8.Protected environments Flashcards
1
Q
Name key types of protected environments
A
- Greenhouse (Glasshouse) - Freestanding, made of glass
- Conservatory = Made of glass, attached to building
- Cold frame = Mini greenhouse with openable lid
- Polyethylene tunnel = plastic stretched over metal hoops
- Cloche = Small and portable, can be glass or plastic
2
Q
Uses for a protected environment
A
- Plants from warm climates can be grown in colder ones
- Plans can be grown earlier or later in the season
- Crops can be produced out of season
- Propagation is in a controlled environment
- Overwinter tender plants
- Plants grown for education/study/conservation
- Commercially to grow decorative plants for sale
3
Q
Pro’s/con’s of Protected environments
A
- Higher temperature day and night = faster growth for longer
- Gas composition can be controlled (in certain structures)
- Higher humidity than outdoors
- Light levels may be controlled
- Protection from wind/wind chill
- Irrigation needed as no rain - dryer on hot days
- Air movement reduced
- Light levels may be reduced
- Pest and disease which may not occur externally can easily spread - humidity/space
- Optimum growth req different for different plants
4
Q
Pro’s/con’s of using a Greenhouse
A
- Physically robust
- Effectively permanent structure
- Ease of access
- Glass can be broken
- Expensive to build /maintain older units
5
Q
Pro’s/con’s of using a Polytunnel
A
- Can be moved easily
- Cheap
- Ideal for crops which need minimal protection
- Easily damaged
- Access can be hard if low to ground
- Low insulating properties
- Hard to ventilate
6
Q
Lycopersicon esculentum
Why grow in a Greenhouse
A
- Plants may be started early from seed whilst protected from frost
- Warmer night temp encourages faster growth
- Warmer temp enabled faster ripening
- Plant protected from rain
- Can continue to grow/fruit later into the autumn
- Biological control of pests can be used
- Co2 can be controlled to boost growth (commercial)
7
Q
Key materials for use on Protected environment
A
Supporting framework to hold structure
- Aluminum (metal conducts electricity)
- Softwood (High maintenance)
- Cedarwood (Hardwearing/long-lasting)
Cladding material - lets in light and retains heat
- Glass
- Polycarbonate
- PVC
- Polyethylene
- Acrylic (flexi/perspex)
8
Q
Pro’s/con’s of using a Glass cladding
A
- Good light transmition (up to 97%)
- Heavy - requires specialist handling
- Poor thermal efficiency
9
Q
Pro’s/con’s of using a Polyethylene cladding
A
- Very light - easy to use
- Cheap
- Flexible
- Will eventually degrade in sunlight
- Very poor thermal efficiency
10
Q
Pro’s/con’s of using a PVC cladding
A
- Very light - easy to use
- Cheap
- Flexible
- Stronger/longer lasting than Polyethylene
- Will eventually degrade in sunlight
- Very poor thermal efficiency
11
Q
Pro’s/con’s of using a Acrylic cladding
A
- Easy to cut to shape
- Cheap
- Scratches easily
- Gets dirty with age
12
Q
Pro’s/con’s of using a Polycarbonate cladding
A
- Lightweight and strong
- Easily cut to shape
- Twin walled has high insulating properties
- Expensive
13
Q
Natural Light levels within protected environment will depend on:
A
- Aspect - facing sun or not
- Shading from tree’s/buildings
- Orientation
- Cladding material
- Shape of structure - light able to enter or reflect
14
Q
How are protected environments Heated
A
- Passive heating - Structure traps solar radiation
- Oil or gas fired central boiler with wet piped system
- Portable heaters with bottled gas
- Electric heaters
- Costs vary greatly
15
Q
How is ventilation controlled in protected environments
A
- Manual windows - asides and roof (apex) - Warm air rises through roof and cold air sucked in through side windows
- Motored windows
- Electric fans - produce air movement
- Netted sides
16
Q
How is Shading controlled in protected environments
A
- Key in summer
- Blinds - external more effective (Manual/electric)
- Netting
- Shade paint - outer side of glazing
17
Q
How is Cooling controlled in protected environments
A
- Add shade
- Ventilation
- Water - cools surface it evaporates from
- Floors can be ‘damped down’ / increase humidity
18
Q
How is Irrigation controlled in protected environments
A
- Watering can/spray lance - can be directed at plants that need it most
- Capillary reservoir - draws water to base of container plants where it can be absorbed into the soil - best to plants that need constant moisture
- Automated system - valves deliver water at pre-set time intervals, drip irrigation most effective
19
Q
Artificial Lighting options for protected environments
A
- Key in dark winter months
- Must be photosynthetically active radiation (PAR)
- Florescent tubes - common, compact
- High pressure sodium (HPS) - expensive (also provide heat)
- LED - increasingly popular
20
Q
Pest and disease control in protected environments
A
- Major problem due to rate of spread
- Chemical controls increasing un-acceptable - only used as last resort
- Integrated pest management system (IPM)
- Prevention - Appropriate temp, ventilation, humidity, hygiene, resistant cultivar
- Monitoring - Look for signs of problems/ immediate action
- Biological - Predator/parasite introduced
21
Q
Advantages and disadvantages of IPM
A
- Less pest resistance to chemicals
- Safer for humans and animals
- No/little environmental impact
- Pest needs to be established for bio control to work
- Can be expensive
- Workforce needs specific training
22
Q
Considerations for plants in containers in a protected environment
A
- Easily moved in/out
- Can be grown in specific soil
- Need regular watering/feeding
- Can overheat in high temp
- Terracotta = Widely used, porous, heavy, dries out quick
- Synthetic/Plastic = Light weight, cheap, don’t age well
- Reconstituted stone = Permanent, not moveable, expensive
- Compressed material = Short lives, can biodegrade and become food for plant
23
Q
How is Irrigation controlled in Indoor environments
A
- Crucial for survival
- Self watering pots reduce the need for manual watering
- Most plants do best if watered just as soil begins to dry out
- Excessive watering can cause severe problems
- Standing on saucers or gravel helps minimise damage
24
Q
How is Light controlled in Indoor environments
A
- Light is the major limiting factor
- Most need good, bright, diffused light with direct on part of the day
- Succulent/cacti need sun all day
25
Q
How is Humidity controlled in Indoor environments
A
- Usually lower levels indoors than required
- Daily misting can help increase - key for tropical plants
- Gathering plants together to create micro climate
- Standing on gravel/tray where water can evaporate from
26
Q
How is Temperature controlled in Indoor environments
A
- May fluctuate due to heating - this can damage plants
- Drafts should be avoided
27
Q
Routine care of plant in Indoor environments
A
- Dead/damaged material removed
- Inspect for pest/disease (cure with bio control if possible)
- Dusting leaves to enable photosynthesis
- Vigorous plants need feeding often - Liquid or slow release
- Potassium rich or specific indoor plant food most suitable
28
Q
Considerations for plants in containers in Indoor environment
A
- Must have holes for drainage with saucer or tray
- Sterile pot plant compost is suitable - must have good drainage
- Re-pot as necessary - large pot, large plant
29
Q
Common pests/disease of Indoor plants
A
- Aphids, whitefly, scale, mealy bug
- Treat with fatty acid sprays for small collections
- Bio control for larger infestations
- Fungal problems occur as a result of overwatering. low humidity or poor ventilation
30
Q
Label greenhouse diagram
A
- Ridge
- Ridge ventilator
- Internal framework
- Gutter
- Louvered ventilator
- Cladding of structure
