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