Sustainable Agriculture. Management and Utilization of Arbuscular Mycorrhizal Fungi. Take advantage of mycorrhizal fungi for improved soil fertility and plant health.

1. Mycorrhizal Fungi for Improved Soil
Fertility and Plant Health
(or “Management and Utilization of
Arbuscular Mycorrhizal Fungi”)
David Douds
USDA-ARS Eastern Regional Research Center
david.douds@ars.usda.gov

2. Introduction


Structure
Function
Management of AM fungi
On-farm production and utilization of
inoculum
Field trials

3. Arbuscular Mycorrhizal [AM] fungi

Arbuscule
(L. “small tree”)

Mycorrhiza
(Gr. “fungus root”)

6. - exudate
+ exudate

8. Development of an arbuscule
Kinden and Brown, 1979

11. Function of mycorrhizas

13. Green ash (Fraxinus pennsylvanica)

18. Other benefits
To the plant:


Enhanced water relations
Enhanced pest resistance
To the soil:

Stability of soil aggregates (glomalin)

19. How does the AM fungus benefit?
AM fungi are “obligate symbionts”
They must live in symbiosis with plants to
complete their life cycles
 Why?




Metabolic division of labor among the
structures of the fungus
Only the fungus within the root can absorb
sugars for energy and make lipids necessary
for storage and growth
Germinating spores can only grow as long as
their stored lipids hold out

20. How can we take advantage of the
AM symbiosis in agriculture?
1. Manage the AM fungi indigenous to the
soil (row crop farms)
2. Inoculate with effective isolates
(horticulture crops, vegetable farms, labor
intensive farms)

21. I. Farm management practices that
influence indigenous AM fungi
Fertilization
 Pesticide application
 Over wintering cover crops
 Crop rotation
 Tillage
 Farming System

Cooperative research with The Rodale Institute

22. 1. Over wintering cover crops

Used for:





Erosion control
Nutrient management
Organic matter
Weed management
Fringe benefit:


Build populations of AM
fungi
Function as a ‘mini’
crop rotation

23. Over wintering crop of hairy vetch increased the
AM fungus inoculum present in the soil

24. Long fallow disorder

25. Similar to bare fallows:


Flooded soil syndrome
Stale weed seed bank treatments

26. 2. Crop rotation




Some AM fungi are more
prolific when grown with a
particular host plant
The AM fungi most
prevalent after growth of
one crop may not be the
ones most beneficial to
that crop
AM fungi may play a role in
yield decline characteristic
of continuous monoculture
Implications for a big
switch to continuous corn
for ethanol production?

27. 3. Tillage

Tillage interferes with
two functions of the
extraradical mycelium
of AM fungi:
1. As infective
propagules

28. 2. As nutrient absorbing organs of the
symbiosis
Fairchild and Miller, 1990
S h o o t d r y w t (g )
No added P
0.9
Undisturbed
Disturbed
0.8
0.7
a. Corn grown for 4 wks
in inoculated soil
0.6
0.5
b. Harvest shoot only
0.4
0.3
1
2
3
Cycle
S h o o t d r y w t (g )
+ 160 µgP g-1 Soil
0.9
0.8
c. Disturb soil in half of
pots, replant
0.7
0.6
d. Repeat cycle
0.5
0.4
1
2
Cycle
3

29. 6. Farming system

The Farming Systems Trial
®

30. Soils from the organic rotations have a
higher AM fungus inoculum potential

31. … and greater spore populations

32. 
Largely due to the
over wintering cover
crops, the organic
farming systems have
live plant cover 70%
of the year vs. 40%
for the conventional
farming system.

33. II. Inoculation with AM fungi
Options:
commercially available inocula
produce it yourself
Target farmers:
vegetable producers who grow their own
seedlings
labor intensive farms

34. On-farm inoculum production
Materials
compost
vermiculite
grow bags
Transplant:
Bahiagrass (Paspalum notatum) seedlings
precolonized by AM fungi
Weed and water for one growing season (remove flowers in
mild climates)
Inoculum is ready for use the following spring
Details in the web article on the handout

35. Considerations

Introduce pathogens?



Introduce weeds?



