Biofertilizers pk mani
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Bio-fertilizers
Dr. P. K. ManiBidhan Chandra Krishi Viswavidyalaya
E-mail: [email protected] Website: www.bckv.edu.in
Bio-fertilizers or microbial inoculants are the carrier-based preparations containing sufficient number of microorganisms in a viable state inoculated to soil or seed to augment the nutrient availability to plant by enhancing the growth and proliferation of microorganisms.
A biofertilzer is an organic product containing a specific microorganism (microbial inoculant) in concentrated form (107 to 109 g-1), which is derived either from the nodules of plant roots or from the soil of root zone (Rhizosphere).
Biofertilizers may be referred to as inoculants after the name of microorganisms they contain, viz. Rhizobium inoculant or Azospirillum inoculant
Energetics
Industrial fixation NNHaber-Bosch (100-200 atm, 400-500°C, 8,000 kcal kg-1 N)
3CH4 + 6H2O --> 3CO2 + 12H2
4N2+12H2 --> 8NH3
Biological Nitrogen Fixation Nitrogenase (4,000 kcal kg-1 N)
Carl Bosch(1874-1940)
Fritz Haber(1868-1934)
Haber and Bosch: Most influential persons of the 20th Century ( Nature, July 29,1999)
In 1828, the German chemist Friedrich Wöhler obtained urea artificially by treating silver cyanate with ammonium chloride.[5][6][7]
AgNCO + NH4Cl → (NH2)2CO + AgCl
This was the first time an organic compound was artificially synthesized from inorganic starting materials, without the involvement of living organisms. The results of this experiment implicitly discredited vitalism: the theory that the chemicals of living organisms are fundamentally different from inanimate matter.
The relationship between activation energy ( ) and enthalpy of formation (ΔH) with and without a catalyst, plotted against the reaction coordinate. The highest energy position (peak position) represents the transition state. With the catalyst, the energy required to enter transition state decreases, thereby decreasing the energy required to initiate the reaction.
In chemistry, activation energy is a term introduced in 1889 by the Swedish scientist Svante Arrhenius that is defined as the minimum energy that must be input to a chemical system, containing potential reactants, in order for a chemical reaction to occur. Activation energy may also be defined as the minimum energy required to start a chemical reaction. The activation energy of a reaction is usually denoted by Ea and given in units of kilojoules per mole.Activation energy can be thought of as the height of the potential barrier (sometimes called the energy barrier) separating two minima of potential energy (of the reactants and products of a reaction). For a chemical reaction to proceed at a reasonable rate, there should exist an appreciable number of molecules with energy equal to or greater than the activation energy.
Chemical fertilizers Vs Biofertilizers
FEATURES CHEMICAL FERTILIZER BIOFERTILIZER
Raw material Non-renewable Renewable
Energy Fossil Fuel Solar
Reductant H2 Organic
Catalyst Al, Fe, Mo oxides Nitrogenase enzy
Temp. & Pr. 750oF, 200-600atm Ambient T, P
Energy reqt. 680 kJ.mol-1.NH4+ 355 kJ.mol-1.NH4
+
Efficiency 40-45% 90%
Pollution effect Exists due to indiscriminate use Pollution free
Cost High cost input @ Rs. 6/kgN Rs. 14/kg P2O2
Low cost input @Rs. 0.20/kg
Soil Health Deteriorates Improves
Classification of Bio fertilizers Nitrogen fixer Phosphate fixers Organic
matter decomposer
i) Symbiotic Rhizobium (legume)
Frankia (non-legume)
Phosphate solubilizers: Bacillus Pseudomonas Aspergillus Penicillium
Phosphate mobilizers:
VAMGlomus, Gigaspora
a)Cellulolytic:
Trichoderma
b)Lignolytic:
Agaricus, Polyporus
ii)Associative
BGA: Anabaena (Azolla)
AzospirillumBeijerinckia,
iii)Free living(Non-symbiotic)
Azotobacter , Clostridium,Acetobacter
Frankia-filamentous gram positive actinomycetes (vesicles for N fixation site). Actinorhizal plants are Alnus, Myrica, Casuarina
Symbiotic Nitrogen Fixation
Microorganisms Host plants Location Isolated
Large group Genera Plant group TissueInside or outside plant cell
Bacteria (-Proteobacteria)
Rhizobium, Bradyrhizobium Azorhizobium
Legumes and Parasponia
Nodule (induced)
Inside Yes
Actinomycetes FrankiaBetulaceae and8 family(trees)
Nodule (induced)
Inside Yes
Cyanobacteria(BGA)
Nostoc Bryophytes (Antheros etc.)
