Role of PGPR in sustainable agriculture

1. Credit Seminar on
Role of PGPR in
Sustainable Agriculture
Presented By…
Prince Kr. Gupta
M.Sc(Ag) 3rdSemester
DEPARTEMENT OF PLANT PATHOLOGY

2. WHY? ?
Rapid increase of human population ( Global Problem)
Food, the basic requirement
So, how do we get food?
Increase agriculture land- Limited resource
Greater use of chemicals- Against eco friendly approaches
More farm mechanization- Expensive
Use of Plant growth promoting Rhizobacteria- YES!!

3. The term PGPR was first used by Kloepper and Schroth (1978).
• PGPR are a group of naturally occurring beneficial soil bacteria,
mainly present in the rhizosphere at root surfaces and have the
capability to stimulate plant growth Kloepper and Schroth (1978).
• Rhizosphere ( Greek word rhiza, meaning root). region outside the
root and a dynamic zone for microbial activities because of nutrients
secreted by plant roots in the form of soluble exudates such as
amino acids, organic acids etc.
• Several PGPR are Azotobacter, Acetobacter, Azospirillum,
Bacillus, Pseudomonas, Rhizobium etc.

4. CLASSIFICATION OF PGPR
1. Extracellular (ePGPR) .
2. Intracellular (iPGPR) .
• The ePGPRs may exist in the rhizosphere or in the spaces
between the cells of root cortex.
Agrobacterium, Azotobacter, Azospirillum,
Bacillus, Pseudomonas and Serratia
• The iPGPRs locates generally inside the specialized nodular
structures of root cells.
Bradyrhizobium,
Mesorhizobium and Rhizobium.

5. Pseudomonas
AzotobacterAzospirillum
Bacillus Rhizobium
Burkholderia
Microscopic Photographs of Different Genera of PGPR

6. Arthrobacter SerratiaEnterobacter
KlebsiellaGluconacetobacter Streptomyces
Microscopic Photographs of Different Genera of PGPR

7. • Ideal PGPR should be..
Possess high rhizospheric competence.
Enhance plant growth capability.
Broad spectrum of action.
Safer for environment & humans.
Compatible with other rhizobacteria.
Tolerant to heat, uv radiation.

8. Benificial and Harmful Aspect of PGPR
Increase of nitrogen fixation in crops.
Increasing the availability of other nutrients like phosphate,
sulfur, iron and copper.
Producing plant hormones such as auxins, ethylene, gibberellins,
abscisic acid (ABA), and cytokinins.
Controlling pests and plant diseases.
Increase the drought tolerance & water use efficiency.
Maintaining soil fertility.

10. • Effectiveness of auxin produced by PGPR relies upon its
concentration. For instance, at low concentrations, it enhances
plant growth, whereas at a high level it inhibits root growth.
• Rhizobitoxine produced by Bradyrhizobium elkanii is an
inhibitor of ethylene synthesis, it can alleviate the negative
effect of stress-induced ethylene production on nodulation but
it also considered as plant toxin because it induces foliar
chlorosis in soybeans.

12. Mechanism of PGPR

13. 1. Nitrogen Fixation…
Direct Mechanism….
• Nitrogen fixation is the conversion of atmospheric nitrogen into utilizable
nitrogen that changes to ammonia which is essential for plants.
• The process of N2 fixation is carried out by a complex enzyme, the
nitrogenase complex. Structure of nitrogenase was elucidated by
Dean and Jacobson (1992) as a two-component metalloenzyme.
(i) Dinitrogenase reductase (ii) Dinitrogenase.
• Dinitrogenase reductase provides electrons with high reducing power while
dinitrogenase utilizes these electrons to reduce N2 to NH3.

14. • Symbiotic nitrogen fixation- Mutual relationship between microbes
& the plant. eg. Rhizobium, Bradyrhizobium sp.
• .
• Non-symbiotic nitrogen fixation- carried by Azoarcus sp,
diazotrophicus, Herbaspirillium sp, and Azotobacter sp.

