Light effects during pre- and postharvest stages to improve

nutrition of high tunnel vegetables

Kelly Gude, Ph.D. student, Horticulture and Natural Resources

Introduction

• Light intensity and spectral quality impact the accumulation of several phytochemicals (nutritional quality) (Luthria et al., 2006; Oh et al., 2009).

• However, UV-stabilized polyethylene (poly) is common to maintain its condition, which reduces spectral quality by blocking UV-B and reducing light intensity by 15-20% (Rajapakse and Shahak, 2014).

OBJECTIVE: Evaluate the impact of different poly films on spectral quality and a simulated movable tunnel on light intensity regarding photosynthesis, temperature, crop yield, storage life, and nutritional quality of tomato and lettuce.

2017

July - Oct., 2017

May, 2017

Nov., 2017

Oct., 2017

Harvest Fall Lettuce

Transplant Lettuce

May, 2018

Apr., 2018

Harvest Spring Lettuce

Transplant Lettuce

Harvest BHN 589

Plant Tomato BHN 589

July - Oct., 2018

May, 2018

Harvest BHN 589

Plant Tomato BHN 589

May, 2018

Harvest Movable Tunnel Lettuce

Nov., 2018

Oct., 2018

Harvest Fall Lettuce

Transplant Lettuce

May, 2019

Apr., 2019

Harvest Spring Lettuce

Transplant Lettuce

20192018

Materials and Methods

Materials and Methods

3 12’

130’20’5’

14265

4

1

Rep.3

Rep.4

Rep.2

Rep.1

S

W

6 5324

3 65412

5 2361

…………………………………………10’

BU

FFER

…………………… ……………………

BU

FFER

BU

FFER

Rep.1 Rep.3 Rep.4

BU

FFER

BU

FFER

Rep.2

7

1. Standard Poly

2. Std. Poly with removal 2

weeks prior to initial harvest3. Luminance (diffuse) poly4. Clear poly

5. UVA + UVB Blocking

6. 55% shadecloth

7. Open field

Materials and MethodsYield: weekly harvest for tomatoTomato: Total and Marketable (lbs/plant), Total and Marketable (lbs/sample), Marketability

(Weight %), Biomass samples (g) (9/14)Leaf Lettuce: Total and Marketable Head Weight (g/head)Movable Tunnel Leaf Lettuce: Total and Marketable Head Weight (g/head)

Treatment Effect: measured thrice one week prior to harvest1. Chlorophyll content (SPAD, light transmittance/absorbance), UV-A, UV-B (8/8)2. Canopy and Soil temperature (temperature °F taken in 30 minute increments with

temperature probes)3. Photosynthesis (CI-340) PAR, leaf temp., internal CO2, net photosynthesis rate, transpiration

rate, leaf stomatal conductance rate

Materials and Methods

Storage Quality and Nutritional Quality:1. Water loss throughout storage (%), texture (N and sample wt.), dry matter content (%)2. Phenolic Acid/ Flavonoid (coumarin, chicoric acid, chlorogenic acid, caffeic acid, ferulic acid,

rutin, kaempferol, naringenin, quercetin), 1. Vitamin C (µg AA/100g) in tomato2. Anthocyanin in Lettuce

Materials and Methods

Breaker

Light Red Maturity, measured:(1) on the day of harvest and (2) ‘mature red’ maturity

Breaker Maturity, measured:(1) on the day of harvest, (2) ‘light red’ maturity, and (3) ‘mature red’ maturity

Determined by a* value ((-)greenness to (+)redness)

Light Red

Breaker Mature Red

-4.91 22.90 27.28

Results – Tomato

b

a

b b b

c

0

200

400

600

800

1000

1200

1400

1600

1800µ

mo

l/m

2 /s

PAR (P < 0.0001)

Photosynthetic analysis of BHN-589 in 2018. Photosynthetic Active Radiation (PAR) (µmol/m2/s) measured 8/1, 8/3, 8/5.

