Important points
- Hydroponics is the technique of growing plants in a defined nutrient solution in the complete absence of soil.
- Hydroponics is also called soil-less culture.
- First demonstrated by the German botanist Julius von Sachs in the 1860s.
Setup
- A defined nutrient solution containing all the essential elements in the concentrations required by the plant.
- Sterile equipment to prevent contamination.
- An opening for adding fresh nutrient medium.
- An opening for aeration.
- A dark covering to prevent algal growth.
Aeration is needed because the roots need oxygen for respiration. The nutrient solution is made with purified water and mineral salts, so that only the elements added on purpose are present.
Applications
- Helped to identify the mineral nutrients essential for plants, by performing a series of experiments in which an element was added, substituted, removed or given in varied concentrations in the mineral solution.
- Hydroponics also helped to identify the deficiency symptoms associated with essential elements.
- Hydroponics is used as a technique for the commercial production of plants like tomato, seedless cucumber and lettuce.
- Can be used to grow plants in areas having low soil fertility, abnormal soil pH or soil containing pathogens.
The elements found this way are judged by three criteria for essentiality: the element must be absolutely necessary for normal growth and reproduction, its requirement must be specific (no other element can replace it), and it must be directly involved in the plant’s metabolism.