Biofertilizer explores the substances containing living microorganisms which, when applied to seeds or plant surfaces, promote growth by increasing the supply of primary nutrients.
Which of the following is/are used as biofertilizers?
Azolla
Blue-green algae
Alfalfa
Choose the correct answer by the given codes:
Correct Answer:
(B) 1 and 2
Biofertilizers are defined as preparations containing living cells or latent cells of efficient strains of microorganisms that help crop plants uptake of nutrients, by their interactions in the rhizosphere when applied through seed or soil. They accelerate certain microbial processes in the soil which aug ment the extent of availability of nutrients in a form easily assimilated by plants. They can be grouped in different ways based on their nature and function.
Nitrogen-fixing Biofertilizer: Azotobacter, Beijerinkia, Clostridium, Klebsiella, Anabaena, Nostoc, Rhizobium, Frankia, Anabaena azollae.
Phosphorus-solubilizing/mobilizing Biofertilizers: Bacillus megatherium var. phosphaticum, Aspergillus, Pezizella Ericae.
Biofertilizers for micronutrients: Bacillussps.
Plant Growth Promoting Rhizobacteria: Pseudomonas fluorescence.
Cyanobacteria (blue-green algae) and Azolla are used as biofertilizers. However, Alfalfa is a perennial flowering plant of the pea family.
Ques: 2
Which of the following is used as Biofertilizer?
Correct Answer:
(D)
All of these
Rhizobium, Blue-green algae (cyanobacteria) and Azolla, all are used as biofertilizer. They help in nitrogen-fixation.
Ques: 3
Which of the following is not a nitrogen-fixing organism?
Correct Answer:
(D)
Mycorrhiza
Nostoc, Anabaena and Azotobacter are nitrogen-fixing organisms while mycorrhiza is a symbiotic association between a fungus and a plant.
Ques: 4
Which of these is not correctly matched–
Correct Answer:
(D)
Azotobacter - Bio insecticide
Azotobacter is a Bacteria. Azotobacter naturally fixes atmospheric nitrogen in the rhizosphere (the zone surrounding the root of plants). So, option (d) is not correctly matched. Other three options are correctly matched.
Ques: 5
Which one of the following is not correctly matched?
Nitrogen fixing agent : Crop
Correct Answer:
(D)
Azolla - Maize
Azolla, anabaena, nostok, blue-green algae etc. promote nitrogen fixation in paddy harvesting. They work as organic fertilizers. Rhizobium leguminisarum in pea and azotobacter wheat promotes nitrogen fixation. Generally, azolla is not used for nitrogen fixation in maize. Thus, the correct answer is option (d).
Ques: 6
Which of the following is phosphatic biofertilizer?
Correct Answer:
(D)
Vascular Arbuscular Mycorrhiza
Rhizobium, Blue-green algae (Cyanobacteria) and Azolla help in nitrogen fixation, while Vascular Arbuscular Mycorrhiza (VAM) helps in uptake of phosphorus by the plant and hence, it is a phosphatic bio-fertilizers. VAM fungi benefit their host plant by improving the uptake of water, minerals and particularly the poorly mobile ion phosphorus in the soil. It also increases the plant's resistance against pathogens and improves plant tolerance to environmental stresses such as drought.
Ques: 7
What is the use of biochar in farming?
Biochar can be used as a part of the growing medium in vertical farming.
When biochar is a part of the growing medium, it promotes the growth of nitrogen-fixing microorganisms.
When biochar is a part of the growing medium, it enables the growing medium to retain water for longer time.
Which of the statements given above is / are correct?
Correct Answer:
(D)
1, 2 and 3
Biochar is a stable, carbon-rich form of charcoal that is applied to the soil. It is produced from heating organic materials like crop waste, grass, woodchips and manure in a high temperature, low oxygen process known as pyrolysis. Biochar can be used as a part of the growing medium in vertical farming. Adding biochar to soil increases its carbon content and can mitigate greenhouse gas emissions. Some biochars can improve soil fertility, water holding capacity and crop productivity. Research shows that biochars derived from grasses or crops appear to have the best balance of agricultural benefit and carbon stability. Some studies also show that increasing the application rate of biochar has a positive feedback on biological nitrogen fixation (BNF) and soil microbial biomass. The extremely porous nature of biochar is found to be effective at retaining both water and water-soluble nutrients, and it is very much suitable as a habitat for many beneficial soil microorganisms. From the above explanation, all of the given statements are correct.