*Representative of open field

Results – Tomato Tomato 2017

TRTsTotal Marketable Total Marketable Marketabilitylbs/plant lbs/plant lbs/sample lbs/sample Weight (%) Number (%)

Standard 16.51 a 12.97 0.41 0.40 78.94 80.43

Removal 16.02 a 11.66 0.44 0.44 72.80 72.67Diffuse 17.03 a 13.26 0.42 0.42 77.79 78.00Clear 17.29 a 12.93 0.45 0.46 73.91 73.00

UVA/B Block 15.25 ab 11.83 0.41 0.42 77.69 76.43

Shade 10.13 b 8.71 0.36 0.36 85.55 84.72

P < 0.01

Tomato 2018

TRTsTotal Marketable Total Marketable Marketabilitylbs/plant lbs/plant lbs/sample lbs/sample Weight (%) Number (%)

Standard 12.89 ab 10.54 ab 0.33 ab 0.34 81.84 79.35 ab

Removal 11.72 ab 8.79 ab 0.30 b 0.31 75.89 73.13 b

Diffuse 15.04 a 12.14 a 0.35 ab 0.35 80.81 80.81 abClear 15.62 a 12.15 a 0.36 a 0.36 77.45 76.73 ab

UVA/B Block 14.24 a 11.06 ab 0.37 a 0.36 77.65 78.66 ab

Shade 9.48 b 7.94 b 0.33 ab 0.33 83.96 85.52 a

P < 0.01 < 0.01 0.01

Table 1. Yield analysis of all fruit from weekly harvests in 2017 (7/10-10/3). Treatments marked with different letters are significantly different (α < 0.05). Tukey’s HSD.

Results – Tomato

Vitamin C, measurement of ascorbic acid content of ‘Light Red’ and ‘Breakers’ mature groups.

0

5

10

15

20

25

1 2 3 4 5 6

Asc

orb

ic A

cid

(µ

gAA

/10

0g)

Light Red Maturity

Light Red Mature Red

0

5

10

15

20

25

1 2 3 4 5 6

Breaker Maturity

Breaker Light Red Mature RedStandard | Removal | Diffuse | Clear | | Shade SP SP2W DP CP UVAUVB SCSP

UVA/B Block

Standard | Removal | Diffuse | Clear | | ShadeUVA/B Block

Summary – Tomato Yield• 2017, statistically similar total yield (lbs/plant) for all treatments except

the shade treatment produced less total yield.• 2018, statistically similar total yield (lbs/plant) for treatments diffuse,

clear, and UVA/B block with shade producing less total yield.• Although total yield was higher in 2017, marketable yield was

similar between both years, while marketability (weight and number %) was greater in 2018.

Photosynthesis and Nutritional Analysis• Removal treatments with highest PAR, other treatments are significantly

similar except for shade• Chlorophyll and ascorbic acid content was statistically similar across

treatments.

Results – Lettuce

49

51

53

55

57

59

61

12:00 AM 2:00 AM 4:00 AM 6:00 AM 8:00 AM 10:00 AM 12:00 PM 2:00 PM 4:00 PM 6:00 PM 8:00 PM 10:00 PM 12:00 AM

1 2 3 4 5 6 7

Soil temperature of lettuce in 2017 (10/7-11/17).

Fall, 2017

Trt Soil Temp. (°F) Canopy Temp. (°F)

1. Standard 56.39 BC 50.93 A

2. Removal 54.57 D 50.60 AB

3. Diffuse 57.26A 50.66AB

4. Clear 57.19 A 48.79 C

5. UVA/B Block 56.87 AB 49.42 BC

6. Shade 56.08 C 48.80 C

*Open Field 52.81 E 50.80 A

P <.0001 <.0001

Diffuse and Clear Poly. with higher soil temperatures than other treatments (Std., Removal, Shade, Open). Tukey’s HSD.

Results – Lettuce (Fall, 2017)

Yield analysis from fall harvests in 2017 (11/3-11/17) *Open field not statistically analyzed

Red Leaf

Trt Fresh Wt.(g/plant)

Core length(cm)

Leaf Area(cm2)

Moisture Loss D5 (%)

Dry Matter (%)

Standard 51.93 A 17.26 A 141.5 A 11.48 7.71

Removal 51 A 16.06 ABC 120.28 AB 11.53 7.56

Diffuse 52.13 A 16.71 ABC 120.59 AB 11.17 7.27

Clear 45.57 AB 15.58 BC 105.32 AB 11.21 7.22

UVA/B Block 39.58 AB 15.16 C 96.04 B 15.04 7.77

Shade 29.61 B 16.18 ABC 99.1 B 16.56 7.91

*Open Field 14.1

P < .01 < .05 ns ns

Green Leaf

Trt Fresh Wt.(g/plant)

Core length(cm)

Leaf Area(cm2)

Moisture Loss D5 (%)

