Plant Growth Promoting Rhizobacteria's, PGPR

Discussion in 'Organic Lawn Care' started by ICT Bill, Apr 4, 2008.

  1. ICT Bill

    ICT Bill LawnSite Platinum Member
    Posts: 4,115

    I have had some intense conversations with some folks via email and on the phone about the make up of certain soil biology and what do they do exactly to "Promote Growth".
    In many instances these strains of soil biology are disease suppresive either through competition or out right nuking (enzymes) of the pathogen. I have pared down an article that discusses this for Trichoderma. It gets a little technical but shows the interact and why it works.

    Plant Biocontrol by Trichoderma spp.
    Ilan Chet, Ada Viterbo and Yariv Brotman
    Biological control, the use of specific microorganisms that interfere with plant pathogens and pests, is a nature-friendly, ecological approach to overcome the problems caused by standard chemical methods of plant protection. Our main research interest focuses on a novel approach for induction of local and induced systemic resistance (ISR) towards plant pathogens, using a "mycorrhiza-like" saprophytic fungus, usually used as a biocontrol agent.

    Trichoderma spp. are fungi that are present in nearly all agricultural soils and in other environments such as decaying wood. The antifungal abilities of these beneficial microbes have been known since the 1930s, and there have been extensive efforts to use them for plant disease control since then.

    These fungi grow tropically toward hyphae of other fungi, coil about them in a lectin-mediated reaction, and degrade cell walls of the target fungi by the secretion of different lytic enzymes. This process (mycoparasitism) limits growth and activity of plant pathogenic fungi.

    Specific strains of fungi in the genus Trichoderma colonize and penetrate plant root tissues and initiate a series of morphological and biochemical changes in the plant, considered to be part of the plant defense response, which in the end leads to induced systemic resistance (ISR) in the entire plant. The capability of T. harzianum to promote increased growth response was verified both in greenhouse experiments and in the hydroponic system. A 30% increase in seedling emergence was observed and these plants exhibited a 95% increase in root area. Similarly an increase in P and Fe concentration was observed in Trichoderma inoculated plants.

    The terminology associated with biocontrol in the rhizosphere and with soil–plant–microbe interactions has gradually become more complex through the use of a range of descriptive rather than mechanistic terms such as plant growth promotion and rhizosphere competence. Much like the situation with PGPR, many saprotrophic fungi, particularly certain isolates of Trichoderma species, can provide plant growth promotion in the absence of any major pathogens. In many cases these studies are restricted to simple observations of improved plant growth with no indication of the possible mechanisms involved, although there are exceptions. For example, Trichoderma harzianum 1295–27 was shown to solubilize phosphate and micronutrients that could be made available to provide plant growth

    So they nuke the bad guys and feed the plant too, pretty cool.

    I have endless reams of this type of thing on specific soil biology, BORING
     
  2. treegal1

    treegal1 LawnSite Gold Member
    Posts: 3,911

    one picture is a thousand words
    the larger is pythium the holes and small dots are tricoderma

    trichoderma2b.jpg
     
  3. phasthound

    phasthound LawnSite Platinum Member
    Posts: 4,575

    Great stuff! Keep it coming.
     
  4. Organic a go go

    Organic a go go LawnSite Member
    Posts: 211

    Not boring . Post away.
     
  5. ICT Bill

    ICT Bill LawnSite Platinum Member
    Posts: 4,115

    6 or 7 paragraphs to say

    A 30% increase in seedling emergence was observed and these plants exhibited a 95% increase in root area. Similarly an increase in P and Fe concentration was observed in Trichoderma inoculated plants.
     
  6. treegal1

    treegal1 LawnSite Gold Member
    Posts: 3,911

    BILL, your the best, boring is what the trichoderma do best, they drill a hole in the offender and move in
     
  7. DUSTYCEDAR

    DUSTYCEDAR LawnSite Fanatic
    from PA
    Posts: 5,137

    neat stuff
     
  8. Barefoot James

    Barefoot James LawnSite Senior Member
    Posts: 984

  9. ICT Bill

    ICT Bill LawnSite Platinum Member
    Posts: 4,115

    our tea currently has

    Trichoderma harzianum
    T.viride
    Giocladium virens
    T.koningii
    T.polysporum
    in the mix

    they are also in the 1-2-3 hydroseed

    It is important to be specific about the strain T.koningii and T.polysporum are almost mycorrhizae look alikes with their interaction with the root and do not have anti fungal capabilities, Trichoderma harzianum does have fungicide capabilities there are also many strains within this strain
     
  10. Smallaxe

    Smallaxe LawnSite Fanatic
    Posts: 10,080

    These types of articles always raise more questions than they answer...

    1 question is: Are they able to grow above/on the surface of the soil, if there is a pathogen there?
     

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