Leaf cavity
Outside Yes
Nostoc (Anabaena)
Pteridophyte(Azolla)
Leaf cavity
Outside No
Nostoc Cycadophyta (Cycas,Macrozamia etc.)
Collaroid root
Outside Yes
Nostoc Angiosperm(Gunnera)
Gland tissue
Inside Yes
Types of Biological Nitrogen FixationCyanobacteria
Azospirillum
Rod shaped rhizobia in the nodule of cowpea (Vigna unguiculata).
Azolla
Frankia and Actinorhizal Plants
Actinomycetes (Gram +, filamentous); septate hyphae; spores in sporangia; thick-walled vesicles
Ecology of nitrogen-fixing bacteria
Significance of Biofertilizer:Biological N-fixation (BNF): 69% of global N-fixation. Legume-Rhizobium
symbiosis is the most significant as it supplies 80-90% of the total N reqt. of legumes, increases grain yield by 10-15% (Verma and
Bhattacharyya, 1990). Rhizobium bacteria can fix 50-100 kg N/ha/yr.
Azotobacter and Azospirillum inoculation on several non-legumes crops experienced 5-15% yield increase and N contribution about 25 kg/ha.
Use of Azospirillum as seed inoculant can save 20-30 kg N/ha in crops like Barley, Sorghum and Millets (Subba Rao et al., 1980)
Use of Blue Green Algae provides 25-50 kg N/ha to rice crop (submerged condition)
The use of Phosphobacterin has been found to increase the efficiency of ground rock phosphates and superphosphates applied in in neutral to alkaline soils
Vesicular-Arbuscular Mycorrhizae (VAM) has prominent role in P availability.
Merits/ advantages/ usefulness of Biofertilizer useReqd. in smaller quantities. 1g carrier of a BF contain 10 million cells of
a specific strain (500g/ha material may be sufficient)
Tandon (1991) reported estimates of Nutrient equivalent potential as follows:
Rhizobium: 19-22 kg N/ha
Azotobacter and Azspirillum: 20 kg N/ha
BGA: may fix 20-30 kg N/ha
Azolla : may fix 3-4 kg N/ton of Azolla
BF increases the yield : 10-30 % by supplying N in the soil, adding organic matter to the soil.
Bio fertilizers provides residual effect on soil fertility
BF like Azospirillum and phosphobacterin produce growth promoting substances like hormone, vitamin etc favouring root growth.
The fixed P become available by the application of phosphobacterin and the demand of P to the plants meets accordingly.
Class-8
legume
rhizobia
Fixed nitrogen(ammonia)
Fixed carbon(malate, sucrose)
Rhizobium:
A bacteria having the capacity to form morphologically well defined nodules on the roots of leguminous plants
Gram negative
Short rod 1.2-3.0 μm (L) x 0.5-0.9 μm (B)
Have flagella (single polar or peritrichous
Do not form endospore
Aerobic, mesophilic , Chemoorganotroph
2 types of growth habit : Fast and slow (Bradyrhizobium)
2 distinct type of colony colour: Pink and creamy white Rhizobium has been placed in Bergey’s Manual of Systematic Bacteriology (1984) , belongs to the family Rhizobiaceae
Rhizobium, Bradyrhizobium and Azorhizobium
Azorhizobium ( stem nodule of Sesbania rostrata) A. caulonodans
Buchanon (1926) Rhizobium
Nodule Size: max. 6 cm
Shape: spherical, elongated, palmate
Colour of nodule: white, green , black, pink
Pink colour is effective strain: leghaemoglobin. 15-17kd, 1 peptide bond
Cross section of nodule:
epiderm
cortex
Meristem
Central zone having bacteriods
Vascular bundle
Nodulation process:
1. Pre-infection:(i) Multiplication in rhizosphere
(ii) Attachment of root surface
(iii) Branching of root hair
(iv) Root hair curling
2. Infection and
nodule formation
(v) Formation of infection thread
VI. Nodule development
VII.Releasing Rhizobia from Infection thread
VIII. Bacteriod formation
IX. Reduction of N2 to NH3
X. Complementary functions
XI. Nodule persistence
3. Nodule function
Lectin
Saccharide receptor
R. trifoliiRoot
hair
Model developed by Dazzo and Hubbell, 1975
Root exudates like flavonoids and iso-flavonoids stimulate ‘Nod-d’ whose product binds with ‘nod-box’ which activate other nodulating genes
Lectin = glycoprotien
For nodulation to take place there has to be a molecular dialogue between the plant and the bacterial partner.
