1. DIFFERENT FORMS OF
PLANT MICROBE – INTERACTIONS
MARUTHI H PATIL
PAMM2006
Ph.D. Scholar
COURSE TITLE:
MOLECULAR BASIS OF HOST-PATHOGEN
INTERACTION
DEPT. OF PLANT PATHOLOGY
2. Fig. Examples of plant-microbe interactions in the rhizosphere. Plant roots release exudates
containing sugars, organic acids, and amino acids that may attract microbes. In exchange,
they protect the plant against pathogens releasing antimicrobial compounds; or increase
nutrient uptake. On the other hand, these carbon-containing compounds can also attract
pathogens. They can compete for nutrients, infect the plant, and affect the rhizosphere
microbial community
4. Plant-Microbe Interactions
Plant-microbe interactions diverse – from the plant perspective:
• Negative – e.g. parasitic/pathogenic
• Neutral
• Positive – symbiotic
Important positive interactions with respect to plant abundance
and distribution –related to plant nutrient and water supply:
1. Decomposition
2. Mycorrhizae
3. N2 fixation
4. Rhizosphere
5. I. Decomposition
A. Raw material or Organic Matter
Soil organic matter derived primarily from plants –
• Mainly leaves and fine roots
In a soil which at first has no readily decomposable materials, adding
fresh tissue under favorable conditions:
1)immediately starts rapid multiplication of bacteria, fungi,
and actinomycetes,
2)which are soon actively decomposing the fresh tissue.
6. B. Processes
1. Fragmentation –
• Breakdown of organic matter (OM) into smaller bits = humus
• By soil ‘critters’– including nematodes, earthworms, springtails, termites
• consume and excrete OM incomplete digestion
nematode
springtail (Isotoma viridis)
7. 2. Mineralization
Plant uptake
Nitrite
NO2
-
Nitrate
NO3
-
energy for
nitrifying
bacteria*
Nitrification
• Breakdown OM inorganic compounds
• Microbial process: accomplished by enzymes excreted into the soil
For Nitrogen
proteins
(insoluble)
amino
acids
energy for heterotrophic bacteria
proteases
Ammonium
NH4
+
Mineralization
* In 2 steps by 2 different kinds of bacteria – (1)
Nitrosomonas oxidize NH3 to nitrites + (2)
8. 4
NH +
mineralization
NO3
-
plant uptake
1) Nitrate (NOpr-o)teins
3
• Preferred by most plants, easier to take up
• Even though requires conversion to NH4
+
before be used lots of energy
N uptake by plants – Chemical form taken up can vary
2) Ammonium (NH4
+ ) –
• Used directly by plants in soils with
low nitrification rates (e.g. wet
soils)
• vs. taking up & storing NH4
+
problematic
• More strongly bound to soil
particles
• Acidifies the soil
9. Symbiotic association between plant roots and fungi.
•Probably the roots of the majority of terrestrial plants
are mycorrhizal.
Type of Mycorrhiza
1. Ectomycorrhiza - In which fungal cells form an
extensive sheath around the outside of the root with
only little penetration into the root tissue itself.
2. Endomycorrhiza - In which the fungal mycelium is
embedded within the root tissue.
II. Mycorrhiza
11. Fungi-Plant Interaction
Mycorrhizae
(root fungus)
Nearly 90% of native
plants have mycorrhiza
association
Mycorrhiza: Symbiotic
relationship between
plants (roots) & soil fungi
- extension of root
system
- fungus enhances
nutrient and water
intake
- plants provide carbon
source
12. Mycorrhizae
- Associations occur exterior root
-Develop on evergreen trees and
shrubs
Ectomycorrhizae
Endomycorrhizae
-Associations occur in root interior
between cells
-Develop on deciduous trees, annual
and herbaceous plants
13. C. Function of mycorrhizae:
1) Roles in plant-soil interface –
a) Increase surface area & reach for absorption of soil water & nutrients
b) Increase mobility and uptake of soil P
c) Provides plant with access to organic N
d) Protect roots from toxic heavy metals
e) Protect roots from pathogens
2) Effect of soil nutrient levels on mycorrhizae
• Intermediate soil P concentrations favorable
• Extremely low P – poor fungal infection
• Hi P – plants suppress fungal growth
– taking up P directly
14. III. N2 Fixation
N2 abundant – chemically inert
N2 must be fixed = converted into chemically usable form
• Lightning
• High temperature or pressure (humans)
• Biologically fixed
The conversion of molecular Nitrogen in to ammonia by
microorganism is called as BNF
Boussingault (1838). Shows that leguminous plant can fix
atmospheric N and increase N content in soil.
