NFT (Nutrient Film Technique) (See growing technique in the grow room): Uses a thin film of nutrient concentrated water to grow plants sitting in a growing media. Clean, easy, consistent.

VPD (Vapour Pressure Deficit): is the difference (deficit) between the amount of moisture in the air and how much moisture the air can hold when it is saturated. Once air becomes saturated, water will condense out to form clouds, dew or films of water over leaves.

Irrigation (Irri): watering of plants
Fertigation: The process of putting nutrients (fertiliser) into the irrigation system. Makes use of the current infrastructure to irrigate (pipes, sprinklers, drippers, pumps). Easy to manage and monitor accurately.
Photosynthesis: Process in which a plant makes carbohydrate (energy/food/sugar) Sun + Water + Co2 = Carbohydrate + Oxygen. Occurs during the day with sunlight or when sunlight is substituted with an artificial light source
Respiration: Plant respiration is the opposite of photosynthesis, which is a biological process performed by green plants that creates oxygen and releases it into the air. During respiration, plants absorb free molecules of oxygen (O2) and use them to create water, carbon dioxide, and energy, which helps the plant grow.
PAR (Photosynthetically Active Radiation): This is the spectrum of solar radiation (400-700nm) which organisms that can photosynthesise such as plants, algae etc. use for photosynthesis. This is measured in nanomols (nm)
EC (Electrical Conductivity): Measure of the salts (Nutrients) in the irrigation solution. Example is lettuce having the EC around 0.8-1.2, Tomatoes anywhere from 2-5. Most crops will have a range and the specific grower will have his own thoughts on what works for him/her and use their experience to have a suitable target. Same for pH.
TDS (Total Dissolved Solids): Another measure of Nutrient in the irrigation solution. EC is more common measurement.
Ppm (parts per million): This is a measure of concentration of a substance in solution.
pH: Measures the acidity or alkalinity of the irrigation solution. This affects the availability of nutrient. As the plant grows it takes up nutrient which means the pH becomes more acidic or basic depending on what nutrient is taken up e.g. if the plant takes up one of the positive nutrients (Calcium, Potassium, Magnesium) they are replaced by an acidic ion (Hydrogen) from the root system so the solution becomes more acidic. This is the same for the plant taking up negative nutrients (Nitrogen) and being replaced by a hydroxide ion creating a more alkaline solution. If this is not kept in check by monitoring pH you will either have too higher pH or too lower pH meaning there will be some valuable nutrients locked away from the plant (see figure 2). Plants will only grow as fast as the most limiting nutrient so you will want to understand what nutrients are critical for each plant and keep the pH in the appropriate range.
Peri Pump (Peristaltic Pump): Small pumps used to dose nutrient or a pH increase/decrease solution into a reservoir of a hydroponic system.

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