Flavonoids
nod genes
Nod factors
•Root hair deformation
•Membrane depolarization
•Induction of early nodulin expression
•Formation of nodule primordia
•etc
The Colonization Process
Signaling• Rhizobia sense flavonoid compounds release by roots• specific species sense particular flavonoids specific to a
plant• Rhizobia move by use of flagella propelling cell through
soil water• Rhizobia produce lipo-oligosaccharides or nod factors
• these initiate root hair deformation and curling and the division of cortical cells in the root at very low concentrations (< 10-9 M soil solution).
Flavonoids secreted by the root of their host plant help Rhizobia in the infection stage of their symbiotic relationship with legumes like peas, beans, clover, and soy.
Rhizobia living in soil are able to sense the flavonoids and this triggers the secretion of Nod factors, which in turn are recognized by the host plant and can lead to root hair deformation and several cellular responses such as ion fluxes and the formation of a root nodule.
a) Plant excrete certain flavonoid compounds (differ between plants) b) Rhizobia recognize certain flavonoids (gene nod D product is a sensor) c) If Nodulin protein (product of nodD genes) recognizes right flavonoids, switch of other nod genes on, and products of nod genes coded proteins are formed--Nod factors (oligochitin compounds) d) Plant, in return, recognize right Nod factors.
Early processes of nodulation is triggered by Nod factors. e) In addition to Nod factors, extracellular polysaccharides of bacteria may function in recognition of bacteria at later process of nodulation (bacteria spreading inside plant cells)
Sequence of molecular communication
nod genes: nodulation, nif genes: common with free-living nitrogen fixation, fix genes; Unique to symbiotic nitrogen fixation
Nodule development process
1. Bacteria encounter root; they are chemotactically attracted toward specific plant chemicals (flavonoids) exuding from root tissue, especially in response to nitrogen limitation
daidzein (an isoflavone)
naringenin(a flavanone)
2. Bacteria attracted to the root attach themselves to the root hair surface and secrete specific oligosaccharide signal molecules (nod factors).
nod factorN-acetylglucosamine
Nod factors structurally arelipochitooligosaccharides (LCOs) that consist of an acylated chitin oligomeric backbone with various functional group substitutions at the terminal or non-terminal residues.
Nod gene expression is induced by the presence of certain flavonoids in the soil, which are secreted by the plant toattract the bacteria.[1] These chemicals induce the formation of NodD, which in turn activates other genes involved in the expression of nod factors and their secretion into the soil. Nod factors induce root-hair curling such that it envelops the bacterium.
This is followed by the localized breakdown of the cell wall and the invagination of the plant cell membrane, allowing the bacterium to form an infection thread and enter the root hair. The end result is the nodule, the structure in which nitrogen is fixed. Nod factors act by inducing changes in gene expression in the legume, most notable the nodulin genes, which are needed for nodule organogenesis.[
From Hirsch, 1992.New Phyto. 122, 211-237
Rhizobium
Formation ofnodule primordia
Bacteroiddifferentiation
Nitrogenfixation
Nod factor(specificity)
Invasion through infection tube
Attachment and infection
Flavonoids(specificity)
3. In response to oligosaccharide signals, the root hair becomes deformed and curls at the tip; bacteria become enclosed in small pocket.
Cortical cell division is induced within the root.
4. Bacteria then invade the root hair cell and move along an internal, plant-derived “infection thread”, multiplying, and secreting polysaccharides that fill the channel.
Rhizobium cells expressing GFP (green fluorescentprotein) invade a host root hair
infection thread
5. Infection thread penetrates through several layers of cortical cells and then ramifies within the cortex. Cells in advance of the thread divide and organize themselves into a nodule primordium.6. The branched infection thread enters the nodule primordium zone and penetrates individual primordium cells.7. Bacteria are released from the infection thread into the cytoplasm of the host cells, but remain surrounded by the peribacteroid membrane (PBM).