Better crop rotation involving legumes plant .
15. 1) Legumes
eg. Peas, Soybeans, Clovers
• Widespread
• bacteria = e.g., Rhizobium spp.
A. Occurs only in prokaryotes:
• Bacteria (e.g. Rhizobium, Frankia)
• Cyanobacteria (e.g. Nostoc, Anabaena)
Free-living in soil/water – heterocysts
Symbiotic with plants – root nodules
Loose association with plants
Examples of plant–N2-fixing symbiotic systems –
Anabaena with heteroc
• Those with N2-fixing symbionts form root “nodules”
soybean
root
16. IV. Rhizosphere
Rhozospere is the soil region in close contact with plant roots
Rhizosphere Components –
1.Rhizosphere- The zone of soil influenced by roots through the release
of substrates that affect microbial activity.
2. Rhizoplane - Surface of the plant roots in the soil. Rhizoplane is the
site of the water & nutrient uptake & the release of
exudates in to the soil.
3. Root Itself - It is the part of the system, because certain endophytic
microorganisms are able to colonize inner root tissues
The rhizosphere effect can thus be viewed as the
creation of a dynamic environment where microbes
can develop and interact. This microorganisms play
important roles in the growth and ecological fitness of
their host.
17. V. Rhizosphere interactions
– the belowground foodweb
Zone within 2 mm of roots – hotspot of biological activity
• Roots exude C & cells slough off = lots of goodies for soil microbes lots of microbes for their
consumers (protozoans, arthropods)
• “Free living” N2-fixers thrive in the rhizosphere of some grass species
Fine root
18. (1) Removing hydrogen sulfide, which is toxic to
the plant roots
(2) Increasing solubilization of mineral nutrients
(3) Synthesizing vitamins, amino acids,auxins,
gibberellins that stimulate plant growth
(4) Antagonizing potential plant pathogens through
competition and the production of antibiotics
Microbial populations in the Rhizosphere
may benefit the plant by:
19.
20. Nitrogen-fixation – convert atmospheric N into useful Nitrogen
(N gas plants animals)
Azotobacter (Aerobic) and Clostridium (Anerobic) genera N
fixer
Decomposition in the biosphere – get rid of dead organisms,
nature’s recyclers
Azotobacter common in Rhizosphere maintain roots exudates.
Genetically-engineered bacteria produce insulin and other
important chemicals.
Can also help clean up oil spills: oil ‘eating’bacteria
Organisms present will depend on many factors Nutrients, O2,
moisture, pH, Eh, microhabitats.
21. Fungi
• Decompose carbon
compounds
• Improve OM accumulation
• Retain nutrients in the soil
• Bind soil particles
• Food for the rest of the
food web
• Mycorrhizal fungi
• Compete with plant
pathogens
22. ALGAE
• Algal Population Imp for soil fertility
• In barren soil it can bind soil partical
• To fix atm. N symbiotically or asymbiotically.
• Population is smaller than bacteria and fungi.
Mostly they are present on surface or subsurface of
the soil.
. BGA used reclamation o akaline soil.
• The cyanobacteria play a key role in the
transformation of rock to soil are Eukaryotic Found
in fresh and salt water environments
• Can live on rocks, trees, and in soils with enough
moisture
• Can carry on photosynthesis – produce large
amount of oxygen
• Diatoms, Clamydomonas, Volvox, Spirogyra
23. Actinomycetes
Mostly abundant in surface soil.
In soil pH high population very high
Take part in decomposition of OM-most active
decomposer. eg.- Streptomyces and Nocardia
decomposer of cellulose in soil.
Act as plant pathogen eg. Potato scab disease
(Streptomyces scabies )
Streptomyces alini is associated in root nodule of
Alder plant for N fixation.
Antibiosis; Some spp. Of Strptomycesare capable of
synthesizing antibiotic. eg: Streptomycin,
Chloromphenicol, Cyclohexiamide
24. Important group of microbes and their roll in
fertility of soil and plant growth.