Compost has pathogen suppressive qualities
Bahiagrass unlikely to share pathogens with
eventual crop host
Bahiagrass is frost killed (temperate climates)
Some weeds are present in the compost
Functional diversity of AM fungi

36. 7 gallon “grow bags”

37. Inoculum of AM fungi

Spores

Infective hyphae

Colonized roots

38. Production of propagules of AM fungi in 1:4 [v/v]
mixtures of yard clippings compost and
vermiculite. Results of MPN bioassays.
Inoculated
AM fungus
Propagules
cm-3
bag (x106)
Glomus
mosseae
Glomus
etunicatum
Glomus
geosporum
Glomus
claroideum
120
2.4
750
15.0
120
2.4
365
7.3

40. Spore production varies with
dilution

41. Modifications to on-farm inoculum
production system

Propagate indigenous isolates of AM fungi



Add field soil to compost+ vermiculite mix
Pre-inoculate bahiagrass with field soil
Use of alternate “inert” diluents


Horticultural potting media
Perlite

42. Modifications to on-farm system
Diluents
Field soil

43. Where to collect the soil- top 2-4 inches
Means of 3 years
100
-3
Conv
P r o p a g u le s c m
80
Legume
Manure
60
40
20
0
0
10
20
30
40
50
60
70
80
Soil Depth
Rodale Farming Systems Trial

44. Utilization of inoculum in the
greenhouse
Goal: produce a
well-colonized
seedling via
organic practices,
of comparable size
to a conv.-grown
seedling.
 Manipulation of
media, N P
availability


45. R o o t le n g th c o lo n iz e d (% )
Response of colonization to P level for
tomato, pepper, and bahiagrass
70
Tomato (Crista)
Pepper (Lafayette)
Bahiagrass
60
50
40
30
20
10
0
0
10
20
30
40
50
P concentration (ppm)
60
70

46. How does this happen?

Roots growing in high P exude less of the
hyphal branching signal


Roots release less sugar to the fungus
already within the root


This leads to less spread of colonization
Less carbohydrate supplied to the fungus


This leads to less new colonization
This leads to decreased spore production
An important factor for the utilization of
AM fungi in the greenhouse

47. Organic media experiment
1. Conventional (Premier pro mix +
Hoag (0.31 ppm P) 3X /wk)
Rodale potting mix (20% compost)
2. No N addition
3. + Blood Meal (add all at once, 9 g/flat)
4. + Fish (added 3X /wk)
Sunshine Mix #1 (SunGro Horticulture)
5. No N addition
6. + Blood Meal (add all at once)
7. + Fish (added 3X /wk)

48. Results with leek cv. Musselburgh
Conv
Rodale
0N
BM
Fish
Sunshine
0N
BM
Fish
Shoot wt (g) Shoot %P Colon %
0.09 c
0.15 c
27.7 ab
0.08 c
0.25 a
0.16 abc
0.35 ab
0.40 ab
0.42 a
27.8 ab
3.2 c
16.6 bc
0.12 bc
0.19 ab
0.19 ab
0.36 ab
0.29 b
0.33 ab
34.2 a
5.7 c
16.2 bc

49. C o lo n iz a tio n (% r o o t le n g t h )
C o lo n iz e d r o o t le n g t h (c m )
Follow-up experiment
30
Blood Meal 3x/wk
Blood Meal To
A
20
10
0
0
1
2
3
4
36
30
B
24
18
12
6
0
0
1
2
3
4
2
3
4
In fe c tio n U n its
35
30
C
25
20
15
10
5
0
0
1
Weeks
Leek cv.
Musselburgh in the
growth chamber
 Single addition of
blood meal did not
inhibit early
colonization, but
inhibited
subsequent spread
of colonization.

Hoag -P

50. Tomato cv. BHN 589
Treatment
Shoot Dry Wt
(g)
Nonmycorrhizal
1. Conv
0.68 ± .04
Colon
(%)
Treatment

Shoot Dry Wt
(g)
Colon
(%)
0
Mycorrhizal
1. Conv
0.62 ± .03
15.0 ± 1.2
Rodale Mix
2. 0 N
3. Blood meal
4. Fish
0.52 ± .03
0.92 ± .06
0.87 ± .09
0
0
0
Rodale Mix
2. 0 N
0.27 ± .02
3. BM
1.00 ± .08
4. Fish
0.76 ± .03
6.7 ± 1.3
3.7 ± 0.8
10.3 ± 2.0
Sunshine Mix
5. 0 N
6. Blood Meal
7. Fish
0.12 ± .01
0.18 ± .05
0.17 ± .02
0
0
0
Sunshine Mix
5. 0 N
0.11 ± .01
6. BM
0.57 ± .03
7. Fish
0.34 ± .05
1.2 ± 0.6
5.3 ± 1.4
8.4 ± 1.4
ANOVA (full model Pr>F)
Myc
0.2404
Tmt
<0.0001
MXT
<0.0001
<0.0001
<0.0001
<0.0001

