2014 National Sustainable Strawberry Initiative Project Leader Meeting

1. Off-Season Hydroponic
Strawberry Production
Chieri Kubota and Mark Kroggel
School of Plant Sciences
University of Arizona

2. December, Japan

3. January, Mexico

4. Our goal
• To reintroduce AZ
strawberry production
in a more sustainable
system
• Winter production
(Harvesting from
November to April)
• To develop
comprehensive
information resources

5. Key Technologies
• Ever-bearing cultivars (no need to induce flowers
to start producing early)
• Aggregate hydroponics using raised troughs with
selected substrate mix (high porosity) – Daily
monitoring/adjustment of EC, pH, and %drainage
• Night time VPD (RH) control (high RH for 3 hrs)
• Glazing with high UV transmission (ETFE)
• Daylength extension lighting (3 mmol m-2 s-1) for
facultative long-day response

6. Hydroponic system at UA
• Substrate system in raised troughs

7. Styrofoam trough system (Ishiguro Nozai Co.)
Substrate volume: 22 L per meter
Substrate volume per plant: 2.4 L (>2 L is recommended)
Composition: 50% Perlite + 25% Coco coir + 25% Peat
(Air porosity: 15.6% @4.5 inch column)
(Ishiguro-Nozai Co.)

8. www.bato.nl
Hanging bucket system (Bato Plastics)
Volume: 11 L per bucket
(2.8 or 3.7 L per plant at 4 or 3 plants per bucket)

9. Night time VPD control for tipburn
Inducing high xylem pressure at night (inducing guttation)
Under-trough misting (intermittent) to achieve 95% RH inside the
canopy for 3 hours

10. Glazing with high UV transmission
• ETFE (ethylene
tetrafluoroethylene)
• High UV and PAR
transmission
• Converting direct
light to diffuse light
• Long life

11. Extending the day length or interrupting the night
(Needed for cultivars that are extremely sensitive to day length to
enter dormancy) Target light intensity: 2-3 mmol m-2 s-1
Commercial greenhouse with NI lighting
UA Greenhouse

12. January 21

13. Cultivation practices (2013-2014)
• Cultivars: Albion and Portola
• Transplants: Rooted runner plants
• Planting density: 8 or 12 plants/m2
• Transplanting: August 10th, 2013
• First harvest: September 22nd, 2013
• Nutrient solution: Yamazaki Strawberry Formula (EC = 1.0)
• Temperature setting: 25C/10C (day/night)
• Cultivation practices
– Leaf pruning
– Crown pruning (when needed)
– Drip irrigation (33 mL/plant per event; 20-30% drainage)
• Pollination: Electric pollinator

14. Off-Season Hydroponic Strawberry
Production Benchmarks
• Yield per crop: 7 kg m-2
(vs. open field yield in CA = ~3 kg m-2)
• Fruit size: 20 g per fruit
• Brix% (total soluble solids): 7%**
• Titratable acidity: 0.8% (or 8 g/L)**
**UC Davis recommendations

15. Treatments Fruit size (±S.D.)
All 24.4±1.2 g (max 52.1 g)
LD = Low Density (8 plants/m2) Bucket
HD = High Density (12 plants/m2) Bucket
Styro = Low Density (8 plants/m2) Styrofoam trough
Benchmark: 7 kg/m2
kg/m2
NS

16. Treatments Fruit size (±S.D.)
All 19.7±1.4 g (max 51.8 g)
LD = Low Density (8 plants/m2) Bucket
HD = High Density (12 plants/m2) Bucket
Styro = Low Density (8 plants/m2) Styrofoam trough
Benchmark: 7 kg/m2
kg/m2
NS

17. Fruit quality affected by cultivar and season
----- Levels of UC Davis recommendations (> 7 for Brix; < 0.8% for TA)
Albion (TSS)
Portola (TSS)
Albion (TA)
Portola (TA)

18. Greenhouse environments
Shade removal
Shade applied
Daily Light Integral (integrated PAR) Air temperature (Max, Min, Mean)

