Abstract
Soil amendments in viticulture enhance both grapevine growth and soil chemistry. However, their role in soil microbial diversity and disease suppression in the vineyard has not yet been thoroughly explored. The purpose of this thesis was to explore the influences of mulches and composts on vineyard rhizosphere microbial populations and diversity, specifically the effects on the microbial populations living in the grapevine rhizosphere. One NSW site in Wagga Wagga and two South Australian vineyard trial sites, one in the Clare Valley and one at Langhorne Creek, were assessed. The application of commercially prepared Grape Marc (GM) compost at Langhorne Creek significantly increased bacterial and fungal rhizosphere populations. This result prompted the initiation of a vineyard trial at Wagga Wagga, in which two types of GM based composts (pine bark based and pine sawdust based) were designed, produced and applied for the investigation of shorter term effects on grapevine rhizosphere microbial population and diversity. The application of GM compost in viticulture has great potential to improve vineyard soil health and contribute to grapevine disease suppression but its use must be economically viable. Grape marc (GM) is a waste by-product produced in the wine making process, so it is a relatively inexpensive potential component of composts for vineyard soil. As pinebark, a widely used compost component, is expensive, whereas sawdust is a relatively inexpensive industry waste product, there was a need to investigate differences in the effects on the rhizosphere microbial community of GM compost produced with these two different types of carbon source. To gain a clear insight into the effects of soil amendments on the vineyard rhizosphere microbial communities, three different methods were used to analyse microbial populations and diversity. Plate culturing (Chapter 3), using seven different agar types, successfully evaluated population changes of microbial groups. To investigate differences in functional diversity, the Community Level Physiological Profile (CLLP) method using Biolog Ecoplates™ (Chapter 4) was utilised. Possible changes in genetic diversity were then explored using the Terminal Restriction Fragment Length Polymorphism (TRFLP) technique (Chapter 5). Finally, to investigate the potential for disease control, 28 isolates of Gram negative fluorescent bacteria were isolated from the GM composts and screened for antagonistic and defence enzyme activity in Chardonnay cuttings co-inoculated with the fungal pathogen, Rhizoctonia solani (Chapter 6). In general, the mulch and compost soil amendments influenced bacterial and fungal grapevine rhizosphere populations differently. Plate culturing showed that organic amendments such as mulches and composts increased the rhizosphere bacterial and fungal populations at all three sites investigated. The application of glyphosate decreased bacterial and fungal populations. Some differences in population and diversity responses were noted for the pinebark and sawdust based GM composts. The application of pinebark GM compost increased the bacterial populations whereas the sawdust based GM compost produced higher populations of fungi. Furthermore, both the TRFLP and the Biolog Ecoplates™ methods showed that the pine bark GM compost increased rhizosphere functional and genetic diversity than the sawdust GM compost. Understanding the effects of GM composts on grapevine disease suppression is of great relevance for successful vineyard management. After the addition of the GM composts at the Wagga Wagga site, the largest bacterial population increases were colonies growing on Pseudomonads agar. Results from the final experimental chapter in this thesis showed that two of these Gram negative bacterial had antagonistic traits towards the fungal pathogen Rhizoctonia solani, thus indicating the potential of GM compost in vineyard floor management to increase suppressive bacterial populations and potentially contribute to grapevine disease management.
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Claims 12
Claim · model-written summary
Grape marc compost significantly increased bacterial and fungal rhizosphere populations at Langhorne Creek.
- Treatment
- Grape Marc (GM) composte0
- Outcome
- bacterial and fungal rhizosphere populationse0
- Direction
- increasede0
- Setting
- Langhorne Creeke0
VitisNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The application of commercially prepared Grape Marc (GM) compost at Langhorne Creek significantly increased bacterial and fungal rhizosphere populations”
t0“grapevine”
Claim · model-written summary
Plate culturing successfully evaluated changes in microbial group populations.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Plate culturing (Chapter 3), using seven different agar types, successfully evaluated population changes of microbial groups”
t0“grapevine”
Claim · model-written summary
Mulch and compost amendments affected bacterial and fungal grapevine rhizosphere populations differently.
- Treatment
- mulch and compost soil amendmentse0
- Outcome
- bacterial and fungal grapevine rhizosphere populationse0
- Direction
- differentlye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the mulch and compost soil amendments influenced bacterial and fungal grapevine rhizosphere populations differently”
Claim · model-written summary
Organic mulches and composts increased rhizosphere bacterial and fungal populations at all three sites.
- Treatment
- organic amendments such as mulches and compostse0
- Outcome
- rhizosphere bacterial and fungal populationse0
- Direction
- increasede0
- Qualifier
- all three sites investigatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“organic amendments such as mulches and composts increased the rhizosphere bacterial and fungal populations at all three sites investigated”
t0“grapevine”
Claim · model-written summary
Glyphosate application decreased grapevine rhizosphere bacterial and fungal populations.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The application of glyphosate decreased bacterial and fungal populations”
t0“grapevine”
Claim · model-written summary
Pinebark grape marc compost increased bacterial populations.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The application of pinebark GM compost increased the bacterial populations”
t0“grapevine”
Claim · model-written summary
Sawdust-based grape marc compost produced higher fungal populations.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the sawdust based GM compost produced higher populations of fungi”
t0“grapevine”
Claim · model-written summary
Pine bark grape marc compost increased rhizosphere functional diversity compared with sawdust grape marc compost.
- Treatment
- pine bark GM composte0
- Outcome
- rhizosphere functionale0
- Direction
- increasede0
- Comparator
- sawdust GM composte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“pine bark GM compost increased rhizosphere functional and genetic diversity than the sawdust GM compost”
t0“grapevine”
Claim · model-written summary
Pine bark grape marc compost increased rhizosphere genetic diversity compared with sawdust grape marc compost.
- Treatment
- pine bark GM composte0
- Outcome
- genetic diversitye0
- Direction
- increasede0
- Comparator
- sawdust GM composte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“pine bark GM compost increased rhizosphere functional and genetic diversity than the sawdust GM compost”
t0“grapevine”
Claim · model-written summary
Following grape marc compost addition at Wagga Wagga, the largest bacterial population increases were on Pseudomonads agar.
- Treatment
- GM compostse0
- Outcome
- bacterial population increasese0
- Direction
- largeste0
- Setting
- Wagga Wagga sitee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“After the addition of the GM composts at the Wagga Wagga site, the largest bacterial population increases were colonies growing on Pseudomonads agar”
t0“grapevine”
Claim · model-written summary
Two isolated Gram negative bacteria showed antagonistic traits toward Rhizoctonia solani.
- Interactor
- Rhizoctonia solani
Rhizoctonia solanie0pathogen - Second interactor
- Gram negative bacteriale0biocontrol_agent
- Outcome
- antagonistic traitse0
- Value
- twoe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“two of these Gram negative bacterial had antagonistic traits towards the fungal pathogen Rhizoctonia solani”
t0“grapevine”
Claim · model-written summary
The authors propose grape marc compost as a potential tool to increase suppressive bacteria and aid grapevine disease management.
- Outcome
- increase suppressive bacterial populations and potentially contribute to grapevine disease managemente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“potential of GM compost in vineyard floor management to increase suppressive bacterial populations and potentially contribute to grapevine disease management”
t0“grapevine”
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See all 5 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.