51. Pepper cv. Revolution

Nonmycorrhizal
1. Conv
Rodale Mix
2. 0 N
3. BM
4. Fish

0.39 ± .02
0.25 ± .02
0.79 ± .05
0.56 ± .04
Sunshine Mix
5. 0 N
0.13 ± .01
6. BM
0.36 ± .04
7. Fish
0.21 ± .02
ANOVA (full model Pr>F)
Myc
Tmt
MXT
<0.0001
<0.0001
<0.0001
<0.0001
0.6185
0.6185
Mycorrhizal
0
1. Conv 0.31 ± .024
2.0 ± 0.5
0
0
0
Rodale Mix
2. 0 N 0.22 ± .01
3. BM 0.57 ± .06
4. Fish 0.34 ± .05
1.8 ± 0.8
1.8 ± 0.6
1.5 ± 0.5
Sunshine Mix
5. 0 N 0.09 ± .01
6. BM 0.42 ± .01
7. Fish 0.19 ± .02
2.2 ± 0.7
2.1 ± 0.3
0.8 ± 0.3
0
0
0

52. Pepper cv. Revolution yield (Rodale)
Nonmycorrhizal
1. Conv
kg/plant
-
Rodale Mix
2. 0 N
3. Blood meal
4. Fish
1.61 ± .10
1.73 ± .12
Sunshine Mix
5. 0 N
6. Blood Meal
7. Fish
1.48 ± .25
1.39 ± .14
1.59 ± .24
1.59 ± .27
ANOVA (full model Pr>F)
Myc
0.7162
Tmt
0.2565
MXT
0.7484
Mycorrhizal
1. Conv
kg/plant
-
Rodale Mix
2. 0 N
3. Blood meal
4. Fish
1.49 ± .18
1.74 ± .16
1.74 ± .14
Sunshine Mix
5. 0 N
6. Blood Meal
7. Fish
1.25 ± .16
1.59 ± .0
1.80 ± .10
*The average yield/plant at local
conv. farm= 1.4 - 1.7 kg/plant

53. Pepper cv. Revolution yield (conv)
Nonmycorrhizal
1. Conv
kg/4plants
7.39 ± 1.07
Rodale Mix
2. 0 N
3. Blood meal
4. Fish
8.04 ± .76
7.21 ± .79
6.65 ± .91
Sunshine Mix
5. 0 N
6. Blood Meal
7. Fish
5.61 ± .96
6.64 ± 1.14
6.93 ± 1.12
ANOVA (full model Pr>F)
Myc
0.0394
Tmt
0.7928
MXT
0.4314
Mycorrhizal
1. Conv
kg/4plants
8.48 ± .79
Rodale Mix
2. 0 N
3. Blood meal
4. Fish
7.00 ± 1.13
7.33 ± .80
8.08 ± .42
Sunshine Mix
5. 0 N
6. Blood Meal
7. Fish
7.77 ± .46
9.43 ± .73
7.54 ± 1.11

54. Tomato cv. BHN (Rodale)
Treatment
Nonmycorrhizal
1. Conv Rodale Mix
2. 0 N
3. Blood meal
4. Fish
Sunshine Mix
5. 0 N
6. Blood Meal
7. Fish
Mkt
Term
(kg/2 pl)
Treatment
Mkt
Term
(kg/2 pl)
Mycorrhizal
1. Conv
-
1.9 ±.2 7.6 ±.3
2.8 ±.5 8.9 ±.5
2.9 ±.4 6.9 ±.8
Rodale Mix
2. 0 N
3. Blood meal
4. Fish
2.4 ±.6
2.2 ±.3
3.1 ±.4
6.8 ±.7
7.5 ±.5
8.1 ±.9
1.7 ±.3 7.3 ±.7
2.9 ±.7 6.5 ±.74
2.4 ±.4 7.7 ±.9
Sunshine Mix
5. 0 N
6. Blood Meal
7. Fish
1.6 ±.5
3.0 ±.3
2.2 ±.4
6.9 ±.5
7.6 ±1.4
7.3 ±1.1
-
ANOVA (full model Pr>F)
Myc
Tmt
MXT
0.9374
0.0324
0.8615
0.7956
0.7435
0.5358
Termination after 5
harvests due to late
blight.

