toxicity. A concentration, at which % of the dry weight of tissue is reduced, is considered as toxic. Figure . explains about Critical Concentration.
Concentration of Nutrient in Plant Tissue Critical Nutrient Concentration Transition Zone % Reduction In Plant Growth Growth as a % of Maximum Rate Deficient Zone Toxic Zone Adequate Zone Toxic Concentration Figure . : Critical Concentration . . Mineral Toxicity a.
Manganese toxicity Increased Concentration of Manganese will prevent the uptake of Fe and Mg, prevent translocation of Ca to the shoot apex and cause their deficiency. The symptoms of manganese toxicity are appearance of brown spots surrounded by chlorotic veins. b. Aluminium Toxicity Aluminium toxicity causes precipitation of nucleic acid, inhibition of ATPase, inhibition of cell division and binding of plasma membrane with Calmodulin.
For theories regarding, translocation of minerals please refer Chapter- . . Hydroponics and Aeroponics . Hydroponics or Soilless culture: Von Sachs developed a method of growing plants in nutrient solution.
The commonly used nutrient solutions are Knop solution ( ) and Arnon and Hoagland Solution ( ). Later the term Hydroponics was coined by Goerick ( ) and he also introduced commercial techniques for hydroponics. In hydroponics roots are immersed in the solution containing nutrients and air is supplied with help of tube (Figure . ).
Aeroponics: This technique was developed by Soifer Hillel and David Durger . It is a system where roots are suspended in air and nutrients are sprayed over the roots by a motor driven rotor (Figure . ). Suspended root Mist chamber Nutrient Solution Spray rotor Figure .
: Aeroponics . Nitrogen Fixation Inspiring act of nature is self-regulation. As all living organisms act as tools for biogeochemical cycles, nitrogen cycle is highly regulated. Life on earth depends on nitrogen cycle.
Nitrogen occurs in atmosphere in the form of N2 (N ≡ N), two nitrogen atoms joined together by strong triple covalent bonds. The process of converting atmospheric nitrogen (N ) into ammonia is termed as nitrogen fixation. Nitrogen fixation Water circulation pump Air bubble Air pipe Buoyant pads to support the plants Nutrient solution Air pump Figure . : Hydroponics