Table 2.
Primary parameters
| What to measure | Units | Where to measure | When to measure | What to report |
|---|---|---|---|---|
| (a) Minimum set | ||||
| Air temperaturea | oC | At canopy level, in centre of growing area. Location of sensor is crucial and should be independent of the greenhouse temperature control sensor. Include another sensor for outside temperature | Preferably continuous, but at least hourly | Mean and standard deviation for light and dark periods. Number of locations (preferably more than one) |
| Substrate temperature | oC | Centre of root matrix for solid and liquid substrates | As above | As above |
| Radiation (PARa) | µmol m−2 s−1 | At top of canopy, in centre of growing area | Preferably continuous but at least hourly | Mean and standard deviation. Number of measurement locations (preferably more than one). When used, supplementary radiation sources (type, model and manufacturer, distribution, energy consumption, conversion efficiency), and their duration of operation |
| Photoperiod | h | – | Daily or when conditions change | Duration of light period (including any night interruption) |
| Atmospheric moisture: relative humidity or vapour pressure deficit (VPD) | % or kPa | At canopy level, in centre of growing area and independently of the greenhouse humidity control sensor | Preferably continuous but at least hourly | Mean and standard deviation for light and dark periods. Number of locations (preferably more than one) |
| Atmospheric CO2 concentrationb | µmol mol−1 | At canopy level, at a representative location | Preferably continuous but at least hourly if CO2 enrichment is used | Mean and standard deviation/Number of measurement points and their location relative to the plant canopy |
| pH | – | In root zone environment, or in nutrient solution directly applied to the root zone environment | Preferably continuous, but at least hourly | Mean and standard deviation, Location of measurement(s) |
| Electrical conductivity (EC) | S m−1 | In root zone environment, or in nutrient solution directly applied to the root zone environment | Preferably continuous, but at least hourly | Mean and standard deviation, Location of measurement(s) |
| Nutrient—liquid media | mmol L−1 | – | Daily or when replenished | Ionic concentration in added solution. Frequency of additions. Aeration if any |
| Nutrient—solid media | mol kg−1 (dry) | – | When added or replenished | Nutrients and their form added to soil media. Frequency of additions |
| Watering | Litre (L) | Growing system | At start of experiment and when changed | Frequency, amount, duration and type of water added per unit area or per plant. Mean and standard deviation. Type of irrigation system |
| Plant alignment | – | On bench/floor/hanging system | At start of experiment and when conditions change | Number of plants per unit area and number of re-spacings or relocations |
| Greenhouse properties | Greenhouse | At start of experiment | Latitude and longitude. Orientation of long axis relative to compass North. Size (floor area m2, growing area m2, gutter height m, peak height m), type (free standing, gutter connected), shape (curved roof, peaked roof). Manufacturer and model if available, indicate if it has special features (e.g. type of glazing material, energy/shade curtain) | |
| (b) Additional parameters | ||||
| Surface temperature b | oC | Plant tissue: pointed at canopy or individual leaf surface. Greenhouse: pointed at structural surface | Preferably continuous, but at least hourly | Mean and standard deviation. Location and orientation of the sensor. Distance of the sensor to the surface measured. Field of view of the sensor |
| Radiation (net) | W m−2 | At top of canopy, in centre of growing area | As above | Mean and standard deviation. If measured, also report solar radiation so that (net) long wave radiation can be determined |
| Radiation (spectral) | µmol m−2 s−1
nm−1 |
As above and/or where of interest (e.g. within the canopy) | As often as practical | Mean and standard deviation. Absolute or relative contribution of a specific wavelength or waveband to the overall radiation |
| Irradiance (solar) W m−2 |
W m−2 | Outside (unobstructed) and/or inside (at top of canopy, in centre of growing area) | Preferably continuous, but at least hourly | Mean and standard deviation. When possible, calculate (average) transmission of radiation through the greenhouse cover |
| Radiation (integral) | MJ m−2 d−1 or mol m−2 d−1 | Calculated from accumulated data | Continuously during the measurement interval | Accumulated (typically daily) values. Relative contributions of supplementary and solar radiation to (daily) integral |
| Air circulation | m s−1 | At canopy level | At start of experiment and more frequently if conditions change | Mean and standard deviation Design of circulation system. Predominant direction of flow. Number of measurement points and their location relative to the plant canopy. Report whether open or closed greenhouse |
| Substrate water content: volumetric or gravimetric water content, or matric potential | % or kPa | Substrate | Daily | Mean and standard deviation. Number of measurement locations |
| Dissolved oxygen | mg L−1 | In root zone environment, or in nutrient solution directly applied to the root zone environment | Preferably continuous, but at least hourly | Mean and standard deviation. Location of measurement(s) |
aReferred to as photosynthetically active radiation (PAR: 400–700 nm) for general usage and described as photosynthetic photon flux density (PPFD) by many journals, professional societies and manufacturers of quantum sensors.
bReport if records are available, and always when it is a variable under investigation.