55. Tomato cv. BHN yield (conv. farm)
Treatment
Nonmycorrhizal
1. Conv
Rodale Mix
2. 0 N
3. Blood meal
4. Fish
Sunshine Mix
5. 0 N
6. Blood Meal
7. Fish
Marketable
(kg/3 plants)
Mycorrhizal
1. Conv
15.5 ± 2.3
15.4 ± 1.7
16.5 ± 1.6
15.8 ± 1.4
14.9 ± 1.6
20.7 ± 2.6
19.5 ± 1.5
ANOVA (full model Pr>F)
Myc
0.3353
Tmt
0.2038
MXT
0.4535
19.8 ± 1.2
Rodale Mix
2. 0 N
3. Blood meal
4. Fish
18.2 ± 2.2
16.3 ± 1.3
18.0 ± 0.9
Sunshine Mix
5. 0 N
6. Blood Meal
7. Fish
15.6 ± 1.2
18.0 ± 1.6
18.5 ± 1.9
No early termination

56. Using the inoculum in the field

General
considerations:



Responsiveness of
the plant
Health of the
background
population of AM
fungi
Available
Phosphorus level in
the soil




Mustards, spinach
are not mycorrhizal
Generally inversely
proportional to the
fineness of the
roots
Hard to measure
Critical level >50
ppm, but varies

57. Health of background AM fungus
population

58. Is this inoculum effective?

59. Potatoes 2002
Y ie ld (g p e r p la n t)
700
600
Conventional
Compost
500
400
300
200
100
0
Control
MYKE
On-farm
cv. Superior

60. Total yield of potatoes- 2003
Y ie ld (g p e r 3 p la n ts )
1400
Compost
Conventional
1200
1000
800
600
400
200
0
Control
MYKE
OF-YCC
Treatment
OF-DMLC

61. Potatoes
Yield (kg per 4m row)
Cultivar
Red Norland
Red Gold
Blue
Yukon Gold
Mycorrhizal
6.1
9.5
6.0
4.9
±
±
±
±
0.5
0.3
0.2
0.3
Nonmycorrhizal
4.9
8.5
5.4
5.0
±
±
±
±
0.2
0.2
0.7
0.4
Somerton Tanks Farm, Philadelphia, PA 2005
Response
24%
12%
12%
-0.9%

62. Strawberry (cv. Chandler)
Yield (kg per 10 plant subplot)
Mycorrhizal
Nonmycorrhizal
5.50 ± 0.15
4.71 ± 0.32
Response
Shenk’s Berry Farm, Lititz, PA 2005
17%

63. Tomatoes
Cultivar
Daybreak
Empire
Florida
San Marzano
Yield (kg per 4 plant subplot)
Mycorrhizal
Nonmycorrhizal
24.1 ± 0.8
30.0 ± 1.1
22.9 ± 1.1
26.5 ± 0.9
30.0 ± 1.7
20.3 ± 0.6
(kg per bed)
156.1 ± 9.2
154.1 ± 11.9
Response
-9%
0%
12%
2%
Eagle Point Farm, Kutztown, PA and Covered Bridge Farm, Oley, PA 2005

64. Yield response of bell peppers, Eagle Point Farm, Kutztown PA
Cultivar
2005
2006
2007
2008
2009
2010
2011
Boynton Bell
10.7
11.4
-0.05
14.0
9.4
Colossal
3.4
24.7
0.7
8.4
Delirio
15.4
Green Puffin
-1.3
King Arthur
10.7
Lafayette
8.1
-6.4
-1.0
3.5
-7.0
-8.0
9.6
Orange Sun
0.2
Queen
-1.2
Revolution
-3.1
-0.3
8.1
Valencia
3.3
6.5
-1.9
12.0
11.9
Whopper
-0.7
-5.1
X3R Red Knight
7.7
X3R Wizard
1.1
-2.1
10.2
6.0
____________________________________________________________________________
1
Mycorrhizal Yield Response= 100% x ((Myc-Nonmyc)/Nonmyc)

65. Leeks cv. Lancelot
Shenk’s Berry Farm 2009

66. Inoculation of sweet potatoes with AM
fungus inoculum produced on-farm

Inoculation method

Inoculum into
planting hole


2009, 2010
Inoculate potting
media and grow in
GH for 2 wks

2012, 2013

67. Sweet potatoes, cv. Beauregard
YEAR
2009
2010
2012
2013a
2013b
% increase
14.3
9.1
6.5
7.9*
7.7*
*= cv. Covington