RHS Level 2 R2114 Protected Environments Flashcards
Understanding protected environments and their use
Describe a range of protected structures.
Greenhouses - aluminium or wood frame, glass or plastic windows. Traditional span, Dutch light, dome shaped, lean to.
Cold frame - usually bricks with a transparent lid
Polytunnels - steel frame, covered in polythene, range of sizes
Cloches - low polythene structure, enviromesh over hoops, glass cloches.
Conservatories - wood, uPVC, against a wall.
Describe the horticultural uses for different protected structures.
Greenhouse and polytunnels - plant propagation, cuttings, seed sowing, growing on tender seedlings., growing fruit, salad, vegetables and herbs, main season cropping
Cold frame - hardening off, starting off some veg.
Conservatories - specialist plant collections, displaying tender perennials and houseplants
Cloches - growing fruit, salad, vegetables and herbs, main season cropping
What are the factors affecting plant growth which are changed by protected environments?
Light Carbon dioxide Temperature Air movement Relative humidity Pests and diseases
How is light changed by protected environments?
Structures reduce the amount of light reaching the plants with shading, reflection, and the amount transmitted.
Quality of light is altered, proportions of different wavelengths are changed.
These influence the rate of photosynthesis.
Sunlight entering a structure will also affect temperature.
How is carbon dioxide changed by protected environments?
Level of CO2 in a closed environment will often drop below that of the outside during the day.
This will reduce the rate of photosynthesis.
CO2 is also affected by air movement.
How is temperature changed by protected environments?
Temperature increases in protective structures due to change in sunlight.
During colder times of the year the temperature improvement has a considerable effect on plant growth.
How is air movement changed by protected environments?
With little air exchange with the outside, CO2 levels can become depleted, reducing the rate of photosynthesis.
Humidity will increase and as a result cooling by transpiration is reduced and leaf temperatures can increase.
Plants inside are subject to less turbulent conditions.
How is relative humidity changed by protected environments?
Humidity often increases in a closed structure.
This reduces transpiration, which reduces water stress.
Too little transpiration can mean there is no cooling effect in very hot conditions and uptake of nutrients may be affected.
High humidity may also increase some fungal diseases.
How are pests and diseases changed by protected environments?
Warmth and humidity can increase pests (reproduction rates increases) and diseases (fungal diseases spread faster).
The structure itself may exclude the arrival of spores or pests.
