berks co cons district 2 26 2015
TRANSCRIPT
Management and Utilization of Arbuscular Mycorrhizal Fungi
David DoudsUSDA-ARS Eastern Regional Research Center
Introduction Structure Function
Management of AM fungi
On-farm production of inoculum
Field trials
Arbuscular Mycorrhizal [AM] fungi Arbuscule
(L. “small tree”)
Mycorrhiza (Gr. “fungus root”)
Development of an arbusculeKinden and Brown, 1979
Function of mycorrhizas
Green ash (Fraxinus pennsylvanica)
Other benefits
To the plant: Enhanced water relations Enhanced pest resistance Enhanced salt stress resistance
To the soil: Stability of soil aggregates (glomalin)
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)
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
1. Fertilization: effect of high nutrient addition upon the fungus (colonization and sporulation)
Response of colonization to P level for tomato, pepper, and bahiagrass
0 10 20 30 40 50 60 700
10
20
30
40
50
60
70Tomato (Crista)
Pepper (Lafayette)
Bahiagrass
P concentration (ppm)
Ro
ot
len
gth
co
lon
ize
d (
%)
2. Pesticide application
Fungicides- direct negative effects upon AM fungi, e.g. Benomyl
Herbicides- indirect effect via removal of potential host plants Diversity of AM fungus community parallels
diversity of the plant community Less carbon available for growth/reproduction
3. 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
Over wintering crop of hairy vetch increased the AM fungus inoculum present in the soil
Other situations related to bare soil Flooded soil syndrome Stale weed seed bank treatments Long term bare fallow
4. 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?
5. Tillage Tillage interferes with
two functions of the extraradical mycelium of AM fungi:
1. As infective propagules
2. As the nutrient uptake organ
6. Farming system The Farming Systems Trial®
Soils from the organic rotations have a higher AM fungus inoculum potential
… and greater spore populations
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.
II. Inoculation with AM fungi
Options:a. commercially available inoculab. produce it yourself
Target farmers:vegetable producers who grow their own seedlings
labor intensive farms
On-farm inoculum productionMaterials
compostvermiculitegrow bags
Transplant:Bahiagrass (Paspalum notatum) seedlingsprecolonized by AM fungi
Weed and water for one growing season
Inoculum is ready for use the following spring
7 gallon “grow bags”
Inoculum of AM fungi
Spores
Infective hyphae
Colonized roots
Production of propagules of AM fungi in 1:4 [v/v] mixtures of yard clippings compost and vermiculite. Results of MPN bioassays.
Inoculated PropagulesAM fungus cm-3 section (x106)
Glomus 120 13.5mosseae
Glomus 750 84.4etunicatum
Glomus 120 13.5geosporum
Glomus 365 41.1claroideum
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
Modifications to on-farm system
Diluents Field soil
Is this inoculum effective?
Considerations for inoculum utilization Factors influencing response to
inoculation: Responsiveness of the plant Soil available P level (> 50ppm) Vigor/ health of the indigenous population of
AM fungi
The goal is to outplant a seedling with a functioning symbiosis already in place
Control MYKE On-farm0
100
200
300
400
500
600
700Conventional
Compost
Yie
ld (
g p
er
pla
nt)
Potatoes 2002
Total yield of potatoes- 2003
Control MYKE OF-YCC OF-DMLC0
200
400
600
800
1000
1200
1400CompostConventional
Treatment
Yie
ld (
g p
er 3
pla
nts
)
Potatoes Yield (kg per 4m row)
Cultivar Mycorrhizal Nonmycorrhizal Response
Red Norland 6.1 ± 0.5 4.9 ± 0.2 24%Red Gold 9.5 ± 0.3 8.5 ± 0.2 12%Blue 6.0 ± 0.2 5.4 ± 0.7 12%Yukon Gold 4.9 ± 0.3 5.0 ± 0.4 -0.9%
Somerton Tanks Farm, Philadelphia, PA 2005
Strawberry (cv. Chandler)
Yield (kg per 10 plant subplot) Response
Mycorrhizal Nonmycorrhizal
5.50 ± 0.15 4.71 ± 0.32 17%
Shenk’s Berry Farm, Lititz, PA 2005
Tomatoes Yield (kg per 4 plant subplot)
Cultivar Mycorrhizal Nonmycorrhizal Response
Daybreak 24.1 ± 0.8 26.5 ± 0.9 -9%Empire 30.0 ± 1.1 30.0 ± 1.7 0%Florida 22.9 ± 1.1 20.3 ± 0.6 12%
(kg per bed)San Marzano 156.1 ± 9.2 154.1 ± 11.9 2%
Eagle Point Farm, Kutztown, PA and Covered Bridge Farm, Oley, PA 2005
Leeks Shenk’s Berry Farm 2009
Sweet potatoes, cv. Beauregard
YEAR % increase2009 19.22010 9.42012 7.02013 8.22014 7.1
Avg 9.8
Eagle Point Farm, Kutztown, PA
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 ____________________________________________________________________________ 1Mycorrhizal Yield Response= 100. (Myc-Nonmyc)/Nonmyc.