THE GREENHOUSE EFFECT
THE INFLUENCE OF: LIGHT, WATER & TEMPERATURE
ON PLANT GROWTH
ACORN Presents: Organic Greenhouse Growers Conference
Profiting From Your Greenhouse Effect: The Essentials Of Season Extension
Debert Hospitality and Convention Centre
February 28 – 29, 2012
THE GREENHOUSE EFFECT
THE INFLUENCE OF: LIGHT, WATER & TEMPERATURE
ON PLANT GROWTH
WHAT PLANTS NEED TO GROW
NUTRIENTS
WHAT PLANTS NEED TO GROW
NUTRIENTS
WATER
WHAT PLANTS NEED TO GROW
NUTRIENTS
WATER
CO2 and O2
WHAT PLANTS NEED TO GROW
NUTRIENTS
WATER
CO2 and O2
LIGHT
WHAT PLANTS NEED TO GROW
NUTRIENTS
WATER
CO2 and O2
LIGHT
(PROPER) TEMPERATURE
WHAT PLANTS NEED TO GROW
NUTRIENTS
WATER
CO2 and O2
LIGHT
(PROPER) TEMPERATURE
(Absence Of Pests)
WHAT PLANTS NEED TO GROW
NUTRIENTS
WATER
CO2 and O2
LIGHT
(PROPER) TEMPERATURE
(Absence Of Pests)
(Nutrients, Water, & O2 Available Via a Substrate)
WHAT PLANTS NEED TO GROW
GROWING PLANTS IS BASICALLY:
“THE HARVESTING OF LIGHT”
& Rate is Temperature Dependent
Photosynthesis
NUTRIENTS
WATER
CO2 and O2
LIGHT
(PROPER) TEMPERATURE
(Absence Of Pests)
(Substrate)
WHAT PLANTS NEED TO GROW
NUTRIENTS
WATER
CO2 and O2
LIGHT
(PROPER) TEMPERATURE
(Absence Of Pests)
WHAT PLANTS NEED TO GROW
WATER
NUTRIENTS
WATER
CO2 and O2
LIGHT
(PROPER) TEMPERATURE
(Absence Of Pests)
WHAT PLANTS NEED TO GROW
CO2
O2
O2
CO2
NUTRIENTS
WATER
CO2 and O2
LIGHT
(PROPER) TEMPERATURE
(Absence Of Pests)
WHAT PLANTS NEED TO GROW
LIGHT
NUTRIENTS
WATER
CO2 and O2
LIGHT
(PROPER) TEMPERATURE
(Absence Of Pests)
WHAT PLANTS NEED TO GROW
TEMPERATURE
THE GREENHOUSE EFFECT
THE INFLUENCE OF: LIGHT, WATER & TEMPERATURE
ON PLANT GROWTH
Noggins Corner Farm
Greenwich, NS - Fall 2009
HILLENDALE PERENNIALS
Part – Time Farm Business Specializing in Landscape Perennials & Various
Other Specialty (Mainly Ornamental) Crops / Products / Services
All Direct (Retail) Marketed
Crops / Products:
•  Herbaceous Perennials (100 s of species / cv.)
•  Late Season Patio/Deck Planters (annuals)
•  Outdoor Cut Flowers (fresh & dried)
•  Christmas Decorative Products
•  Mid Season Lily Planters
•  Potted Roses
•  Culinary Herb Potted Gardens
•  Miscellaneous: Potted Dwarf Sunflowers, Potted Calla Lilies, Native
Plants, Lily Bulbs
Services:
Perennial (& Mixed) Border Designs
dried
flowers
potted
sunflowers
fresh cut
flowers
perennials
annual
planters
potted herbs
culinary
THE GREENHOUSE EFFECT
THE INFLUENCE OF: LIGHT, WATER & TEMPERATURE
ON PLANT GROWTH
WATER
Water Has 4 Main Roles (Broad Sense)
Solvent
- gases, inorganic and organic compounds are
dissolved; the medium in which they enter cells.
Reagent
-  part of many cellular reactions and processes
Structure
- present in plant cells, maintain turgor.
Coolant
- transpiration
Water
•  Quality and Quantity?
•  Too little / Too Much?
•  How Much: Crop, Stage of Growth, Outside Weather,
Season, Growing Medium, Method of Fertilization
•  How to Determine When plants Need Watering?
•  Water Stress Can Occur Under 4 conditions’
•  How Applied?
•  When?
•  Soil Drainage (perimeter effect)
Relative Humidity
•  Definition?
•  Optimum?
•  Control?
Temperature (oC)
0
10
20
30
H2O Content (g/m3)
4.9
9.5
17.8
31.8
LIGHT
LIGHT
Major Photoresponses in Plants
1. Photosynthesis
2. Chlorophyll Synthesis
3. Phototropism
4. Photoperiodism
5. Photomorphogenesis
LIGHT
Major Photoresponses in Plants
1. Photosynthesis
2. Chlorophyll Synthesis
3. Phototropism
4. Photoperiodism
5. Photomorphogenesis
& Rate is Temperature Dependent
Photosynthesis
LIGHT
Major Photoresponses in Plants
1. Photosynthesis
2. Chlorophyll Synthesis
3. Phototropism
4. Photoperiodism
5. Photomorphogenesis
LIGHT
Major Photoresponses in Plants
1. Photosynthesis
2. Chlorophyll Synthesis
3. Phototropism
Phototropism is a directional growth response to light, that is a
bending response of plants stimulated by light.
