Core terms

Alkalinity

Water’s acid-neutralizing capacity; it is not the same thing as pH.

Anthesis

The period when a flower is functionally open; in male cannabis this includes pollen-shedding stages.

CEC

Cation exchange capacity: the ability of a material to hold and exchange positively charged ions.

Chemotype

A chemically characterized biological type, commonly used when discussing cannabinoid or other metabolite profiles.

Clone

A plant propagated vegetatively from donor tissue and expected to share the donor genotype, subject to mutation, disease, and handling effects.

DLI

Daily light integral: the total photosynthetically active photon exposure received per square meter per day.

Dryback

A defined decline in substrate water content or weight between irrigation events; the measurement method must be stated.

EC

Electrical conductivity: a measure related to dissolved ionic concentration, commonly reported in mS/cm or µS/cm.

Genotype

The genetic constitution of an organism or the alleles considered at specified loci.

Hardness

Primarily the concentration of dissolved calcium and magnesium ions in water; distinct from alkalinity.

IPM

Integrated pest management: prevention, monitoring, identification, thresholds, lawful controls, and evaluation used as a coordinated system.

PAR

Photosynthetically active radiation, conventionally the 400–700 nm photon waveband used in plant-light measurement.

Phenotype

Observable traits produced by the interaction of genotype, development, and environment.

Photoperiod

The duration and timing of light and dark within a 24-hour cycle.

pH

A logarithmic measure related to hydrogen-ion activity; it does not directly measure alkalinity or nutrient concentration.

PPFD

Photosynthetic photon flux density: PAR photons arriving at a surface per square meter per second, usually µmol·m⁻²·s⁻¹.

Rhizosphere

The soil or substrate region directly influenced by roots and associated organisms.

Runoff

Drainage leaving a container after irrigation; interpretation depends on system, sampling, timing, and method.

Senescence

Regulated aging and remobilization processes that precede tissue death.

VPD

Vapor pressure deficit: the difference between saturation vapor pressure and actual vapor pressure; plant interpretation depends on leaf and air conditions.