16. Isolates Nodules/pla
nt
At 45 DAS
Root length/
palnt
Biomass/ plant Pod /
plant(g)Root (g) Shoot (g)
Baccillus sp.(NN) 122 41.0 2.17 16.68 4.70
Beijerinkia sp.(B17) 125 43.0 1.98 6.20 4.70
Pseudomonas sp.(M-13) 120 41.0 1.88 14.62 4.32
Pseudomonas sp.(BHU1) 166 46.0 2.29 19.54 5.24
Arthrobacter sp (9) 77 31.7 1.68 11.26 2.81
Strain A15 121 43.0 2.17 15.60 4.54
Strain A18 130 43.0 2.13 15.23 4.59
Strain A 19 163 44.0 2.20 18.34 5.14
Control 110 38.8 1.82 14.29 4.30
SE ±6.3 ±2.2 ±0.16 ±1.40 ±0.31
CV(%) 5.9 6.5 8.8 10.1 8.4
Table no.1. Effect of plant growth / nodulation promoting rhizobacteria on the
nodulation, growth and yield of groundnut cultivars JL 24
(Pal et al., 1998)

17. 2. Phosphate solubilization…
• Phosphorus is essential nutrient for optimum growth.
• Phosphorus mostly present in insoluble forms
• Plants absorb phosphorus only in two soluble forms,
Monobasic ( H2PO4
-) and Dibasic ( HPO4
2-) ions.
Phosphate solubilizing bacteria are :
Azotobacter, Bacillus, Pseudomonas, Rhizobium and Serratia
Mechanism:
• Release of complexing or mineral dissolving compounds
• Liberation of extra cellular enzymes.
• By means of phosphatases that help to unbind the phosphate groups from
organic matter.

18. (Aftab Afzal et al., 2008)

19. 3. Siderophores Production…
• Siderophores (Greek: "iron carrier") are low molecular weight iron binding
protein released by microbes to scavenge iron from avaialable mineral
phases by the formation of soluble Fe complexes.
• Siderophores are usually stable complexes and can be of different types such
as hydroxamates, phenolcatecholates and carboxylates.
• In case of stresses such as heavy metal pollution, siderophores help the
plants to bear these stresses.
• Siderophores produced by Pseudomonas spp.,
Alkaligenes, Bacillus, Enterobacter etc.
implicated in the biological control of several diseases.

21. 4.Phytohormone Production…
 Phytohormones are the chemical messengers that occur in low concentration.
It play role in formation of leaf, flowers and ripening of fruit and decrease the
negative effects of the environmental stress.
 PGPR can alter phytohormone levels and thereby affects the plant’s hormonal
balance. Different type of phytohormone are..A. Indole acetic acid
• Helps in cell division, cell elongation, differentiation and extension.
• IAA promote growth of auxiliary bud and bud formation.
• Pseudomonas,Rhizobium, Bradyhizobium, Agrobacterium etc are IAA
producing PGPR.
• Stimulates seed and tuber germination.
• Biosynthesis of various metabolites & resistence to stressful condition.

22. B. Ethylene
• Ethlene a gaseous hormone produced by plant
• Formed by breakdown of methionine present in all the cells.
Available in two form- i) Ethrel- liquid form used in banana fruit ripening
ii) Ethephone- gaseous form used in ripening of
sugarcan, wheat, coffee.
• 1-aminocyclopropane-1-carboxylate (ACC) deaminase enzyme present in
PGPR regulates ethylene production by metabolizing ACC into alpha-
ketobutyrate and ammonia. Inoculation with PGPR combined with ACC
deaminase will be quite helpful in promoting plant growth under stress conditions
by reducing stress-induced ethylene production. And known as “stress
ethylene”.
• Bacterial strains exhibiting ACC deaminase are :
Agrobacterium, Azospirillum, Bacillus, Enterobacter, Pseudomonas,
Ralstonia and Rhizobium.

23. Fig. 1
Ethylene production from
Mithionine
Fig.2

24. C.Cytokinins and gibberellins
• Cytokinins are phytohormones that promote cell division .
• It help in dormancy breaking, root development, accumulation of
chlorophyll, leaf expansion, etc.
Azotobacter, Azospirillum, Rhizobium, Bacillus, and Pseudomonas spp.
• Gibberellin help in cell elongation and increase fruit size &fruit senescence.
• Gibberellins act as a chemical messenger and help by breaking dormancy.

25. Potassium Solubilization….
• Potassium (K) is the third major essential macronutrient for plant growth.
• The concentrations of soluble potassium in the soil are usually very low.
• Plants shows poor develop roots, slow growth ,
produce small seeds and have lower yield in its absence.
• PGPR solubilize potassium rock through production and secretion of organic
acids.
• Pseudomonas, Acidothiobacillus ferrooxidans, Bacillus mucilaginosus, Bacillus
edaphicus, B. circulans etc.