Microbes Type Numbers / gram
Bacteria 2,50000000 2.5 X 108
Fungi 700000
7.0 X 105
Actinomycetes 400000 4 X 105
Algae 50000 5 X 104
Protozoa 30000 3 X 104
25. PGPR
The plant roots associated beneficial soil bacteria that enhance plant growth
Functions
1. Promote plant growth.
2. Enhance the nutrient uptake
3. Biological N2 fixation,
4. Increasing the availability of nutrients in the Rhizosphere
5. Increases in root surface area,
6. enhancing other beneficial symbioses of the host,
Mode of action (PGPR)
1.Direct affect : Plant growth, seed emergence, or improve crop yields and
biocontrol. Phytohormone, production of siderophores .
2. Indirect affect : Antibiotic production, parasitism, competition for nutrients
synthesis of extracellular enzymes to hydrolyze the fungal
cell wall and decreasing pollutant toxicity .
•PGPR can be categorized into three general forms such as
1. Biofertilizer 2. Phytostimulator 3. Biopesticide
27. SOIL HEALTH
• Capacity of a soil to function within
ecosystem boundaries to
biological productivity,
sustain
maintain
environmental quality and promote
plant and animal health.
• In the context of agriculture, it may
refer to its ability to sustain
productivity.
• A healthy soil would ensure proper
retention and release of water and
nutrients, promote and sustain root
growth, maintain soil biotic habitat,
respond to management and resist
degradation
http://www.directs
eed.org/soil_qualit
y.htm
http://www.nrsl.umd.edu/research/NRSLResearchAreaInfo.cfm?ID=14
Poor Good
28. EFFECT ON
SOIL HEALTH
Soil Health is the change
in Soil Quality over time
due to human use and
management or to natural
events.
Descriptive terms for Soil
Health
Organic Matter - high
Crop appearance =
green, healthy,lush
erosion – Soil will not
erode
earthworms – numerous
infiltration – fast, no
ponding
Compaction - minimal
Cornell researcher George Abawi describes soil health
strategies at an Onion Council field day in Wayne County,
N.Y.Photo by Carol R. MacNeil.
In Vernon and surrounding counties are the largest
concentration of organic farmers in Wisconsin.
29. Treatments
pH
OC
(g kg-1)
Available Nutrients (kg ha-1)
SMBC
(mg kg-1)
SMBC % of
soil organic
carbon
N P K
T1 - Control 5.0 4.5 246 7.8 40.8 47.3 1.1
T2 - RDF 5.2 5.2 297 9.5 48.5 75.8 1.5
T3 –biofertilizer - Based package(INM) 5.1 6.0 288 10.9 57.0 136.2 2.3
T4 - 50% RDF(organic)+50 % N FYM 5.2 6.7 359 13.2 57.9 100.5 1.5
T5 – 75%RDF(organic)+25 % N( FYM) 5.1 6.2 316 11.5 50.4 85.8 1.4
T6 – 50 % N (inorganic+50 % N
FYM)+PK (inorganic and adjusted)
5.2 6.3 338 12.0 51.2 90. 2 1.4
T7 -75%N(inorganic+25%N(FYM))+PK
(inorganic and adjusted)
5.1 5.9 317 9.2 49.3 65.0 1.1
SE+ 0.1 0.4 14 2.0 3.4 7.2 0.2
CD at 0.05 % NS 0.9 31 4.3 7.3 15.6 0.4
(Source: Gogai, B., N.G. Barua and T.C. Buruah ,
2010. J. Indian, Soc. Soil. Sci.58(2): 241-244)
(RDF- Rice-60:20:40 kg N,P2O5,K2O ha-1, Soil Type -
Texture Sandy Clay Loam Initial value : pH-5.0, OC-
0.6%,Avail.NP&K-270, 12.21& 116.7 kg ha-1,
microbial biomass carbon-45.2 mg kg-1
Table :1 Effect of nutrient management on microbial biomass carbon and soil
properties after harvest of rice
30. Table NO 2. Recovery of PGPR from the rhizosphere and internal root and stem
tissues of spruce five months after seedlings were inoculated
Inoculum Rhizosphere (log cfu g -1
root)
Internal tissue (log cfu g-1tissue)
Root Stem
L6-16R 5.6 ±0.3 0 0
Pw-2R 5.8 ± 0.5 4.4 ± 2.2 5.0 ± 0.2
S20-R 5.6 ±0.4 0 0
Sm3-RN 7.6 ± 0.1 3.9 ± 1.9 4.6 ± 0.3
Ss2-RN 7.5 ±0.1 0 0
Sw5-RN 7.1 ± 0.2 0 0
6 Antibiotic bacterial strain belong to genera Bacillus and Pseudomonas
were used for innoculation.
