TSPSC Group – I Mains,2024 Material useful for Paper - I : General Essay on ’Biofertilizers’ ; Paper V : Science and Technology Biotechnology :- ’Biofertilizers’

 

TSPSC Group – I Mains,2024

Material useful for Paper - I : General Essay

&

Paper V : Science and Technology

 ’Biofertilizers’

 

 

For  Examination guidance purpose only

For any clarification please refer to the prescribed text books

Time : 3 Hours                                                                                      Marks : 150 

 

Note : Answer all questions. Answer ONE question from each section.

Answer to each question should be limited to around 1000 words. All questions carry equal marks .

For GENERAL ESSAY PAPER :

Syllabus :

Section-I 1. Contemporary Social Issues and Social Problems. 2. Issues of Economic Growth and Justice.

Section-II 1. Dynamics of Indian Politics. 2. Historical and Cultural Heritage of India.

Section-III 1. Developments in Science and Technology. 2. Education and Human Resource Development

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 Paper V : Science and Technology :

Syllabus:

 II. Modern Trends in application of knowledge of Science:

1. Crop Science in India; Characteristics of Plants - Crop plants, Forest species, Medicinal Aromatic plants, Useful and Harmful plants and utility for mankind.

2. Concept of Biotechnology and application of genetic engineering and Stem Cell Research. Biotechnology in Agriculture (bio-fertilizers, bio - pesticides, bio- fuels, tissue culture, cloning) and Environment (Biotechnology in Environmental cleanup process)

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GENERAL ESSAY ON ‘BIO-FERTILIZERS’

 Unlike chemical fertilizers, biofertilizer technology is based on renewable resources of energy and does not contribute to environmental pollution.

 

As a low-cost technology it is most suitable for developing nations where labour is inexpensive and nutrient input for crop cultivation through chemical sources is meagre.

 

Various micro-organisms and associations with plants which are involved in biofertilizer production as well as their usage on the farm are here reviewed. Data on possible monetary benefits to the small farmer who uses these biofertilizers in India are presented and future strategies of research in this area are pointed out.

 

In addition to nitrogen, phosphorus also plays a vital role in plant growth and metabolism. Micro-organisms responsible for phosphate dissolution occur in intimate symbiotic association with plant roots and function as the liaison between the plant and the surrounding soil.

 

 Future biofertilizers will probably contain a blend of nitrogen-fixing and phosphate-mobilizing micro-organisms. Research aimed at developing these and at transferring nitrogen-fixing genes from bacteria into plants will result in a new biotechnology to minimize our dependence on chemical fertilizers

 

 

What is the Biofertilizer?

Ans:

Biofertilizer is a substance that basically contains different microorganisms which fixes nitrogen or mainly solubilizes phosphorus and potassium present in the upper layer of soil which is also called as rhizosphere, these microorganisms increase the basic nutrients in soil and stimulate the growth of plants. They increase the productivity of crop without harming the environment, for example a biofertilizer with phosphate solubilizing and nitrogen fixing capacity can fix upto 40 kilograms of nitrogen per acre.

  Biofertilizers can also be defined as microbial inoculants, which are made artificially to multiply the natural microorganism present in soil to improve the fertility and productivity of soil. Different microorganisms like bacteria, algae and fungus help as biofertilizer and fix or solubilize different components present in soil and atmosphere.

 Plants need different inorganic and organic elements to form macromolecules and micro molecules in the cells. But all the necessary elements are not present in the soil of a particular area, so we have to provide these essential elements like Nitrogen (N), Potassium (K), Phosphorus (P) in the form of chemicals to make the soil nutritious for plants and to grow the plants for the desired result. This chemical form of nutrition increases the yield of plants but they cause severe health hazards to plants

  1)Bacteria which are used as biofertilizers:

 

a)Azotobacter, (b)Azospirillum, (c)Rhizobium, etc.

 

 

2)Algae which are used as biofertilziers :

1) species of Cyanobacteria or Blue- green algae (BGA).