Dry Matter (%)

Standard 68.67 A 18.43 127.22 18.23 AB 8.92

Removal 79.67 A 18.13 139.27 15.97 B 8.82

Diffuse 68.69 A 18.31 142.4 19.39 AB 8.60

Clear 62.44 AB 17.48 136.07 18.78 AB 8.64

UVA/B Block 56.65 AB 16.67 124.92 19.49 AB 8.68

Shade 40.68 B 17.52 120.06 25.5 A 8.14

*Open Field 17.51

P < .01 ns ns < .1 ns

Results – Lettuce (Spring, 2018)Spring, 2018

Trt Red Leaf Fresh Wt. (g/head)

Green LeafFresh Wt. (g/head)

Standard 156.54 137.88

Removal 153.67 158.83

Diffuse 158.86 145.54

Clear 149.06 136.97

UVA/B Block 138.63 131.37

Shade 114.63 115.37

*Open Field 10.74 35.87

P ns ns

Yield analysis from spring harvests in 2018 (5/3-5/10).*OF not statistically analyzed **NS between treatments for quality parameters

Results

40

42

44

46

48

50

52

1 2 3 4 5 6L* (

ligh

tnes

s(+)

> d

arkn

ess(

-))

D0 D5

Color measurements from Red Leaf spring, 2018 (5/3-5/10). Analysis days analyzed separately, L*D0 NS, L*D5 P < 0.05

1 2 3 4 5 6 7Standard Open FieldDiffuse Clear UVA/B Block ShadeRemoval

Standard | Removal | Diffuse | Clear | | ShadeUVA/B Block

Results

-14

-12

-10

-8

-6

-4

-2

0

1 2 3 4 5 6

a* (

gree

nn

ess

(-)

< re

dn

ess

(+))

D0 D5

Color measurements from Red Leaf spring, 2018 (5/3-5/10). Analysis days analyzed separately, a*D0 P < 0.01, a*D5 P < 0.01

1 2 3 4 5 6 7Standard Open FieldDiffuse Clear UVA/B Block ShadeRemoval

Standard | Removal | Diffuse | Clear | | ShadeUVA/B Block

Summary – Lettuce Leaf Lettuce • Yield: standard, removal, and diffuse with the greatest lettuce yield

(g/plant) for both Red and Green leaf in fall, 2017.• Nutritional Analysis: Treatments removal and clear with darker,

redder color valuesTBD on correlation to nutrient accumulation

• Temperature: diffuse and clear poly had statistically higher soil temperatures in comparison to the rest (P < .0001)

12’

2’

North

66’

Standard48 h Removal1 wk Removal2 wk Removal

4’

Movable Tunnel

Results – Movable Tunnel

Green Leaf

TRTs Fresh Wt. (g/head)

Core Length (cm)

Leaf Area(cm2)

Moisture Loss D5 (%)

Dry Matter (%)

Standard 105.97A 17.31 A 120.30 18.23 7.60 AB

48 h removal 122.96A 17.98 A 114.88 19.52 6.26 B

1 wk removal 103.05AB 16.83 A 103.55 19.31 7.31 AB

2 wk removal 69.60B 13.96 B 82.87 17.16 8.47 A

P < .05 < .05

Red Leaf

TRTs Fresh Wt. (g/head)

Core length(cm)

Leaf Area(cm2)

Moisture Loss D5 (%)

Dry Matter (%)

Standard 76.69 15.90 a 140.20 A 14.65 7.34 A

48 h removal 88.11 14.98 ab 107.14 C 25.90 5.82 B

1 wk removal 97.36 15.19 ab 127.63 AB 29.56 5.72 B

2 wk removal 67.71 14.41 b 111.75 BC 29.39 6.27 AB

P < .1 < .01 < .01

Yield: 2 week removal (plants exposed to full sun 14 days prior to harvest) resulted in less yield (g/plant) for Red and Green leaf

AcknowledgementsMANY thanks to Olathe Horticulture Recreation and Extension Center (OHREC) team for harvest and management support (Paul Anderson, Cassidy Fleck, Ashlee Skinner, Carley Estes, Kim Oxley, Brian Boutte, Vicente Mascote, Tracy Oelschlaeger, Claire Barnhart)

MANY thanks to KSU-Olathe Postharvest Team for analysis day all-hands-on-deck support (Joe Rundquist, Tricia Jenkins, Kostas Batziakas, Helena Chiebao)