Failure to form the PBM results in the activation of host defenses and/or the formation of ineffective nodules.
peribacteroidmembrane
bacteroid
transporters
The Colonization Process• Infection Thread
– Protein called recadhesin and polysaccharides from Rhizobia and lectins from plants interact to adhere the bacterium to the root hair
– curling of the root hair and hydrolysis of root epidermis
– Rhizobia move down centre of the root hair toward the root cortex
– plant produces tube called an infection thread– in the cortex Rhizobia enter enclosed area within a
plant-derived peribacteroid membrane. – membrane protect the rhizobia from plant defense
responses.
8. Infected root cells swell and cease dividing. Bacteria within the swollen cells change form to become endosymbiotic bacteroids, which begin to fix nitrogen.
The nodule provides an oxygen-controlled environment (leghemoglobin = pink nodule interior) structured to facilitate transport of reduced nitrogen metabolites from the bacteroids to the plant vascular system, and of photosynthate from the host plant to the bacteroids.
Nodulation
Bacteriod formation
Shepherd crook
Infection thread
Proliferation of IT
Rhizobium Root Nodules
Bio-chemical considerations
Enzymology of N fixationOnly occurs in certain prokaryotes
• Rhizobia fix nitrogen in symbiotic association with leguminous plants
• Rhizobia fix N for the plant and plant provides Rhizobia with carbon substrates
• All nitrogen fixing systems appear to be identical
• They require nitrogenase, a reductant (reduced ferredoxin), ATP, O-free conditions and regulatory controls (ADP inhibits and NH4
+
inhibits expression of nif genes
Nitrogenase ComplexTwo protein components:
nitrogenase reductase and nitrogenase
• Nitrogenase reductase is a 60 kD homodimer with a single 4Fe-4S cluster
• Very oxygen-sensitive
• Binds MgATP
• 4ATP required per pair of electrons transferred
• Reduction of N2 to 2NH3 + H2 requires 4 pairs of electrons, so 16 ATP are consumed per N2
NitrogenaseA 220 kD heterotetramer
• Each molecule of enzyme contains 2 Mo, 32 Fe, 30 equivalents of acid-labile sulfide (FeS clusters, etc)
• Four 4Fe-4S clusters plus two FeMoCo, an iron-molybdenum cofactor
• Nitrogenase is slow - 12 e- pairs per second, i.e., only three molecules of N2 per second
Why should nitrogenase need ATP ??• N2 reduction to ammonia is
thermodynamically favorable
• However, the activation barrier for breaking the N-N triple bond is enormous
• 16 ATP provide the
needed activation energy
+ 8e- +8H+ + 16 Mg ATP 2NH3+ H2 + 16 Mg ADP+ 16PiN ≡ N
α
α
α
α
β
β
ATP ADP + Pi
e- e-
N2
NH4+
Nitrogenase reductase (Azofer) 60kd
Nitrogenase (Azofermo) 260kd
Nitrogenase enzyme
H2 2H+ +2e-
Hydrogenase ETC
NH4+ produced reacts
with glutamate to form glutamine by combined activities of GS and GOGAT
Stereochemistry of Nitrogenase reaction
Glutamate + +ATP Glutamine + ADP + Pi (H3PO4)
Glutamine + 2-Oxoglutarate 2 Glutamate
NH4+ GS
Mg2+
GOGAT
NADPH + H+ NADP+
Amino acid
Amino acids are transpoted by Xylem
Ubiquinone → cyt b → cyt c → cyta/a3
ADP+ Pi ATP
Nitrogenase
complex
Hydrogen
uptake
H+
N ≡ N
H2
2NH3
Amino acid
e-
Cyt 559-H2
Ferredoxin
Bacteroid
Nodule cytosol
Nodule amino acid pool
Carbon
Photo synthate
e-
TCA cycle
O2
leghaemoglobin
O2
H2O
1
2
3
4
(i) Glutamate + + ATP Glutamine + ADP + Pi (H3PO4)
Glutamine + 2-Oxoglutarate 2 Glutamate
NH4+ GS
Mg2+
GOGAT
NADPH + H+ NADP+
GS= Glutamine synthatse, GOGAT= glutamine Oxo-glutarate amino-transferase
Low km of GS for NH4+ (0.02 mM), high affinity to bind NH4
+
(ii) 2-Oxoglutarate + NH4+ NADPH + H+ Glutamate + NADP+
+ H2O
GDH
GDH= glutamate dehydrogenase, km of GDH for NH4
+ is very high, hence it has low affinity for NH4+
Km is (roughly) an inverse measure of the affinity or strength of binding between the enzyme and its substrate. The lower the Km, the greater the affinity (so the lower the concentration of substrate needed to achieve a given rate).