26. Antibiotic mechanism of PGPR limit the pathogens invasion in the plant tissue.
Antibiotic - Tropalone, phenazine.
Bacillus, Streptomyces strains produce antifungal metabolites such as
oligomycin-A, xanthobaccin, kanosamine and fengycin etc.
• PGPR synthesizing the lytic enzymes such as chitinases, cellulases, 1,3-
glucanases, proteases, and lipases that can lyse cell walls pathogenic fungi
Production of rhamnolipid causing lysis of plasma membrane of zoospores fungi.
1.Antibiotic production and lytic enzymes
Indirect Mechanism….

27. 2.Induced systemic response (ISR)..
• ISR may be defined as a physiological state of enhanced
defensive capacity elicited in response to specific
environmental stimuli and consequently the plant’s innate
defenses are potentiated against subsequent biotic challenges.
• ISR involves jasmonate and ethylene signaling which
stimulate the host plant’s defense responses to a range of
pathogens.

29. 3.Exopolysaccharide Production….
• These are in the form of hydrated gels around the cells and help in root
colonization.
• EPS produced by rhizobacteria, enter aggregate soil and alter its porosity thus,
the porosity of the soil, which is directly related to soil water transferred to the
roots, is partly controlled by bacterial activity.
• Effective colonization of plant roots by EPS-producing microbes helps to hold
the free phosphorous and circulating essential nutrient to the plant.
• EPS producing microbes constitute protection against stress, attachment to
surfaces plant invasion, and plant defense response in plant–microbe interactions.

30. PGPR acts as a biofertilizers
• Vessey (2003) defines biofertilizer as a substance which contains living
microorganisms which, when applied to seed, plant surfaces, colonizes the
rhizosphere promotes growth by increasing availability of nutrients.
• Biofertilizers natural mechanism..
Solubilizing phosphorus , Nitrogen fixation and
Synthesis of plant growth promoting substances.
Microbes present in biofertilizers increase the soil natural nutrient cycle.
• Biofertilizer is being cheaper and safer than chemical pesticides.

31. PGPR acts as a rhizoremidiator
Rhizoremediation, the degradation of contaminants in the rhizosphere.
Rhizoremediation most potential approach for PAHs remediation in soil
PGPR produce 1-aminocyclopropane-1-carboxylic acid deaminase and growth hormones
to overcoming the challenge of plant stress like excessive ethylene production.
Biosurfactant, enhancing PAHs Rhizoremediation:
1.Wetting and penetrating actions,
2.Spreading
3.Microbial growth enhancement
4.Anti-microbial actions.
Advantages :
Biodegradability
Low toxicity
Biocompatibility and Digestibility
Availability of raw materials

32. HCN Production By PGPR
• The deleterious Rhizobacteria act as biocontrol agents of weeds that can colonize
plant root surfaces and are able to suppress plant growth.
• Cyanide being toxic is produced by most microorganisms including bacteria,
algae, fungi and plants as a means of survival by competing with the
counterparts.
• No negative effect on the host plants.
• HCN synthesized by Pseudomonas and Bacillus species acts as an effective agent
for the biocontrol of weeds.
• HCN is likely to inhibit electron transport chain and energy supply to cell,
leading to death of cells.

33. Strain Lettuce Barnyard grass
Root length
(mm)
%
Reduction
Root length
(mm)
%
Reduction
Pseudomonas sp.42 2.7 85 3.8 83
Pseudomonas sp.74 5.6 68 10.5 54
Pseudomonas sp.473 3.9 78 3.1 86
P. uorescens 297 3.9 78 2.8 88
P. uorescens 126 4.1 77 7.5 67
P. aeruginosa 136 5.1 72 6.5 71
P. uorescens 672 3.8 78 4.6 80
P. syringae 81 15.2 16 18.8 18
P. uorescens 1942 4.6 71 10.6 54
Pseudomonas sp. 1035 5.2 74 3.8 84
Flavimonas oryzihabitans 7511 4.7 5 5.0 78
Control 18.0 22.8
LSD 0.05 0.7 1.6
Table. 03. Effects of HCN produced by various rhizobacteria on seedling root length of
lettuce and barnyardgrass weeds.
(Kremer et al., 2001)

