07 Plant Growth and Mineral Nutrition - part 03 - Conditions for Growth

07 Plant Growth and Mineral Nutrition - part 03 - Conditions for Growth


Conditions for Growth : 
  • The different environmental and physiological conditions necessary for the growth include - 
  1. Water
  2. supply of nutrient
  3. temperature
  4. oxygen
  5. Carbon/ Nitrogen ratio
  6. gravitational force
  7. light and 
  8. growth hormones. 
The chief conditions are explained below :
1. Water
  • Water is the essential component of protoplasm and maintains turgidity of the cell. 
  • It acts as aqueous medium for biochemical reactions. 
2. supply of nutrient

  • Microelements and Macroelements are nutrients required for the proper growth of the plant. 
3. Temperature :
  • Optimum Temperature ranges between 25-350C. 
4. Oxygen  :

  • Oxygen is essential for respiration and the release of energy. 
5. Light :
  • Light is very much essential for germination of seed and photosynthesis. 
6. Gravitational force :
  • Gravitational force decides the direction of growth of the shoot and root.
Growth in plants can be measured in terms of....
  1. Increase in the number of cells produced - e.g. single maize root apical mesistem can give rise to more than 17,500 new cells/Hour. 
  2. Increase in surface area of the leaf - e.g. growth of dorsiventral leaf. 
  3. Increase in length - e.g. growth of pollen tube. 
  4. Increase in volume of a fruit - e.g. In watermelon flower, ovary after fertilization increases in its size/ volume by upto 3,50,000 times. 
  5. Increase in girth of shoot. 
  6. Increase in dry weight of organ.
Various methods for the measurement of linear growth of stem and radicle are as follows:
1. Direct method : 
  • It can easily be measured with the help of ordinary measuring scale. 
  • It is a simple method. 
2. Horizontal microscope : 
  • It is used to measure growth in fields. 
3. Auxanometer : 
  • This equipment is used for precise measurement of linear growth of shoot. 
  • There are two types of an auxanometers viz- 
  1. Arc auxanometer
  2. Pfeffer's auxanometer 
4. Crescograph : 
  • It records primary growth very accurately. 
  • It magnifies growth upto 10,000 times giving information of growth per second. 
  • It is developed by sir J. C. Bose.

Comments

Post a Comment

Popular posts from this blog

6. Biomolecules - part 01 - Carbohydrates

Image
  6. Biomolecules - part 01 - Carbohydrates Introduction : Our planet is having a wide diversity of living organisms that are classified as - unicellular  (consisting of a single cell; including bacteria and yeast) or  multicellular  having many cells (e.g. plants and animals).  living organisms have cell as the basic structural and functional unit.  The cells have protoplasm containing numerous chemical molecules, the biomolecules. Biochemistry  : Biochemistry is  biological chemistry  that provides us the idea of the chemistry of living organisms and molecular basis for changes taking place in plants, animals and microbial cells.  It develops the foundation or understanding  all biological processes  and communication within and between cells as well as chemical basis of inheritance and diseases in animals and plants. Chemical analysis of all living organisms indicates presence of the most common elements like  carbon, h...
Read more

6. Biomolecules - part 02 - Lipids

Image
  6. Biomolecules - part 02 - Lipids B. Lipids : These are group of substances with greasy consistency with  long hydrocarbon chain containing carbon, hydrogen and oxygen. In lipids, hydrogen to oxygen ratio is  greater than 2:1  (in carbohydrates it is always 2:1). Lipid is a broader term used for fatty acids and their derivatives.  They are soluble in organic solvents (non-polar solvents).  Fatty acids are organic acids which are composed of hydrocarbon chain  ending in carboxyl group (-COOH).  They can be  saturated fatty acids  with no double bonds between the carbon atoms of the hydrocarbon chain.  Palmitic and stearic acids  found in all animal and plant fats are examples of saturated fatty acids. Unsaturated Fatty Acids  are with one or more double bonds between the carbon atoms of the hydrocarbon chain.  Oleic acid  found in nearly all fats and  linoleic acid  found in many seed oils are example...
Read more

6. Biomolecules - part 05 - Enzymes

Image
  6. Biomolecules - part 05 - Enzymes Enzymes : Thousands of different chemical reactions take place automatically at a given time in a tiny living cell. The reactions take place at the body temperature.  If these enzymes were not present in the cell, either the reactions would not occur or if they occur they would occur at a  very very slow rate . Know the scientists : German chemist  Edward Buchner  discovered enzymes by accident.  Buchner discovered that living cells were not necessary but that  yeast  extract could bring about fermentation.  He then coined the term Enzyme (Gk. En = in, zyma = yeast i.e. in yeast). This term is now commonly used for all biocatalysts. Each enzyme catalyzes a small number of reactions, specifically perhaps only one. Substrate :  The substance upon which an enzyme acts is termed as the substrate.  Endo-enzymes :  The enzymes which act within the cell in which they are synthesizedare known as en...
Read more