Question

Which of the following is not a biofertilizer
1. Rhizobium
2. Mycorrhiza
3. Azolla
4. Bacillus thuringiensis

Answer 1

Correct Answer - Option 4 : Bacillus thuringiensis

Concept:

• 'Biofertilizer' is a substance which contains living microorganism which, when applied to seed, plant surfaces, or soil, colonizes the rhizosphere or the interior of the plant and promotes growth by increasing the supply or availability of primary nutrients to the host plant. Biofertilizers are not fertilizers.
• Fertilizers directly increase soil fertility by adding nutrients. Biofertilizers add nutrients through the natural processes of fixing atmospheric nitrogen, solubilizing Phosphorus, and stimulating plant growth through the synthesis of growth-promoting substances.

Explanation:

• The major sources of Biofertilizers include Algae, Fungi, Cyano-bacteria & pteridophyte
• Atmospheric nitrogen cannot be absorbed directly by the plants so it is first converted into stable compound ammonia (NH3) in the roots, with the help of bacteria present in the biofertilizers.
• N2 → N2H2 → N2H4 → 2NH3

​ (nitrogen) (dimide) (hydrazine) (ammonia)

• Some of the biofertilizers include Rhizobium, Mycorhizza, Azolla

 

• In leguminous plants, Rhizobium bacteria helps in fixing the atmospheric nitrogen
• Azolla pinnata serves as a great biofertilizer for paddy crops (rice). It increases the nutrient uptake and grain yield of rice.
• Mycorrhiza is a symbiotic association of a fungus with a root system.

• Bacillus thuringiensis is used as a biopesticide. It is a vector used for preparing genetically modified organisms that are specific pest resistant. Crop prepared using Bacillus thuringiensis is BT Cotton for control of pest Bollworm.