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PRINCIPLES OF HEAT STRESS REDUCTION AND LIGHT
ENHANCEMENT IN ORCHARDS USING REFLECTIVE MATERIALS
Michael GlennSoil Scientist
USDA-ARS, Appalachian Fruit Res. Station, Kearneysville, WV
What is a ‘Particle Film’?
• A microscopic layer of mineral particles
Particle Film
Plant Surface
• allows water and carbon dioxide to pass through the film
After initial application After 24 hours
Stomates are not blocked
Reflective surfaces are common plant adaptation
• Plants “use” pubescence and cuticular waxes to reduce environmental stresses and reduce disease and insect damage
• Particle film technology builds on this strategy of a reflective plant surface that repels insects
Particle Film Technology• Based on a chemically inert mineral, Kaolin. Used in paints, plastics, cosmetics, pharmaceuticals,food. •Registered with EPA in 1998 as “Surround” for insect control.•Exempt from Tolerance and is approved for organic use with a 4 hour REI.• Surround WP is used in conventional (85%) and organic (15%) fruit production; valuable for transition from conventional to organic crop production.
• Reduced Insect Damage–Protection against insects in a wide range of
crops• Horticultural Benefits
–Sunburn reduction–Heat stress reduction
»Increased photosynthesis»Decreased water stress
–Improved fruit quality»Improved fruit color
Particle Film Technology
Multi-functional Tool for Agricultural Production
• Particle Film Development
• First Spray
• Second Spray
• Third Spray
SurroundWP
•Mechanisms that reduce sunburn damage
1) Reduced temperature2) Reflection of IR 3) Reflection of UV 4) Reduced visible light
Fruit temperatures demonstrate infrared reflection and temperature reduction
Chile
Surround
The processed kaolin is highly reflective of all UV wavelengths
Visible RadiationUv-A and Uv-BRadiation
Radiation levels at solar noon
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
200 300 400 500 600 700 800Wavelength (nm)
Rad
iatio
n (W
/m2)
Aug 31 WVJan 13 Talca
UVb
UVa
Sunburn damage (%)
Wenatchee, WAUSA
Nelson,New Zealand
Surround-WP 2 1
Untreated 11 22
Generally, sunburn is reduced approximately 50% or more
Aerial Application of Surround WP to Bananas for Sunburn Control in Honduras
How do particle films alter light transmission and scatter?
Laser on glass Laser on particle film
Whole Canopy Photosynthesis 2003
0
10
20
30
40
50
60
651
1451
2251 65
114
5122
51 651
1451
2251 65
115
5123
51 751
1551
2351 75
115
5123
51 751
1551
Hour
Car
bon
Ass
imila
tion
(g C
O2/
hr/tr
ee)
UntreatedSurround
15 August2003 16 2120191817
Mean fruit weight (g)Control 110 b
Surround 117 a
Photosynthesis is fundamentally limited by 2 factors:
• Carbon dioxide levels within the leaf• Light reaching the leaf surface
– Particle films reduce light (5-10%) but increase internal leaf carbon dioxide.
– The balance between these 2 limiting factors determines if photosynthesis will increase or decrease.
Transmission of PAR through particle films of various kaolin sources.
0
20
40
60
80
100
120
0 5 10 15 20Residue (g/m2)
Tran
smitt
ance
(%)
after Glenn et. al. (1999)after Abou-khaled et. al. (1976)after Jifon and Syvertsyn (2003)
Effect of particle film on carbon assimilation in apple and internal carbon dioxide concentration
-200
2040
6080
100120
140160
180
6 8 10 12 14 16 1818 Aug (HR)
Ci
(Int
erna
l lea
f CO
2 le
vel)
3% 12% Control
12%
Control
Effect of Surround-WP on fruit weight (g/fruit) of ‘Empire’ apples
Treatment 1998 1999 2000 2001Surround WP 117 a 164a
105 b(0.12)
134aControl
124a116b139b 131b
(0.09)
Treatment 2002 2003 2004 2005Surround WP 144 117a
144 ns138a
Control170a153b110b 123b
Effect of ‘Surround’ on fruit color (2005)
Control Surround 3% Surround 12%
Increased light scatter within the plant Increased light scatter within the plant canopycanopy
Reflection of light from the orchard floor
Light levels in an apple orchard West 1m
0
1
2
3
4
5
6
7
8
800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900
Hour
% o
f inc
omin
g P
AR
Control
aluminized plastic
particle film material
Effect of Mylar film and particle film on ‘Empire’ apple color development
TreatmentFruit weight
(g) hue°
Control 131 b
136 a
132 b
72aControl+ ground particle
film 60b
Aluminized plastic 63b
Lower hue angle indicates increased red color
Amount and quality of light reflected from grass, reflective particle films and an aluminized
reflective plastic film.Treatment Reflected
photosyntheticallyactive radiation
Ultraviolet radiation (315 to 400 nm)
Red/Far Red ratio (660/730 nm)
(% of incoming)Grass 5.1 2.0 0.12FTKS 10.7 8.1 0.38GCO 11.1 8.0 0.37Reflective film (new)z
65.5 56.9 1.27
Reflective film (old) y
49.3 46.8 1.13
Full sunlight 1.33
Effect of Mylar film and particle film on ‘Empire’ apple color development
TreatmentFruit weight
(g) hue°
Control 131 b
136 a
132 b
72aControl+ ground particle
film 60b
Aluminized plastic 63b
Lower hue angle indicates increased red color
• The Particle Film improves red color development in the unexposed surfaces of apples– Site and region specific– Cultivar specific
Insects Crops Pear Psylla ApplePear Rust Mite PearApple rust mite PeachCodling Moth CherryLeafhoppers AlmondPlum Curculio Walnut Apple Maggot PecanThrips GrapeLeaf Rollers BerriesJapanese Beetle CornMediteranean Fruit flyOlive fruit fly OliveGlassy-Winged Sharpshooter Citrus
Blueberry Maggot Melons
Successes of Particle Films
Summary of Particle Film Technology
• Horticultural Benefits– Sunburn reduction– Heat stress reduction
» Decreased water stress may improve fruit quality and yield
– Improved fruit quality
» Improved fruit color
Multi-functional tool for agricultural production • Reduced Insect Damage
– Many classes of insects are repelled in a wide range of crops
• Potential Obstacles to Use– Washoff of mineral
residues from fruit– Washoff by rain and
wind– Interference with
biological control