BacteroidContains less amount of ribosomes, mesosomes than free living
rhizobial cell
Presence of large quantities of PHB (Poly β-hydroxy butyrate) in conspicous amount, nearly 50% of bacteroid consists of PHB
Absence of cytochrome-a in N-fixing bacteroid (about 20-30% dry wt of nodule is due to bacteroid)
Soybean nodule:
A nodule has 3.5 X 104 plant cells
1 plant cell has about 105 bacteroids
So, Number of Bacteroid/ nodule =3.5 x 104 x105 = 3.5 x 109
Again, 1 g root has about 106 cells, So, 1 kg root has about 109 cells
1 kg root-mass may contain bacterial population equivalent to 1 medium sized nodule of Soybean
Class-9
Examples of using the cross-inoculation groups for selecting theproper rhizobial inoculant for the legume host. The proper combination of rhizobia and legume willresult in the best nodulationand most nitrogen fixation. We see that using soybeanrhizobia with soybean formsan effective symbiosis, while soybean rhizobia on leucaena does not. Using information from Table shows that cowpea rhizobia nodulates both mungbean and peanut.
Rhizobium sp. Host Legumes
1. Rhizobium leguminosarum biovar. trifolii Rhizobium leguminosarum biovar. phaseoli Rhizobium leguminosarum biovar. viceae
TrifoliumPhaseolusVicia
2. Rhizobium meliloti Medicago
3. Rhizobium loti Lotus
4. Rhizobium friedii Glycine
5. Rhizobium galegae Galega orientalis
6. Rhizobium huakii Astragalus sinicus
7. Rhizobium tropici Phaseolus vulgaris
Bradyrhizobium japonicum Nodulating soybean
Bradyrhizobium sp. Vigna sinensis
Cross-inoculation group:
A cross inoculation group refers to a collection of leguminous species that are capable of developing nodules when exposed to bacteria obtained from the nodules of any member of that particular plant group
AzotobacterAzotobacter is a free living, aerobic, chemoheterotrophic N fixing bacteria
Important spp: Azotobacter beijerinckii. , A. chroococcum, A.vinelandii
Azotobacter paspalum is closely associated with Paspalum notatum cv batatis. Producing 107 cfu / g of root (colony forming unit)), by ARA, it has been found that it can fix 15-93 kg N/ha/Yr
Azotabacter has protective mechanism to safeguard the nitrogenase enzyme from oxygen.
(i) Respiratory protection in Azotobacter (specialised respiratory system
(ii) conformational protection in Azotobacter
(a phenomena whereby nitrogenase activity becomes reversibly “switched on” or “off” in response to decreased or increased pO2 is known as conformational protection)
Azotobacter inoculants commercially known as Azotobacterin
Slurry of the carrier-based inoculant is made with minimum amount of water and seeds are mixed with the slurry, dried in shade and sown. Seedling dip (10-13 min) in slurry is done for transplanted crops and planted immediately.
Azotobacter have a full range of enzymes needed to perform the nitrogen fixation: ferredoxin, hydrogenase and an important enzyme nitrogenase. The process of nitrogen fixation requires an influx of energy in the form of adenosine triphosphate (ATP). Nitrogen fixation is highly sensitive to the presence of oxygen, and therefore Azotobacter developed a special defensive mechanism against oxygen, namely a significant intensification of metabolism that reduces the concentration of oxygen in the cells.[40] There is also a special nitrogenase-protective protein called Shethna, which protects nitrogenase and is involved in protecting the cells from oxygen. Mutants not producing this protein, are killed by oxygen during nitrogen fixation in the absence of a nitrogen source in the medium.[41]
Homocitrate ions play a certain role in the processes of nitrogen fixation by Azotobacter
AzospirillumAzospirillum could be isolated from the root of tropical grass
Digitaria decumbens (Dobereiner and Day, 1976)
Ubiquitious in nature, capable of forming colony in roots and stems
Gram negative, motile, vibroid in shape, contain Poly β-hydroxy butyrate granules, mesophilic but can tolerate 30-400C
Azospirillum lipeoferum (C4- Maize, sorghum, tropical forages D d are host plant) can fix 30 kg N / ha / yr
Azospirillum brasilense (C3- Rice/ wheat )
Azospirillum culture known to increase root biomass of rice and wheat (Dewan and Subba Rao, 1979)
Produce growth hormones in pure culture (Tien et al, 1982).
