- CFL: Acronym for "compact fluorescent”.
- Chlorosis: The yellowing or whitening of normally green plant tissue because of a decreased amount of chlorophyll.
- CO2: Chemical symbol for “carbon dioxide”.
- Conductivity: See EC.
- EC: Acronym for "electrical conductivity".
- Ground water: Under-ground water deposit e.g. artesian bore.
- Hardness (or “hard”).
- HID: Acronym for "high intensity discharge" lamp.
- HPS: Acronym for "high pressure sodium" lamp.
- Make-up water: Water used during the process of making a fresh batch of nutrient solution.
- MH: Acronym for "metal halide" lamp.
- Mottling: Spots or blotches of different shades or colors commonly found on leaves.
- mS: Short-hand representation of "mS/cm".
- Natural water: Water supply that is uncontaminated by pollution.
- Necrosis: Death of plant cells resulting in dead/brown spots on foliage (Fig 15.1).
- NFT: Acronym for "nutrient film technique".
- Nutrient solution: The diluted nutrient that is fed to plants. It is usually comprised of a nutrient concentrate, water and nutrient additives. For the purpose of clarity, the nutrient solution is sometimes referred to as the "working nutrient solution".
- O2: Chemical symbol for “oxygen”.
- Oxidizing agents: For the purpose of this book, this term is used to describe substances which attack organic material such as bacteria and viruses.
- pH.
- PGR: Acronym for "plant growth regulator".
- ppm: Acronym for "parts per million”. “ppm” has the same meaning or numerical value as “mg/L”.
- Precipitate (or “precipitation”): Insoluble solid deposit that forms within a nutrient solution or water which eventually sinks to bottom of reservoir or adheres to sidewalls.
- Recirculating nutrient (or “recirculating system”): The process (or system) where the working nutrient solution is recirculated.
- Respiration (or “respire”).
- RH: Acronym for "relative humidity".
- RO: Acronym for "reverse osmosis".
- Run-to-waste: Type of growing system or method.
- Saline (or “salinity” / “salty”): A water that contains excessive salt levels - usually sodium chloride.
- Scheme water: Water supply provided by a local authority.
- Surface water: Above-ground water deposit e.g. river, stream, lake, dam, soak.
- TDS: Acronym for "total dissolved salts".
- Top-up water: Extra water added to a nutrient solution to increase the dilution factor or maintain a desired level.
- Transpiration (or “transpire”)
- Wilt (or “wilting”): The drying out, drooping, and withering of the leaves of a plant due to inadequate water supply, excessive transpiration, or vascular disease.
- Working nutrient solution: See "nutrient solution".
BACKGROUND INFORMATION: Hydroponic System Checklist