35. Treatments
Shoot
length
(m)
Root length
(m)
Fresh
weight
(kg)
Dry weight
(kg)
Uninoculated watered plant as
control
0.2166±2 0.0366±0.57 0.42766±4 0.17833±7
Plant inoculated with bacteria
and sufficient water supply
0.3066±3 0.0866±1.52 0.53033±6 0.262±5.6
Bacteria inoculated plant under
drought stress
0.19±2 0.12±2.64 0.31866±7 0.132±5.2
Uninoculated plants under
drought stress as control
0.10±2 0.04±1 0.208±4 0.107±4.9
Table.04 . Effect of Pseudomonas fluorescens on growth of
Green gram under water & drought condition.
( Sarma et al., 2015)

36. Isolates Seed
germination %
Seedling
height
(cm)
Shoot dry
weight
(mg/plant)
Root
length
(cm)
Root dry
weight.
(mg/plant)
Control 82.10 10.30 7.20 4.10 5.60
PGB1 90.15 12.30 7.60 4.50 6.40
PGB2 90.26 12.50 8.60 4.30 6.60
PGB3 84.31 11.80 8.00 4.40 6.40
PGB4 94.15 13.80 9.40 5.30 6.80
PGB5 83.97 10.90 7.80 4.60 6.10
PGT1 86.63 12.60 7.60 4.50 6.20
PGT2 92.23 12.00 8.20 4.40 6.60
PGT3 92.00 13.10 9.20 4.80 6.0
PGG1 92.07 12.70 7.60 4.50 6.50
PGG2 92.59 13.20 9.20 5.10 6.60
Significance - ** ** ** **
CV (%) - 4.00 3.57 5.59 4.23
Table.05 .Effects of different PGPR isolates on seed germination
and growth of rice seedlings.
(Ashrafuzzaman.M et al,. 2009)

37. Treatments Plant height
(cm)
Number of
branche/pl
ant
Number
of leaves
Total
biomass
(g/plant)
Chlorophyll
(mg/plant)
Pseudomonas JK-5 + TMV 45.20 9.67 52.0 36.40 1.860
Pseudomonas JJK-18 + TMV 43.20 8.33 47.0 35.10 1.810
Pseudomonas B-36 + TMV
48.10 9.0 52.33 37.33 1.950
Pseudomonas B-15 + TMV
44.30
9.0
49.33 36.23 1.890
Pseudomonas B-25 + TMV 51.13
11.33
59.0 39.27 2.040
Enterobacter E-21 + TMV
43.60 8.0 51.67 35.33 1.820
P.fluorescens NCIM 2099 + TMV
50.43 10.33 57.0 38.63 2.100
Diseased control (only TMV) 35.30 6.67 37.0 25.80 0.790
Healthy control (no PGPR, no TMV)
41.50 8.0 45.67 33.27 1.270
S.Em+ 0.183 0.248 0.484 0.118 0.017
CD @ 1% 0.745 0.769 1.971 0.489 0.070
Table.06. Plant growth parameters of tomato as influenced by inoculation with
plant growth promoting rhizobacterial isolates at 60 DAT
( Kumar et al. 2007)

38. Treatment Fruit Yield
(kg/plant)
N uptake
(mg/plant)
P uptake
(mg/plant)
K uptake
(mg/plant)
Pseudomonas JK-5 + TMV 0.640 271.0 84.88 205.17
Pseudomonas JJK-18 + TMV 0.640 259.67 81.16 198.27
Fluorescent Pseudomonas B-36 + TMV 0.650 276.0 84.84 209.70
Pseudomonas B-15 + TMV 0.640 270.0 84.74 205.67
Pseudomonas B-25 + TMV 0.690 300.73 99.87 234.67
Enterobacter E-21 + TMV 0.630 250.97 75.30 195.00
P. fluorescens NCIM 2099 + TMV 0.670 298.0 97.41 225.30
Diseased control (only TMV) 0.340 168.33 54.13 130.17
Healthy control (no PGPR, no TMV) 0.550 230.17 65.80 180.00
S.Em+ 0.001 1.540 0.729 0.605
CD @ 1% 0.004 6.270 2.970 2.463
Table.07 . Influence of plant growth promoting rhizobacterial isolates on fruit
yield and nutrient uptake by tomato plants at harvest
(Kumar et al. 2007)

