krishna nemali knemali@purdue
TRANSCRIPT
Topics :
• Production Systems• Substrate• Spacing• Varietal Selection• Germination• Nutrients• Temperature• Light• Winter Production
HeatingSupplemental Lighting
Deep Water CultureNutrient Film Technique
Hydroponic Production Systems
Flood and Drain Tables
3-inches
12-inches
Aeroponic Towers
Aeroponic Production Systems
Aeroponic Tower
Production Systems
Flood Table
020406080
100120140160
Flood Table Nutrient FilmTechnique
Aeroponics Tower
Yield(grams per square feet)
0
0.5
1
1.5
2
2.5
Flood Table Nutrient FilmTechnique
Aeroponics Tower
Water Use (liters per week per square feet)
Production systems mostly differ in water use
Hydroponic Substrates
Peat Rockwool
Peat substrates resulted in faster growth
PeatRock wool
Spacing (36 plants/m2)1 m
1 m
6”
6”
Spacing: Fixed NFT Benches
8-inches6-inches
3 plants/ft2 or 32 plants/m2
Week 1 Week 2 Week 3 Week 4
Spacing: Sliding NFT Benches
Week 1 Week 2 Week 3 Week 41-inch 3-inch 6-inch 8-inch
Lettuce Varietal Trial
• Keep humidity high and plugs moist during germination
• Use a dilute fertilizer solution (EC of 0.5 to 0.75 dS/m)
• Light intensity can be low (100 to 150 µmol/m2/s) during the initial week
• Preferred germination temp ~ 70 F or 21 C• Seedlings may need to be thinned, earlier
preferred• Transplant seedlings prior to leaf overlap
Germination
Nutrient requirement(combined data from 8 lettuce varieties and 2 production systems )
02468
1012141618
0 50 100 150Yiel
d ( g
ram
s per
pla
nt)
Nitrogen Concentration (ppm)
Managing recycled fertilizer solution
* Control treatment received freshly prepared solution twice a week
Negative effects of recycling appears after two weeks
Negative effects can be reduced by discarding recycle solution after two weeks or using RO water
Air/solution at 60 °F Air/solution at 70 °F
Optimum greenhouse temperature
Light requirement
• Heating and supplemental lighting are required
• Energy costs for heating and supplemental lighting affect profits
• Productivity and energy efficiency should be increased for profits
Greenhouse production during winter
Greenhouse was maintained at cooler temperature to reduce heating costsSolution temperature was increased from 60 to 71°F
Maximize heating efficiency using root zone heating
Greenhouse 60/50 FHeated Solution (70 F) Unheated Solution (60/50 F)
Plant growth was better under flood tables than NFT when warm solution was supplied to roots
Production system effects on root zone heating
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23
1 13 25 37 49 61 73 85 97 109
121
133
145
157
169
181
193
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265
277
289
301
313
325
337
349
361
373
385
397
409
421
433
445
Tem
pera
ture
(°C)
Time (hours from start)Air Reservoir solution NFT solution Flood table solution
Full spectrum Red : Blue T8
Butterhead
Romaine
Red leaf
Green leaf
Lettuce growth is highly influenced by light spectrum
Supplemental lighting at nighttime
White R : B No SL
Increased productivity under Red (90%) : Blue (10%)
Project Sponsors