Temperature: usually as temp rises so do metabolisms. Each plant has its temp ranges will encourage stress or prolonged maturation.
Humidity The amount of water in the air. High humidity will prevent plants from transpiring, but can also prevent plants from cooling themselves. High humidity can also create an ideal climate for powdery mildew and botrytis.y the sun, HPS, MH and flu
Evaporation based cooling
Light( Par) Photosynthetic active radiation is the light levels which stimulate photosynthesis. PAR light is produced.
Dissolved O2- Avliable in nutes solution. Roots require O2 to perform respiration. Generally allows between 5-25 ppm of DO in nute for water culture. if DO is not available, anaerobic respiration caused the plant to produce toxic levels of ethanol and plant will drown in its own disease.
Electrical conductivity Higher EC the higher salts in water and matter.