Seed inoculation with VAM together with Azospirillum brasilense increase the yield and P content of barley and pearl millet
(Subba Rao et al., 1985)
Carrier: FYM, FYM + soil, FYM + Charcoal
Blue Green Algae:
Ubiquitious in distributionSingled cell or consists of branched/ unbranched filaments
possesses specialised type of cell- Heterocyst (where N fixation occurs)
Important species are Anabaena, Aulosira , NostocIn submerged rice fields bnf is essentially an algal process, contributing 30 kg N/ha
Symbiotic association between floating aquatic fern, Azolla and its partner Anabaena azollae (BGA) forms Azolla-Anabaena complex
Anabaena is contained endophytically in ellipsoidal cavities of aerial dorsal lobes of the fern.
Mature heterocysts have an almost normal content of Chlorophyll a, but are devoid of phycobiliprotein, the principal antenna pigment of Photosystem II
Due to lack of PS-II and ribulose-bis phosphate Carboxylase; they can neither fix CO2 nor produce O2 in light
The lack of photosynthetic O2 generation coupled with H dependent respiration, pO2 becomes very low
Keto acids
Amino acids
glu
α KG
glu
gln gln
glu
N2
NH3FdOxid
Fd red
Electron donor
Oxidised pdt.
ATPADP
Oxygenic
photosynthesis
Vegetative cell Heterocyst
Electron donor
Oxidised pdt.
Microplasmadesmata channel
PS1
Biochemical pathway of N fixation in BGA gln = glutamine; glu = glutamate
Biofertilizer Function/Contribution Limitation Target Crops
Rhizobium Fixation of 50-100 kg N/ha 10-35% increase in yield,
leaves residual N
Fixation only with legumes, Visible effect not reflected in traditional area, Needs optimum P , Mo
Pulse Legumes Oilseed Legumes Forage legumes Tree legumes
Azotobacter Fixation of 20-25 kg N/ha 10-15% increase in yield,Production of growth
Promoting substances
Demands high organic matter
Wheat, maize, cotton, mustard, vegetable crops
Azospirillum Same Poor performance in winter crops
Sorghum. Pearl millet minor millets, maize, rice sugarcane
Blue Green Algae and Azolla
Fixation of 20-30 kg N/ha(BGA):- 30-100kg N/ha F (Azolla)
10-15% increase in yield
Effective only in submerged rice Demands bright sunlight Survival difficult at high temp.
Flooded rice
Phosphate Slubilisers
5-50% increase in yield - All crops
A profile of different biofertilizers
Bio-superIt is a granular material containing raw rock phosphate and finely ground elemental sulfur. The product is inoculated with sulfur-oxidizing bacteria Thiobacillus thiooxidans to ensure the conversion of the sulfur to sulfuric acid. The acid in turn reacts with the phosphate rock and making the contained phosphorus more available to plants.
IARI-Microphos Culture
Gaur and Gaind (1984) developed improved techniques for isolation of rock phosphate solubilizing microorganisms and by systematic investigation new efficient bacteria such as Pseudomonas striata, Bacillus polymixa and fungi like Aspergillus awamori have been selected for preparation of carrier based inoculation known as IARI-microphos culture (Tilak, 1991).
Phosphate Solubilising Micro-organisms :
Bacillus, Pseuduomonas, Brevibacterium,
Corynebacterium, Flavobacterium, Micrococcus,
Sarcina, Achromobacter, Streptomyces,
Schwanniomyces, Aspergillus, Penicillum etc.
Phosphobacterin: Bacillus megatherium var phosphaticum
Release about 10-25 kg P2O5/ha/season
Around 1350 t/a currently used in India
Biofertilizers
General Dosages :
For Paddy - 3 kg/ha
For pulses, oilseeds, vegetables etc. - 2 kg/ha
For fruit and plantation crops - 8-10 kg/ha
Biofertilizers(BF)
Applications Methods : Seed Treatment (200 g(BF) in 400 ml water, make
slurry, mix with seed, dry in shade and sown to the field)
Seedling Root Dipping (200 g(BF) in 1-1.5 L water, dipping root seedling for 30 min to 1 hr.)
