EVALUATING BIODEGRADABLE

MULCHES FOR HIGH TUNNEL TOMATO PRODUCTION:

A MULTI-FACETED APPROACH Jeremy S. Cowan

Department of Horticulture and Landscape Architecture, Washington State University, WSU Mount Vernon NWREC, 16650 State Route 536,Mount Vernon, WA 98273

Evaluating Biodegradable Plastic Mulches for Use in

High Tunnel Tomato Production

Effects of BDM on tomato yield and fruit quality oBrix, Juice, Acidity, pH, Firmness, *Phenolics,

*Lycopene

Visual ratings of BDM degradation and image analysis Calibrate visual assessments w/ image analysis and

compare with physical properties to determine efficacy for measuring loss of BDM integrity

Post-tillage degradation in the soil Using photographic image analysis to measure

number and size of mulch fragments in the soil every 3 months

Fruit Quality Assessments

Measurement High Tunnel Open Field P-value

Juice 94.40 a 94.08 b 0.0080

oBrix 4.72 b 4.98 a 0.0007

pH 4.17 a 4.09 b 0.0330

Acidity 0.364 b 0.404 a 0.0001

Lycopene 10.8 a 8.2 b 0.0008

No significant mulch effect in 2011 on any fruit quality parameter

No location effect on firmness or β-carotene

Table 1. Comparison of tomato yield in each field location (HT and OF) in Washington in 2011.

Table 2. Comparison of tomato yield by mulch treatment in Washington in 2011

Location Total No. Total Wt. (kg)Marketable %

(No.)Marketable %

(kg)

High Tunnel 88.5 a 25.6 a 57.3 59.4

Open Field 20.8 b 4.1 b 49.3 51.8

P = (0.05) 0.0007 0.0041 0.1224 0.2367

Mulch Total No. Total Wt. (kg)Marketable %

(No.)Marketable %

(kg)

BioBag 56.5 a 15.2 a 46.6 bc 50.0 b

BioTelo 62.3 a 16.5 a 49.0 b 50.4 b

Spunbond 47.8 b 13.9 b 52.8 b 54.2 b

Black Plastic 59.8 a 15.8 a 36.5 c 38.6 c

Bareground 55.3 ab 15.1 ab 68.7 a 71.7 a

WeedGuardPlus 46.6 b 12.7 b 66.4 a 68.5 a

P = (0.05) 0.0036 0.0259 <0.0001 <0.0001

Rips, tears, and holes are counted twice monthly and apercent rating assigned based on exposed soil

Mulch Visual Assessments

Table 3. Comparison of area under mulch degradation progress curve (AUDPC) values in Washington in 2011

Treatment% Degradation

AUDPCLocation  

High Tunnel 357 b

Open Field 1367 a

P = (0.05) 0.0002

Mulch  

BioBag 927 b

BioTelo 966 ab

WeedGuardPlus 2220 a

Spunbond 85 d

Black Plastic 112 c

P = (0.05) <0.0001

Collecting mulch samples at “Final-Harvest” 25 Oct. 2011

Digital imaging of mulch samplesTransformation to monochromatic

imagesHistogram of luminosity is obtainedCompare area under histogram curves

of BDM samples at Times 1 – 3 with visual assessments and physical properties data to establish correlation coefficients

Image-based Analysis of BDM Degradation

Collecting post-tillage soil samples at 10 Nov. 2011

Soil sampling (known volume) every 3 months

Mulch fragments removed by hand and using sieves

Cleaned samples photographedUse ImageJ (NIH) to count and

measure mulch fragments to obtain average number and size per volume soil

Image-based Analysis of Post-tillage Degradation

Current StatusYear 1 completeYear 2

Photographing BDM samplesMeasuring fruit total phenolicsTill-down sampling - ongoing

Year 3Protocols for image analysis being

refinedPlanning field season

Many Thanks to:Carol MilesKaren Leonas, Debbie Inglis, Preston

Andrews, & Jessica GoldbergerJonathan Roozen, Babette

Gunderson, Karen Hasenoehrl, and the MV Veg Hort Team and Grad Students

Hang Liu and the Leonas’ LabThe rest of the SCRI Team

Lightbox

Image Analysis – IR Capture

Image Analysis – Cropped

Image Analysis – Isolate Red Channel

Image Analysis – Invert Colors

Image Analysis – Subtract Background

Image Analysis – Subtract Background

Image Analysis – Histogram

Till Down – Collecting mulch fragments

Till Down – Image Capture

Till Down – Convert to B&W (Binary)

Till Down – Analyze Particles

Till Down – Analyze Particles