 

 Fungi which are used as biofertilizers:

1)Ectomycorrhizae and Endomycorrhizae in symbiotic relationship with higher plants for example Basidiomycota, Ascomycota and Glomeromycota and Arbuscular mycorrhizal (AM) fungi.

 

Different types of biofertilizers :

 1. symbiotic nitrogen fixing spp. (Rhizobim spp.);

2. asymbiotic free nitrogen fixing spp. (Azotobacter);

3. Azospirillum,

4. Algal biofertilizers (BGA or BGA with a symbiotic relationship with Azolla),

5. phosphate solubilising bacteria,  

6. Mycorrhizae

 Azotobacter as a biofertilizer is used since more than 100 years and in 1901 Martinus Beijerinck described Azotobacter . 

 Azotobacter belongs to Pseudomonadaceae or Azotobacteraceae family and its class is Gammaproteobacteria which generally can be found in normal soil across the globe.

 The most researched species of Azotobacter is A.vinelandii.

 When compared with other bacteria they are generally big in size, and has an oval shape (about 3µm wide and 10µm long). This bacterium  is gram negative in nature and produce pigments of different colour like reddish-violet, yellowish-green and brown-black.

 The Azotobacter which occurs naturally secrete large amount of sequester water and slime and during unfavorable environment they create cyst around them    to protect themselves, but this cyst is unable to fix the nitrogen in environment. 

 Azotobacter is found in the rhizosphere of the soil and it is present in neutral to alkaline pH soil. Azotobacter can fix atmospheric nitrogen in the free-living state without symbiotic association with any other plant discovered by Beijerinck in 1901

 Mycorrhiza as biofertilizer:

In nature, plant species are surrounded by both external and internal microorganisms. Some bacteria and mycorrhizal fungi play a key role in the growth and development of plants and can improve the quality of plant to a greater extent in stress condition and in favourable condition. Arbuscular Mycorrhizal Fungi (AMF) make mutual symbiotic relation with 80% of plant. What AMF do so it increase the area of roots, leading to increase in water and nutrient uptake. AMF inoculation has shown increase in plant production and growth and also it protect the plant from the environmental stress. AMF belongs to the phylum Glomeromycota and they are obligate symbiotic organism. The mycelium present in AMF which originated from roots of the plant helps to get more nutrition by increasing the surface area where plant roots cannot access. And, the hyphae of fungus are thinner in comparison to roots which can access the smaller area or pores. Macromolecules like carbohydrate and some of the minerals get inside the roots of plant where AMF are present, this AM fungus hypha create a branched structure and make a dense colony near the root cortex, that is called as “arbuscules” which is the main site of nutritional exchange. AMF also provides protection against flood, drought, high salinity, etc.. Some metals are very important like iron (Fe), zinc (Zn), and copper (Cu) but if their concentration is high it becomes toxic, but this AMF reduces the metal toxicity and help the plants to take the metal in sufficient amount for growth

 

Trichoderma as Biofertilizer:

Trichoderma is a genus of fungus which is used in agriculture which has many functions like it promote the growth of the plant also it provides protection against pathogens and it provide resistance against abiotic and biotic stress. It is a free living fungus which interacts with soil, root and plant surface. It is a symbiotic organism that is an endophyte and it establishes a direct relationship with plant by making a colony in the root system

 Blue-Green Algae or Cyanobacteria as Biofertilizer:

Blue-green algae also known as cyanobacteria are most copious photosynthetic prokaryotes. They are autotropic organism. It was the most primitive organism which evolved on the planet earth about 3.5 billion years ago. Some of the microfossils are found which are of precambrian era and was bigger from bacteria. It was the ancestor of cell organelle plastid and it was the only source of biogenic oxygen at the time when aerobic organisms started to originate. It can do two major things in plant that is Photosynthesis and Nitrogen fixation. Cyanobacteria occurs in wide range of soil and present in both below and on the soil. It presents in sub-aerial environment and also present sporadically in wet surface such as paddy field. In majority of the paddy or rice field cyanobacteria occurs naturally which fixes nitrogen without any cost. Cyanobacteria are capable of converting atmospheric Dinitrogen (N₂), Ammonia (NH₃), Nitrites (NO₂^–), Nitrates (NO₃^–) into absorbable nitrogen form. Amino acids like asparagine, arginine and glutamine are the important source of nitrogen in plants