2 Strain Bacillus Pw-2R and Pseudomonas Sm3-RN recover internal tissue
Source : Chanway et al (2000) Journal Forest Ecology and Management 57 (5) : 81- 88
31. Table 3. Significance of the main treatment effects and their interactions
based on factorialANOV
A
F-values
AM treatment Bacterial treatment Mycorrhiza∗ bacteria
Shoot growth 141.8∗∗∗ 2.8 NS 1.9 NS
Number of nodules 70.1∗∗∗ 2.7 NS 5.0∗∗∗
AM colonization 340.7∗∗∗ 1.3 NS 1.6 NS
Root length 14.8∗∗∗ 1.0 NS 6.4∗∗∗
Root surface 4.0∗ 1.7 NS 4.4∗∗
Root dry weight 54.8∗∗∗ 0.4 NS 0.4 NS
Thymidine
incorporation
3.3 NS 15.1∗∗∗ 17.1∗∗∗
Leucine
incorporation
18.7∗∗∗ 13.4∗∗∗ 38.8∗∗∗
Ergosterol 19.9∗∗∗ 10.1∗∗∗ 6.7∗∗∗
Chitin 6.8∗∗ 4.9∗ 9.1∗∗∗
Source : Medina et al (2003) j. Applied Soil Ecology
22 (2): 15–28.
32. Table 4 Nutrient (N or P) use-efficiency (mg biomass/mg N or P recovered) of non-mycorrhizal P
fertilized (PO4
3−) or mycorrhizal plants with Glomus mosseae, G. intraradices or G. deserticola either
non-inoculated or inoculated with bacteria [Bacillus pumillus (BP) or Bacillus licheniformis (BL)]
N use-efficiency P use-efficiency
-- BP BL -- BP BL
PO4
3− 181 ± 6.7 - - 804 ± 8.0 - -
Control 271 ± 4.9 428 ± 14.8 485 ± 27.8 1083 ± 4.3 200 ± 25.2 2100± 50.0
G. mosseae 500 ± 28.9 259 ± 3.8 342 ± 5.7 1191± 58.4 1200± 57.7 1271± 73.1
G. intraradices 239 ± 5.5 208 ± 9.9 244 ± 4.5 1069± 91.4 1141± 17.3 1000± 62.9
G. deserticola 321 ± 5.9 256 ± 3.1 309 ± 8.6 1091± 67.7 1107± 42.9 1058± 103.2
Source: Medina et al (2003) j. Applied Soil Ecology . 22 (2): 15-18.
33. Table 5 Shoot N/P ratio of non-mycorrhizal (control or P fertilized PO43−)or
mycorrhizal plants with Glomus mosseae, G. intraradices and G. deserticola either non-
inoculated or inoculated with bacteria (Bacillus pumillus (BP) or Bacillus licheniformis
(BL)
BP BL
Control 4.0 ± 0.5 4.3 ± 0.2 4.2 ± 0.2
(PO4) 3− 4.4 ± 0.2 -- --
Glomus mosseae 2.2 ± 0.3 4.6 ± 0.3 3.7 ± 0.1
G. intraradices 4.5 ± 0.3 5.5 ± 0.2 4.1 ± 0.3
G. deserticola 3.4 ± 0.2 4.3 ± 0.1 3.4 ± 0.2
Medina et al (2003) j. Applied Soil Ecology . 22 (2): 15-18
BP>NP ratio
34. Table :6 .Microbial biomass carbon in maize and rice-based cropping system.
Cropping system Microbial biomass carbon (µg/g)
Control Crop residue + Biofert. +
FYM @ 5 Tonns/ha
Inorganic fertilizer
N, P, K, S, Zn &B
Maize-Wheat 247 298 291
Maize-Wheat-Greengram 327 350 338
Maize-Wheat-Maize-Chickpea 310 338 334
Pigeonpea-Wheat 295 305 301
Rice-Wheat 262 305 300
Rice-Wheat-Greengram 367 376 361
Rice-Chickpea-Rice-Wheat 305 342 358
Rice-Chickpea 301 336 338
Source: Masood Ali and M.S.Venkatesh, (2009). Indian farming , 28 (5) :18-22
37. Table 9 Effects of biological control agents on wheat growth and
yield in salinated soil
Treatments Grain yield
(g/plant)
% Biological yield
(g/plant)
%
Control 19.8 100 62.2 100
TSAU20 24.0* 121 (21%) 78.7* 126
TSAU1 22.4* 113 80.1* 128 (28%)
Adesemoye and Egamberdieva (2013) J. Bacteria in Agribiology :Crop Productivity. 24
(6) :12-25.