Veg. Propagule treatment (200 g(BF) in 4-5 L water , spray it) (Potato, sugarcane,ginger-100 no. propagule)
Soil Treatment (2 kg Bf are mixed in 100 kg Compost, keep it overnight mixture is incorporated in the soil at the time of sowing or planting)
Wheat, Maize, Cotton, Mustard etc. Azotobacter + PSM at 200 g each per 10 kg of seed as seed treatment
For transplanted rice, the recommendation is to dip the roots of seedlings for 8 to 10 hours(whole night) in a soln of
Azospirillum + PSM at 1kg each in 40L water
Jute, Azospirillum+PSM 200g each as seed treatment
Vegetables like Tomato, Brinjal, Chilli, Cabbage, Cauliflower etc., Mustard, Sunflower, Cotton use Azotobacter/ Azospirillum + Phosphobacterin 1 kg each as seedling root dip.
For Potato, Ginger, Colocasia, Turmeric, Paddy -use Azospiillum/ Azotobacter +PSM @ 4 kg each/acre mixed with compost and applied as soil treatment.
Sugarcane use Acetobacter + Phosphobacterin 4 kg each/ acre as seed sett dipping.
Plantation crops use Azotobacter+phosphobacterin 4 kg each/ acre with compost & applied in soil in
two splits per year.
Chickpea seeds before (left) and after (right)
treatment with biofertilizer
Mother culture
Flask culture
Bottle culture
Fermentor broth
Carrier Powder
Neutralization (lime)
Sterilisation (γ-irradiation)
Prepared carrier
Mixing @3:7 , moisture 40-50% (in trays)
Curing (2-7 sprays at 28-30°C)
Packing
Product for despatch (storing at 15-30°C)
Mass production of biofertilizer
What precautions one should take before using biofertilizers?
•Biofertilizer packets need to be stored in cool and dry place away from direct sunlight and heat.
•Right combinations of biofertilizers have to be used. •Other chemicals(Fertilizers and pesticides) should not be
mixed with the biofertilizers.• Seed treatent chemicals like Bavistine etc. should mix 3 days
prior to mix with biofertilizer treatment.•Sow the treated seeds(with Bio fertilizer) immediately preferably in the morning or afternoon avoiding scorching sunlight•The packet has to be used before its expiry, only for the specified crop and by the recommended method of application.
Biofertilizer – BCKV PSB Trichoderma
Phosphate Solubilizing Microorganisms (PSM)
Several soil bacteria & fungi secrete organic acids & lower the pH in their vicinity to bring about dissolution of bound phosphate in soil.
e.g.- Bacillus polymyxa
Pseudomonas striata
Aspergillus awamori
PGPR (Plant Growth promoting Rhizobacteria)
Genera :Bacillus, Pseudomonas, Actinoplanes, Alcaligenes, Arthrobacter, Enterobacter, Azotobacter, Azosprillum, Clostridium etc.
Activities :
Enhanced nutrient uptake
Hormone production
Vitamin production
Enzyme production
Biocontrol
Why biofertilizers are not so popular?
Inspite of several long lasting benefits the bio-inoculants are not very popular among the farming community. There may be several reasons for this, however some of the important ones are as given below:
• Nutrient contribution is dependent on survival of organisms.• Soil with high nutrient status do not show instant visible benefits.• Low carbon content of soils- low proliferation.• Water scarcity -possibility of desiccation.• Fluctuating soil pH- variable microflora.• Extreme temperature -in summer months.• Shelf life of organisms.• Poor storage and transportation• Lack of awareness.• Eagerness to look for instance effects.
If a way could be found to mimic nitrogenase catalysis(a reaction conducted at 0.78 atmospheres N2 pressure and ambient temperatures), huge amounts of energy
(and money) could be saved in industrial ammonia production.
If a way could be found to transfer the capacity to form N-fixing symbioses
from a typical legume host to an important non-host crop species such as corn or wheat,
far less fertilizer would be needed to be produced and applied
in order to sustain crop yields
The Dream…..
