed in very small amounts by plants called micronutrients. Micronutrients include iron, manganese, copper, molybdenum, zinc, boron, chlorine and nickel.

Besides the  Macro and micronutrients, there are some other  elements such as sodium, silicon, cobalt and selenium that are also needed by the plants as Essential nutrients or Elements.

Essential elements can be divided into following  broad categories  on the basis of their functions.

Essential elements  that are needed  to be components of biomolecules.  So they are termed as  structural elements Example- carbon, hydrogen, oxygen and nitrogen.

Some essential elements are required  for formation of energy elements  in plants. Example- Magnesium in chlorophyll.

Those essential elements that activate or inhibit  the activity of enzymes are called activator or inhibitor .For example- Mg2+ is an activator for both ribulose bisphosphate carboxylase oxygenase and phosphoenol pyruvate carboxylase, both of which are critical enzymes in photosynthetic carbon fixation.

Some essential elements can alter the osmotic potential of a cell. For example- potassium plays an important role in the opening and closing of stomata.

Hydroponics 

It is a technique in which plants are grown in aqueous solution without the soil.This solution includes all the essential nutrients that are required for growth and metabolism for the plants.

There are several examples of hydroponics including the hanging gardens of Babylon and the floating gardens of China and Aztec Mexico. 

In 1600, Von Helmont  demonstrated that a  shoot of plant was grown  in the soil for five years while providing Water at regular intervals. He observed that when a plant attained full growth, its weight was more than the consumption of the soil. It indicated that plants consume  more water than the soil. 

In the 1960, German scientist Julius von Sachs experimented with growing plants in water-nutrient solutions. He demonstrated that plants could be grown to maturity in a defined nutrient solution in complete absence of soil.

The technique of growing plants in a nutrient solution without the soil  is known as hydroponics.

Hydroponics has been successfully employed as a technique for the commercial production of vegetables such as tomato, seedless cucumber and lettuce.