TSAU20- Pseudomonas exterimoriantalis
TSAU1 – P
. putida
38. Table 10 Soil aggregation Soybean was grown in either P-fertilized (+P) or not
fertilized (-P) soil, or inoculated (in -P soil) with one of the arbuscular
mycorrhizal (AM) fungi Glomus etunicatum (Ge), Glomus mosseae (Gm), or
Gigaspora rosea (Gr).
Treatment Aggregation
MWD(dry
aggrigation)
WSA(2 to 4 mm) WSA(1 to 2
mm)
WSA(0.25 to
1 mm)
+P 2.32 51.9 69.8 87.9
-P 1.87 55.4 75.7 86.9
Ge 1.92 76.1 81.1 86.3
Gm 1.90 89.7 81.7 87.1
Gr 1.89 78.8 81.9 87.1
MWD- Mean Weight diameter, WSA –Water stable |Aggrigate
Source: Schreiner et al (1997) J. Plant and Soil. 188 (5): 199-209.
39. Table 11. Effect of salinity on root colonization, growth, leaf area, fruit weight,
fruit yield and chlorophyll content of nonmycorrhizal (NM) and mycorrhizal (M)
tomato plants.
Treatments
NaCl (mM)
AMF AMF
colonization
(%)
Root
DW
(g
plant−1
)
Stem
DW
(g
plant−
1)
Leaf
DW
(g
plant−
1)
Leaf
area
(cm2
plant−1
)
Fruit
weigh
t (g)
Fruit
yield
(kg
plant−1)
Chlorop
hyll
content
(mg g−1
FW)
0 NM 0 1.38 8.04 2.70 212 27 4.86 1.22
M 55 3.88 14.22 6.78 256 29 6.92 1.50
50 NM 0 0.86 6.06 1.99 111 18 3.09 0.99
M 39 1.86 13.80 5.91 181 22 4.12 1.44
100 NM 0 0.32 3.37 1.29 58 11 1.15 0.46
M 27 0.66 5.64 1.78 90 16 2.38 1.01
Source: Latefa and Chaoxingb (2010) J.Scientia Horticulturae. 26 (6): 55-59
40. Table 12: Effect of seed inoculation with bio-fertilizers on seed yield of Safflower under
rainfed conditions (Pooled mean over two years, 1999-2000, 2000-2001)
`` 1
Treatment Seed Yield (Kg/ha.)
1999 -2000 2000- 2001 Pooled
Control
(No Nitrogen)
529 551 540
50% N 641 630 635
100% N 742 790 766
Azotobacter seed inoculation 553 597 575
Azospirillum SI 623 650 637
Azotobacter + Azospirillum
SI
645 638 642
50% N + Azotobacter SI 626 654 640
50% N + Azospirillum SI 767 815 790
50% N + Azotobacter +
Azospirillum SI
784 877 829
Sudhakar and Rani (2001) 7th International Saffalower conference. 33 (9): 88-92.
41. Table 13. Effect of microorganisms on mineral content of leaves of tomato
plants grown for 6 months in organic medium (fall crop)
Treatments N (%) P (%) K (%) Ca (%) Mg (%)
Control 3.32a 0.55 7.44 3.05 0.40
Penicillium brevicompactum 3.53 0.73 8.13 2.59 0.34
Penicillium solitum strain 13.58 0.75 7.93 2.45 0.36
Trichoderma atroviride 3.53 0.73 8.11 2.32 0.33
Pseudomonas fluorescens 3.65 0.67 8.07 2.92 0.37
Pseudomonas fluorescens G
strain 2
3.65 0.67 7.99 3.06 0.33
Pseudomonas marginalis 2.81 0.81 7.92 2.63 0.36
Pseudomonas putida B strain 1 3.51 0.66 7.57 3.05 0.37
Pseudomonas syringae strain 1 3.57 0.73 7.99 2.50 0.34
Gravel et al. (2007) J. Soil Biology & Biochemistry. 84 (6): 99-105.
3- Fungi and 5 Bacterial spp.