 Azolla and Anabaena as Biofertilizer:

Anabaena azollae is a endophytic blue-green algae which lives in a symbiotic association with small water fern Azolla lam. to fix the nitrogen present in soil for itself and the host plant. Anabaena azollae fixes the nitrogen for Azolla lam. and Azolla lam. provide protection from the outer environment and fixes the carbon for the alga. Nitrogen is the most important element which is used in food production. The production of agriculture is dependent on the amount of nitrogen being given to the crops, in rice plants near about 21 kg N t^-1 is absorbed to produce the grain and it is constant

 Commercial Production of Biofertilizers in India: 

In 1920, N.V. Joshi started the use of Biofertilizers in India. Some of the marketed biofertilizers in India are-: 1). In nitrogen fixers, Azospirillum, Rhizobium, BGA, Azolla, Azotobacter, e.t.c. are being used. 2). In phosphate solubilizer, Pseudomonas, Aspergillus and Bacillus are being used. 3). In phosphate mobilizer VAM is used (VA-Mycorrhiza). 4). In potassium solubilizer, F.aurantia is used. 5). In plant growth promoting hormone biofertilizers Pseudomonas sp. is  used. In India the requirement of biofertilizers is near about 5.5 lakhs metric tons and it will increase by 50-60k in near future

 What are the benefits of using bio-fertilizers?

 Ans:

Benefits of using bio-fertilizers are described here. The side effects of using chemical fertilizers like NPK fertilizers in the agriculture sector which have caused several side effects on the environment such as reduced fertility of soil, accumulation of chemicals in the soil and NPK fertilzers are causing several harmful diseases in humans by contaminating the food and water. So, in this regard the use of biofertilizers comes into picture.

  1)    Bio-fertilizers are the naturally occurring microorganism like Bacteria, Algae, Fungi, Pteridophytes or ferns which provide the essential minerals naturally from the environment by fixing or solubilizing some essential elements. In this review article some microorganisms of different domains are being studied like bacteria, algae and fungi.

2)    Bacteria acts as a very good natural bio-fertilizers because it is mainly concerned with fixing the nitrogen from atmosphere into ammonia which plant can take and use. It also solubilizes the insoluble phosphate present in soil to soluble form.

3)    Fungi also act as a good source of bio-fertilizers they also fixes nitrogen and solubilizes the phosphorous but their main role is that they accumulate in the roots of plant and help to uptake the nutrient present in the soil which plant cannot take by itself because plant roots are not thin enough that it can go into small pores and take the nutrients.

4)    These nutrients are easily accessible by hyphae of the fungus. Fungi such as Mycorrhiza and Trichoderma are also used to resist the abiotic and biotic stress like droughts and flooding, etc. Algae such as cyanobacteria or BGA and Anabaena azollae, also acts as a natural bio-fertilizer by fixing the nitrogen present in air. The positive effect of using bio-fertilizers in agriculture is that, they are economically feasible and provide immense support to the natural environment because they just not only increase the agricultural production but also bio-remediate and bio-degrade the harmful wastes which are present in soil. The commercial production of some bio-fertilizers is possible and are going on in whole world. But some of the bio-fertilizers like Mycorrhiza can mainly grow in natural environment where roots of plant are available. There commercial production in an agar medium or liquid medium is difficult as compared to bacterial bio-fertilizers. That is why the development in the field of bio-fertilizers is going on steadily and development is going on the commercial production and to find out which is the microorganism that can be produced commercially to increase crop production and to make the environment clean by remediation