Azolla - the untold story
• Signals early in infection– Complex handshaking between legume
root and rhizobium
Incorrect signal
Correctsignal
Genetics of NitrogenaseGene Properties and function
nifH
nifDK
nifA
nifB
nifEN
nifS
fixABCX
fixK
fixLJ
fixNOQP
fixGHIS
Dinitrogenase reductase
Dinitrogenase
Regulatory, activator of most nif and fix genes
FeMo cofactor biosynthesis
FeMo cofactor biosynthesis
Unknown
Electron transfer
Regulatory
Regulatory, two-component sensor/effector
Electron transfer
Transmembrane complex
ba
ab
Fe Protein Fe-Mo Protein Regulation
ba
ab
Fe Protein Fe-Mo Protein Regulation
NtrC-RNA polymerase
Activation of NifA
ba
ab
Fe Protein Fe-Mo Protein Regulation
Electron Transport
Ferredoxin
ATP
ba
ab
Reduced Fe Protein
Fe-Mo Protein Regulation
Electron Transport
Ferredoxin
ATP
ba
ab
Reduced Fe Protein
Fe-Mo Protein Regulation
Electron Transport
Ferredoxin
ATP
Reduction of
ba
ab
Reduced Fe Protein
Fe-Mo Protein Regulation
Electron Transport
Ferredoxin
ATP
Reduction of
Electrons Donated to N2
ba
ab
Reduced Fe Protein
Fe-Mo Protein Regulation
Electron Transport
Ferredoxin
ATP
Reduction of
Electrons Donated to N2
Formation of NH3
NN
2NH3pyruvate + CoA
acetyl-CoA + CO 2
NifJ NifF
NifH
NifD
NifKNifD
NifK
NITROGENASE
NifH
+H2
reducing equivalents
ATP
ADP
Genetics of Nitrogenase Summary
Bio-technological considerations
Redrawn from www.asahi-net.or.jp/~it6i-wtnb/BNF.html
Nitrogenase enzyme complex
Physical association of nif genes in Klebsiella pneumoniae
NitrogenaseMoFe protein
Fe proteinElectron transport
AssemblingFe-Mo-Cofactor
Regulator
H D K T Y E NX U SVWZM F L A B QJ
Rhizobia and the cross-inoculation groups of legumes they nodulate.
Soybean nodules Stem nodules of Aeschynomene afraspera
Short Test on 30th July, 2012at 1.30 p.m.
Total Marks: 20Time: 30
No. of questions: 40
VAM (Endomycorrhiza):
The hyphae often form swellings (vesicle) and minute branches (arbuscles) within the cell of the host
Genera :Glomus, Gigaspora, Acaulospora, Sclerocystis
Activities : (Hacskaylo, 1972) P - Uptake (15-30 kg/ha/season)
Availability of K, Mg, S, Fe, Mn, Zn, Cu, etc.
Tolerance to adverse env. Stresses (draught resistance)
Tolerance to disease and Nematodes
Produce plant growth hormonesDual inoculation: when VAM is mixed with Rhizobium to inoculate legume plant, it is known as Dual inoculation------better (i) nodulation, (ii) N-fixation
and (iii) P-uptake
Vesicular Arbuscular Mycorrhiza
Inside root• Intercellular mycelium• Intracellular arbuscule
• tree-like haustorium• Vesicle with reserves
Outside root• Spores (multinucleate)• Hyphae
•thick runners•filamentous hyphae
Form extensive network of hyphaeeven connecting different plants
(i) Glutamate + + ATP Glutamine + ADP + Pi (H3PO4)
Glutamine + 2-Oxoglutarate 2 Glutamate
NH4+ GS
Mg2+
GOGAT
NADPH + H+NADP+
GS= Glutamine synthatse, GOGAT= glutamine Oxo-glutarate amino-transferase
Low km of GS for NH4+ (0.02 mM), high affinity to bind NH4
+
(ii) 2-Oxoglutarate + NH4+ NADPH + H+ Glutamate + NADP+
+ H2O
GDH
GDH= glutamate dehydrogenase, km of GDH for NH4
+ is very high, hence it has low affinity for NH4+
(i) Glutamate + + ATP Glutamine + ADP + Pi (H3PO4)
Glutamine + 2-Oxoglutarate 2 Glutamate
NH4+ GS
Mg2+
GOGAT
NADPH + H+NADP+
GS= Glutamine synthatse, GOGAT= glutamine Oxo-glutarate amino-transferase
Low km of GS for NH4+ (0.02 mM), high affinity to bind NH4
+
(ii) 2-Oxoglutarate + NH4+ NADPH + H+ Glutamate + NADP+
+ H2O
GDH
GDH= glutamate dehydrogenase, km of GDH for NH4
+ is very high, hence it has low affinity for NH4+
Sinorhizobium meliloti Bacteroids
Glutamine and glutamate are usually at much higher concentrations than other amino acids in cells.
This is due to their role as nitrogen carriers.
Glutamate synthase (bacteria and plants)
Glutamine can combine with a-ketoglutarate to yield a pair of glutamates. This is a reduction, catalyzed by glutamate synthase.