42. Table14 Effect of Azospirillium brasilense inoculation on grain yield of maize
in different regions of Mexico, under different levels of applied N
Region
(location)
N rate
(kg ha-1)
Grain yield
(kg ha-1)
Difference
(%)
Non-inoculated Inoculated
Oaxaca 0 2854 3419 +21
Campeche a 18 1400 2100 +50
Quintana Roo 0 1502 1900 +27
Domego 30 1234 2204 +78
Hidalgo 46 1050 2080 +95
Campeche b 110 4590 5100 +10
Pubela 140 3298 3212 -3
Kennedy et al (2006) J. Soil Biology & Biochemistry. 22 (4) : 66-72
Azospirilium brasilense is used innoculated biofertilizer for maize, also diazototrophic
bacteria.
44. Table 16. Yield components and grain yield of rice (cultivars Oking seroni
and IR72) as influenced by rhizobial inoculation and N rate
Treatment Panicles per pot Spikelets per panicle Grain yield g pot-1
0 kg N ha-1 90 kg N 0 kg N ha-1
ha-1
90 kg
ha-1
N 0 kg N ha-1 90 kg N
ha-1
IR72
Control 6.6 8.4 93 125 11.9 18.2
E12 7.3 9.6 97 140 12.9 22.4
IRBG74 7.5 9.9 112 148 14.5 23.4
Control 5.9† 9.3
Oking
104
seroni
105 12.7 20.7
E12 7.5 9.8 108 140 15.2 24.3
IRBG74 7.1 8.0 105 136 14.2 20.9
E12-Rhizobium liguminosarum bv.trifoli and Rhizobium IRBG74 were grown in Yeast Manitol
broth. Mechanism that improve single leaf net phytosyntetic rate
Source: Peng et al. (2002) AGRONOMY JOURNAL33 (6) :85-92.
45. Table 17. Effect of inoculation with selected plant growth-
promoting rhizobacteria (PGPR) on growth and yield of two
wheat cv. PGPR Isolaters grown in pots.
PGPR
Isolaters
No. of tillers
per plant
Straw yield
(gram per plant)
Grain yield
(gram per plant)
Pasban-90 Inqlab-
91
Pasban-
90
Inqlab-
91
Pasban-90 Inqlab-
91*
Uninoculated 4.31 (100%) 4.43 NS 5.73 5.82 3.07 3.03 NS
Ha21 4.30 4.50 5.34 6.24 3.14 3.13
Ha22 5.0 4.10 6.09 5.79 3.15 2.96
Ha23 4.90 4.40 6.01 6.18 3.49 (13.9) 3.24
Ha30 5.31
(23.2%)
4.70 6.44 6.41 3.52
(14.9%)
3.06
Khalid et al.(2004) Journal of Applied Microbiology. 33 (6): 78-85.
Seed innoculated with 4 PGPR isolate strainAuxin
46. Table 18. Effect of molasses spray applied to soil on
increase number of microorganism.
Sr.No Microbial Group Dilution Number of microorganism*
Control Molasses (0.1%)
1 Fusarium 102 102 413
2 Fungi 103 44.4 102
3 Bacteria 106 252 407
4 Actinomycetes 106 2.51 3.51
•Number / gm soil (dry weight basis).
•Molasses 0.1 % is applied in to soil in aqueous solution
Higa and Wididana(2000) Ammerican Society of Agronomy. 26 (8): 78-85
47. Table 19. Effect of foliar applied molasses spray on
number of microorganism on leaf surface of turnip
Sr.No Microbial Group Dilution Number of microorganism*
Control Molasses (0.1%)
1 Fusarium 102 8.42 14.0
2 Fungi 102 12.4 63.3
3 Bacteria 104 3.89 8.90
4 Actinomycetes 104 2.46 9.21
5 N Fixing Bacteria 103 1.42 10.3
* Number / gm soil (dry weight basis). Microorganism were counted on leaf surface
of turnip. Molasses 0.1 % is applied.
Higa and Wididana(2000) Ammerican Society of Agronomy. 26 (8): 78-85
48. 1. Soil microbial communities play an important roll in
maintaining soil and plant health as well as agricultural
production.
2. Soil microbes improve physical chemical and biological
properties of soil .
3. Various interacting microbes produces phytoharmones, which
have been inhabits or promote roots growth , protect plant
against biotic and abiotic stress and improve nutrient
acquisition by roots.
4. Soil microorganisms appear to be very suitable and predictive
tools in soil health monitoring.
5. PGPR can be very effective and are potential microbes for
improving soil fertility and enhancing the agriculture yield.
6. Microorganism helps to solublization and mobilization of
essential nutrient.
Conclusion
49. Department of Soil Sciencce andAgricultural Chemistry,
V.N.M.K.V., Parbhani.
Thank you for your
attention
