effects of mixed species cover crop on tomato biomass and plant disease suppression
TRANSCRIPT
Effects of mixed species cover
crop on tomato biomass and
plant disease suppression
Presenter: Emily Nguyen1
Brian B. McSpadden Gardener2 and Sun-Jeong Park2
Department of Biological Science, California State University
of Fullerton, Fullerton CA
Department of Plant Pathology, OARDC, The Ohio State
University, 1680 Madison Ave, Wooster OH
1
Introduction
• To get certified as organic farming, farmers can not
apply chemicals up to 3 years.
• Cover crops rotation can increase microbial diversity &
organic matter (Schonbeck and Morse, 2006).
• Benitez el al. (2009)
oMixed hay soil increase tomato biomass & disease
suppression.
oMitsuaria & Burkholderia, 2 novel biocontrol
bacteria were isolated from mixed hay soils.
2
Intro (cont.)
Cover
Crop
Planting
time
Mature
time
Benefits
Radish Early
Spring
Late
summer
NR= take up and holds soluble soil
nitrogen
B= harbors beneficial insects
TS= conditions, mellow top soil
Winter
Rye
Fall May NR= takes up and holds soluble soil
nitrogen
K= makes soil potassium more available
Hairy
Vetch
Early fall May N= fixed nitrogen
B= harbor beneficial insects
P= make soil phosphorous more available
3
Schonbeck and Morse (2006)
Table 1: Benefits of some cover crops to soil. Letters in bold indicate a strong effect.
4
Winter Rye Hairy Vetch
Intro. (cont.)
Winter rye and hairy vetch cover crops were photographed in May, 2011.
Objectives and hypothesisObjectives:
1) To compare effects of mixed vs. single species
cover crops on tomato biomass &
2) Compare effects of mixed vs. single species on
plant disease suppression
3) To isolate bacteria associated with plant disease
suppression & mixed species cover crops.
Hypothesis:
Mixed cover crops contribute to higher tomato
biomass and less disease symptom than single
cover crops. 5
Methods
6
Experimental DesignRandomized Complete Block
Mixed Hay, Rye+Vetch
Radish, Rye, & Vetch
East Badger, Fry (compost),
& Fry A
1) Soil fertility test
% organic matter & P
2) Fresh shoot biomass
above ground shoot
weight
3) Bacteria collection
~ 8000 bacteria isolates from
rhizosphere (1/2 R2A, ½ R2A+ Root
extract, 1/3 King’s Medium B, &
Leptothrix strain
Whole cell PCR
Pathogen
inoculation
108 Xanthomonas
cells/ml on 1
leaflet
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Fig. 1: % Organic Matter
Results_ Soil fertility
No significant difference of cover crops on % organic matter
8
Fig. 2: Extractable Phosphate analysis from soil
Results_ Soil fertility
No significant difference of cover crops on P
Results_ fresh shoot weight
Fig. 3: Fresh shoot tomato biomass in July, 2011.
Field
Cover Crop
FryAF
ry
East
Bad
ger
Vet
ch
Rye
Vet
chRye
Rad
ish
Mix
ed hay
Vet
ch
Rye
Vetc
hRye
Rad
ish
Mix
ed h
ay
Vet
ch
Rye
Vet
chRye
Radi
sh
Mix
ed h
ay
1800
1600
1400
1200
1000
800
600
400
200
Fre
sh
sh
oo
t b
iom
ass,
g
9Plants from mixed hay soil have more fresh shoot weight
Results_ % disease symptoms
10
Fig. 4: Ranking score of percentage disease symptoms
Less disease symptom plants from rye + vetch soil,
significantly 1/3 fields
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NC
WC PC
DNA PCDNA PC
WC PC
Mitsuaria_H24L5 Burkholderia_R2F4
Samples spiked with 6ul
of R2F4 DNA
100bp L
~450 bp
500400
Fig. 5: Optimization of Mitsuaria and Burkholderia screening PCR.
Results_ Double freeze/thaw whole cell PCR
Burkholderia side, bands matched with positive control band
Successful double freeze/thaw screening method
Conclusion
• Tomato plants from mixed species of hay tended to have more fresh shoot biomass.
• Tomato plants from rye + vetch tended to show less disease symptom, significantly in 1/3fields.
• Double freeze-thaw has been successfully optimized to screen for Mitsuaria and Burkholderia PCR.
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Future Study
Screen and identify potential bacteria isolates
using a sequence marker following the method
of Benitez et al. (2009).
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Literature Cited
1) Baysal, F., M. S. Benitez, M. D. Kleinhenz, S. A. Miller, and B. B. McSpadden Gardener.
2008. Field management effects of damping-off and early season vigor of crops in a
transitional organic cropping system. Phytopathology 98:562-570.
2) Benitez, M. S., and B. B. McSpadden Gardener. 2009. Linking Sequences to Function in
Soil Bacteria: Sequence-Directed Isolation of Novel Bacteria Contributing to Soilborne Plant
Disease Suppresion. Appl. Environ. Microbiol. 75:915-924.
3) Pal, K. K., and B. B. McSpadden Gardener. 2006. Biological Control of Plant Pathogen.
The Plant Health Instructor DOI: 10.1094/PHI-A-2006-1117-02.
4) Schonbeck, M., and Morse, R. 2006. Cover Crops for all Seasons: Expanding the cover
crop tool box for organic vegetable producers. Virginia Association for Biological Farming
Information Sheet.
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Acknowledgements
• Funding to support the development of these materials
was provided by the USDA’s Organic Agriculture
Research and Extension Initiative Grant 2009-51300-
05512.
• Many thanks to Summer Research Opportunity Program
at the Ohio State University
• Special thanks to Chunxue Cao, Xiaoqing Rong,
Veronica Cepeda and Matthew Worth for assisting with
field works.
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McSpadden Gardener’s Lab Members
Summer 2011
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Thank You!