19. Root-zone pH
2nd flush1st flush 3rd flush

20. Diurnal change of strawberry Pmax
PAR = 1000 mmol/m2/s
CO2 = 380 ppm

21. A bit about economics of production
Item Tomato Strawberry Comments
Production Time 12 months (year
round)
9 months (6 months
in production)
10,000 ft2 GH
Benchmark Yield 50 kg/m2 or 10.2 lb/ft2 7 kg/m2 or 1.4 lb/ft2
Production Costs
(variable costs only)
$0.68/lb* or $6.89/ft2 $3.31/ft2** ~50% of tomato
Total Costs (including
depreciation***)
N/A $3.94/ft2** Not including GHs
Market price $2.00/lb $5.00/lb
Gross profit $13.5/ft2 $3.7/ft2 Not including
depreciation
*After the costs reported by Pena (2005) http://aggie-
horticulture.tamu.edu/greenhouse/hydroponics/economics.html
**U of AZ estimate (Tucson)
***Troughs, irrigation system, plastics and cooler (greenhouse not included)

22. Production costs (/ft2)
(10,000 feet greenhouse in Tucson, AZ)
Items Costs ($/ft2) Comments
Labor $1.54 (39%) 1,560 person-hours
Utilities - Gas $0.32 (8%) Virtual Growers
Utilities - Electricity $0.32 (8%)
Utilities - Water $0.12 (3%) Municipal water
Plants $0.13 (3%)
Substrates $0.29 (7%) Pre-mixed
Plastics $0.02 (0.5%)
Fertilizers $0.40 (10%) Yamazaki strawberry formula
Bees $0.10 (3%)
IPM $0.07 (2%)
Equipment – Amortized $0.63 (16%) Irrigation, troughs, plastics, cooler facility
Total costs $3.94 (100%)

23. Future Key Technologies needed for
Strawberry
• Soilless culture system (movable
troughs)
• Small honeybee hives
• Better tasting cultivars
• Cultivar information
(environmental physiology and
photoperiodic responses)
• June-bearing cultivars +
flowering control

24. Temperature x photoperiod
general responses of strawberry
Type Average Temperature
June-
bearing
< 5C
(41F)
5 – 12C
(41-54F)
12 – 26C
(54-79F)
> 26C
(>79F)
No flower
induction
(dormancy)
Flower induction
under all
photoperiods
Short day (8-13 h)
promotes flower
induction
No flower
induction
(critical temp
depending on
cultivars)
Ever-
bearing
< 5C
(41F)
5 – 15C
(41-59F)
15 – 30C
(59-86F)
> 30C
(>86F)
No flower
induction
(dormancy)
Flower induction
under all
photoperiods
Flower induction
under all
photoperiods, but
number of flowers
increases under
longer day
Flower
induction is
suppressed.
Strawberry production manual (Saga Prefecture AES)

25. Website: http://cals.arizona.edu/strawberry
YouTube: “Strawberry Sunrise in Arizona”
http://www.youtube.com/watch?feature=player_embedded&v=C1oSypOSrfU
AZ Strawberry Days (Dec & Feb)
K-12 Events (Nov & Apr)
Outreach activities

26. Industries in News
• Windset Farms (Delta, BC)
announced that they
introduced greenhouse grown
strawberries (3/25/2014, The
Packer)
• La Frissonnante greenhouse
(Quebec) will expand
hydroponic strawberry
production for exclusive sales to
a major grocery chain, Metro
Inc. (4/23/2014, CNW)
• A new 10-acre organic
hydroponics GH in San Quintín,
Mexico
• No Arizona greenhouses yet…
http://cnw.en.mediaroom.com
http://elvigia.net

27. Acknowledgment
UA hydroponic strawberry project is funded by
a grant from the Walmart Foundation and
administered by the University of Arkansas
System Division of Agriculture Center for
Agricultural and Rural Sustainability.
U of AZ Project Team
• Chieri Kubota
• Mark Kroggel
• Myles Lewis
• Karla Garcia Cabello
• Michael Whalen
Advisory
• Ian Justus
• Kelly Young
• Masami Ishikara
• Seiji Matsuda
Collaborators
• Mike Evans
• Shoko Hikosaka