An Introduction to Hydroponics MCQ - Practice Questions with Answers

• Absorption, utilization and assimilation of inorganic compounds or minerals by plants for synthesis of essential material for their growth, development, structure and physiology is called Mineral nutrition. 
• Mineral nutrients are the inorganic compounds obtained from the soil and are used as a raw material by the plants.

Methods to study the mineral requirements of plants: Hydroponics

• In 1860, Julius von Sachs, a prominent German botanist, demonstrated, for the first time, that plants could be grown to maturity in a defined nutrient solution in the complete absence of soil. 
• This technique of growing plants in a nutrient solution is known as hydroponics. 
• The essence of all the improvised hydroponic methods involves the culture of plants in a soil-free, defined mineral solution.
• These methods require purified water and mineral nutrient salts.
• After a series of experiments in which the roots of the plants were immersed in nutrient solutions and wherein an element was added /substituted/ removed or given in varied concentration, a mineral solution suitable for the plant growth was obtained.
• By this method, essential elements were identified and their deficiency symptoms discovered. 
• Hydroponics has been successfully employed as a technique for the commercial production of vegetables such as tomato, seedless cucumber and lettuce.
• It must be emphasised that the nutrient solutions must be adequately aerated to obtain optimum growth.

Hydroponics helps in knowing:

• The essentiality of the mineral element.
• The deficiency symptoms developed due to non-availability of a particular nutrient.
• Toxicity to plant when an element is present in excess.
• Possible interaction among different elements present in plant.
• The role of an essential element in the metabolism of the plant.

Types of Hydroponics:

1. Tank System: the roots are immersed in the nutrient solution and the air is bubbled through the solution.

2. Film technique: plants are grown in a trough or tube having a thin film of recirculated nutrient solution.

Aeroponics:

• Aeroponics is the practice of growing plants in an air or mist environment without the use of soil.
• It involves fogging the roots of the plants with a nutrient solution.
• The plants are usually housed in troughs, tubes or foam.
• Roots are constantly exposed and sprayed with microbursts of atomized water.

Mineral Nutrient Solutions:

1. Sach’s Solution: It contributes a total of nine mineral nutrients as K, N, P, Ca, S, Na, Cl, Fe, Mg.

2. Hoagland Solution: It contains all of the known mineral nutrients needed for rapid plant growth.