4. Photoperiodism
5. Photomorphogenesis
LIGHT
Major Photoresponses in Plants
1. Photosynthesis
2. Chlorophyll Synthesis
3. Phototropism
4. Photoperiodism
short day, long day, & day neutral plants
5. Photomorphogenesis
LIGHT
Major Photoresponses in Plants
1. Photosynthesis
2. Chlorophyll Synthesis
3. Phototropism
4. Photoperiodism
5. Photomorphogenesis
LIGHT
Major Photoresponses in Plants
1. Photosynthesis
2. Chlorophyll Synthesis
3. Phototropism
4. Photoperiodism
5. Photomorphogenesis
LIGHT
Characteristics?
Intensity
-depends on?
-measured in?
-artificial?
Duration
Quality
LIGHT
Characteristics?
Intensity in the greenhouse
-depends on?
Type of Structure (style & structural components)
Covering Material(s) (type, # of layers, cleanliness, condensation)
Greenhouse Orientation
Latitude
Local Climate & Weather
Time of Year
Shadows
Light
Plant Growth Rate
(Photosynthesis – Respiration)
•  Light Compensation Point (mid Nov to mid February?)
•  Light Saturation Point
TEMPERATURE
& Rate is Temperature Dependent
Photosynthesis
Greenhouse Temperature;
Factors To Consider
Greenhouses heat up for 2 reasons:
1.because of the ‘greenhouse effect’
2. because the greenhouse is an enclosed space
Greenhouse Temperature;
Factors To Consider
The extent to which the temperature of a greenhouse
rises above outdoor temperatures is dependent on :
1.  Amount of solar radiant energy transmitted through
the greenhouse covering
2.  What happens to that energy
3.  How much is retained within the structure
Greenhouse Temperature, As with Light
Intensity, Also Influenced By:
Type of Structure (style & structural components)
Covering Material(s) (type, # of layers, cleanliness, condensation)
Greenhouse Orientation
Latitude
Local Climate & Weather
Time of Year
Shadows
PLUS, OF COURSE, HEAT FROM ANY ARTIFICIAL HEATING SYSTEM
Greenhouse Temperature:
•  Air temperature
•  Leaf Temperature
•  Substrate Temperature
•  Irrigation Water Temperature
Greenhouse Temperature
•  Basic Plant Growth Processes
(Photosynthesis, Respiration, Protein Synthesis & Other Plant Processes)
•  Plant Growth Rate (Photosynthesis – Respiration)
•  Optimum Day/Night Temperatures Combinations
Temperature Affects (minimum, optimum, maximum)
Seed Germination
Vegetative Growth
Flowering (Flower Initiation & Development)
Greenhouse Temperature
Substrate Temperature Affects:
*decomposition of organic matter & availability of nutrients (effect on soil microorganisms; <10C?)
*adsorption of water & nutrients
Factors affecting substrate temperatures:
greenhouse air temperature (lags?).
-how much is influenced by substrate volume (shallow trays/small
pots - larger containers – beds
crop cover
bench type
container (pot) colour
* Substrate temperature and plant diseases
Pythium usually more severe at lower temperatures
Rhizoctonia usually more severe at higher temperatures
Greenhouse Temperature
Temperature of the Irrigation Water:
* irrigation water temperature and substrate temperature differential?
* soilless substrates in containers versus soils in beds?
* crops?
* pathogens?
Temperature
•  Temperature ranges (°C) for seed
germination, growth and development of:
–  cool-season,
–  moderate-season, and
–  warm-season vegetable crops.
Temperature (Celsius)
Cool Season Crops:
–  Beet, Broad Bean, Broccoli, Brussels
Sprouts, Cabbage, Chard, Chives,
Collards, Garlic, Kale, Leek, Onion,
Parsnip, Peas, Radish, Rutabaga, Shallot,
Spinach
•  Seed Germination
–  Min=2; Opt=10-20; Max=35
•  Development
–  Min=4; Opt=13-24; Max=30
Temperature (Celsius)
Moderate-Season Crops:
–  Artichoke, Carrot, Cauliflower, Celery,
Chinese Cabbages, Endive, Lettuce, Lima
Bean, Mustard Greens, Parsley, Potato,
Snap Beans, Sweet Corn
•  Seed Germination
–  Min=4; Opt=13-28; Max=35
•  Development
–  Min=7; Opt=15-26; Max=32
Temperature (Celsius)
Warm-Season Crops:
–  Cucumber, Eggplant, Melons, Okra,
Peppers (sweet and hot), Pumpkin,
Squash, Sweet Potato
•  Seed Germination
–  Min=15; Opt=20-30; Max=40
•  Development
–  Min=15; Opt=18-25; Max=37
Temperature
High & Low temperature injury
High:
Peas : >30C flower abortion
Corn : >34C (poor pollination) plants can survive >45C for short
periods
Low:
Basil +10
Kale -14°C.
CROP CATEGORIES
• 
• 
• 
• 
• 
• 
• 
• 
Baby Leaf Salad Greens
Cool Season Leafy Vegetables
Cool Season Heading Vegetables
Cool Season Root Vegetables
Warm Season Vegetables
Culinary Herbs
Cut Flowers
Small Fruit
QUESTIONS?