39. Mechanisms of Stress-Tolerating PGPR to Promote
Plant Growth in Saline Conditions
Osmoprotectants or Osmotolerance : Azospirillum, Pseudomonas,
Bacillus, Rhizobium.
Aminocyclopropane-1-Carboxylate Deaminase: Rhizobium ,
Pseudomonas .
Auxin Production Stimulating ACC Synthetase rhizobia:
Pseudomonas xuorescens
Exopolysaccharides : Rhizobium
Antioxidative Activity: S. proteamaculans & Rhizobium leguminosarum

40. Rhizosperic Bacteria
Degrades
ROS
ACC
Deanimases
Increase binding
with cation
Antioxidant
(SOD, POX
,CAT)
Increase
accumulation of
Nitrate & Phosphate
Regulates
ACC
Production
Decrease
transloction
of sodium
ions
Increase
Fertility
Lower
ehylene
Production
Proline,
Gutamate
etc
Saline
condition
IAA,
Cytokinin
EPS
Production
Osmoprotec
tants
Osmoprotec
tants
Osmoprotec
tants
Osmoprotec
tants
(Hasna Habib et.al. 2015)

41. Treatments LFW/plant LDW/plant SFW/plant SDW/plant RFW/plant RDW/plant
Non inoculated
T0
2.63±0.13 0.26±0.03 1.57±0.14 0.14±0.02 0.34±0.03 0.04±0.01
UPMR2 (Bacillus
megaterium) inoculated
T1
2.83±0.15 0.28±0.3 1.90±0.08 0.16±0.02 0.47±0.05 0.03±0.00
UPMR18 (Enterobacter
sp.)inoculated
T2
3.92±0.17 0.46±0.01 2.56±0.29 0.28±0.01 0.70±0.08 0.07±0.02
UPMR2 &UPMR18
inoculated
T3
3.28±0.258 0.37±0.01 ±0.07 0.22±0.01 0.65±0.06 0.06±0.00
Table 08. Effect of PGPR inoculation on growth attributes of okra plants under
salinity stress.
(Hasna Habib et.al. 2015)
LFW- Leaf fresh weight; LDW-Leaf dry weight; SFW- Shoot fresh weight
SDW- Shoot dry weight; RFW- Root fresh weight; RDW- Root dry weight

43. Treatments Leaf area
(cm²)
Shoot
length
(cm)
No of fruit /
plant
Fruit
length(cm)
Fruit
yield
(t/ha)
Fruit rot
incidence
(%)
Pf1 16.75 23.78 7.3 8.83 4.41 9.38
B. subtilis 17.07 22.11 6.9 8.69 4.24 9.70
PB 16.41 22.67 6.9 8.67 4.57 9.94
PNC 18.80 24.81 7.6 9.72 5.10 8.60
BNC 18.78 25.06 7.6 9.43 4.63 8.33
PBNC 21.28 28.12 10.2 10.93 6.87 7.28
Carbendazim 15.99 21.68 6.1 7.56 3.79 11.09
control 10.57 17.99 3.8 6.5 3.47 23.02
Table 09.Effect of different PGPR formulations on growth, yield attributes and
fruit rot of chilli infection under field conditions
(Harish.S et al.,2004 )
PBNC:-Psuedomonas fluorescens+Bacillus subtilis+neem+chitin

44. Pseudomo
nas strains
Cercospora theae Phomopsis theae Poriahypolateritia
Linear
growth
On 12th
day(mm)
Inhibition
over
control
(%)
Linear
growth
On 7th
day(mm)
Inhibition
over
control
(%)
Linear
growth
On 21th
day(mm)
Inhibition
over
control
(%)
VP5 24.0 47 33.3 26 15.0 67
CP2 25.3 44 34.6 25 20.7 60
GP4 24.7 45 33.7 24 16.2 64
MP7 35.3 21 37.0 18 20.3 55
VPP3 31.0 32 36.0 20 29.7 34
MPP2 36.0 20 35.7 21 25.3 44
CGP1 28.7 36 35.0 22 21.0 43
CMP3 30.7 32 39.7 15 31.7 30
KP6 30.7 32 34.3 24 16.7 43
Control 45.0 - 45.0 - 45.0 -
SE±
CD at (p=0.05)
4.34
9.08
- 6.37
12.34
- 6.78
11.66
-
Table 11 . Effect of antibiotic potential of P.fluorescens on the growth of tea
pathogen.
(Reddy et al.,2011)

