Rhizosphere vs phyllosphere

Agricultural Microbiology

1. Rhizosphere and Phyllosphere
Dr. S. PARTHASARATHY, M.Sc. (Agri)., Ph.D.
Assistant Professor (Plant Pathology)

5. Rhizobium, Azotobacter, Clostridium
Beijerinckia, Pseudomonas, Alternaria

6. Therhizosphereisthenarrowregionofsoilthatisdirectly
influencedbyrootsecretions,andassociatedsoilmicroorganisms
knownastherootmicrobiome.

7. ThetermRhizospherewasintroducedbytheGermanscientistHiltnerin
1904.
Thetermrhizosphereisoftendividedintotwogeneralareas,
•theinnerrhizosphere(veryrootsurface)and
•theouterrhizosphere(immediateadjacentsoil).Themicrobial
numbersarelargerintheinnerzone.
Theendorhizosphereincludesportionsofthecortexandendodermisin
whichmicrobesandcationscanoccupythe"freespace"betweencells
(apoplasticspace).
Therhizoplaneisthemedialzonedirectlyadjacenttotherootincluding
therootepidermisandmucilage.
Theoutermostzoneistheectorhizospherewhichextendsfromthe
rhizoplaneoutintothebulksoil.

9. Rhizosphereeffect
Itindicatestheoverallinfluenceofplantrootsonsoilmicroorganisms.It
canbeputonaquantitativebasisbytheuseofRoot-Soilrelationship.
Microbialinteractioninrhizosphere
•Plantexudatesarethemainfactorswhichinfluencethegrowthof
rhizospherecolonizers.
•Microorganismspresentintherhizosphereplayimportantrolesin
ecologicalfitnessoftheirplanthost

10. Functions
1. Decomposition of plant residue and organic matter
•Humus formation, mineralization of organic nitrogen, sulphur, and phosphorous
2. Increasing nutrient availability of phosphorous, magnesium, iron, zinc &
copper.
•Symbiotic mycorrhizalassociation, Production of organic chelating agents
•Oxidation-reduction reaction, Phosphorous solubilisation
3. Improve biological nitrogen fixation
•Free living bacteria and cyanobacteria
•Associative microorganisms
•Symbiotic legume and non-legume
4. Promoting plant growth
•Production of plant growth hormones, enhanced nutrient use efficacy
•Protection against root pathogens and pseudopathogens
5. Controlling deleterious microorganism
•Plant disease, nematodes and insects
6. Biodegrading synthetic pesticides and contaminants
7. Enhancing drought tolerance of plants
8. Improving soil aggregation

11. Functions

12. Theterm“phyllosphere”wasfirstpublishedbyDr.JakobaRuinenin1961,.She
calledtheinterfacebetweenleavesandairis“phyllosphere”,andsaidthatthis
wasamuchneglectedmilieu,comparedtostudiesoftherhizosphere.
Subdivisionsofphyllosphere
•Theyarecaulosphere(stems),
phylloplane(leaves),anthosphere
(flowers),andcarposphere(fruits).
•Phyllosphereismainlyinhabitedby
bacteria,yeast,andfungi.
•Bacteriaarefoundinnumbers
averaging10
6
to10
7
cells/cm
2
(upto
10
8
cells/g)ofleaf.
•Somephylloplanemicrobesareable
tofixnitrogen(N)fromatmospheric

13. Functions
1. Nutrient management
•Leaf nodulation -N fixation
•Cytokininproduction
2. Disease management
•Protection against pathogens
•Induced systemic resistance
3. Environmental stress tolerance
•Control of ice nucleation-active bacteria.
•Protection through aggregation.

15. Thank
You