45. Treatments Disease
Incidence(%)
leaffolder
incidence(%)
Yield t/ha
Trail I Trail II Trail I Trial II Trail I Trial II
Pf1 24.44 19.26 15.03 12.62 6.28 4.64
FP7 25.92 22.96 15.88 13.46 6.21 4.55
Pf1+FP7 22.16 17.03 11.60 9.41 6.40 4.80
Pf1+Chitin 22.22 18.51 13.46 11.44 6.32 4.80
FP7+Chitin 23.15 19.26 14.93 10.7 6.33 4.59
Pf1+FP7+Chitin 18.99 16.29 11.26 7.93 6.53 5.04
Carbendazim 19.26 17.77 20.74 13.54 5.98 4.36
Chlorpyriphos 34.05 25.55 4.25 4.83 6.00 4.67
Carbendazim+Chlorpyriphos 19.03 19.25 5.21 3.99 6.19 4.29
Control 53.14 42.96 21.62 18.01 5.80 3.84
Pseudomonas fluorescens strains : Pf1 & FP7
Trial I at Pondi-cherry, India
Trial II at,Coimbatore, India
(Bharthi.M et al.,2002)
Table12. Effect of single and mixture of Pseudomonas fluorescens (PGPR) strains
against sheath blight and leaffolder incidence in rice under field conditions.

46. Dose of antagonist
(g/pot)
Wilt incidence (%)
Trichoderma viride Pseudomonas
fluorescens
Bacillus subtilis
5 66.67 58.33 66.67
10 50.00 41.67 48.33
15 47.22 36.11 40.0
20 41.67 25.00 38.45
25 36.11 25.00 30.89
30 33.33 22.22 31.33
Control 94.45 94.45 94.45
CD (P=0.05) 3.70 3.93 3.70
(Uma Maheswari et al. 2002)
Table 13. Incidence of Jasmine wilt (S. rolfsii) potted plants treated with
commercial formulation of antagonists

47. Commercial Formulation…..

48. Product Targated Pathogen/
Disease
Crop
recommended
Mnaufacture
Bio-save
10,11,100,1000.-
P.Syrinage ESC-100
Botrytis cinereaea,
Penicillium spp.
Pome fruit,
Citrus
Eco Science
Crop, Produce
System Div,.
Blight BanA 506-
P.Fluorscens A506
Erwinia amylovora Almond, Apple,
Cheery, Pear, etc.
Plant Health
Technologies
Subtilex-B.substalis. Fusarium spp, Rhizoctonia
spp& Phythium spp
Ornamental &
Vegetable crop
Becker
Underwood
Bio-yield-
Combination of B.
substalis &
B.amyloliquefaciens
Fusarium spp, Rhizoctonia
spp.
Tomato
Tobacco etc
Gustafson Inc;
InterceptTM-
P.cepacia
Rhizoctonia solani
Fusarium spp
Maize, cotton Soil
Technologies
Corp.
Rhizo-Plus-
B. substalis strain
FZB24
R.solani,Fusarium spp,
Altrnaria spp
Ornamental,
Forest tree
seedling
KFZB Biotechnik
GMBH, Berlin,
Germany.
Table14. Commercial products of PGPR in plant disease
management..
(Nakkeeran et al.,2004)

49. Viable market size, broad spectrum activity is preferable
Safety, no-effecton non-target species.
High performance and consistency, effect has to be
Comparable to that of chemical pesticides.
Cost and practically, use of cheap substrates such as
Agricultural waste for production, stable when dry and be
Easily formulated, insensitive to light and dry climate.
Stability, remains stable and active at-5ºC to +30ºC
Application, should not change the present day
agricultural practices
Requirements for Commercialisation…

50. PGPR , Safe mean of agriculture, Non – toxicity to plant and mammals,
and no effects on non targated plants.
High performance and consistency, effect has to be
Comparable to that of chemical pesticides.
Genetic engineering, improves PGPR strain.
Benificial, in laboratary and green house.
Challenges , like natural variations.
Future Prospects and chanllenges….

51. Conclusion…..
Nitrogen fixation, Increase in plant.
Supply, It increase of other nutrients like Phosphrous.
Sulfur,Iron, Copper etc.
Phytohormones, it produce and enhance the plant growth .
Control, its protect the plant from various diseases.