Definition of photoregulation in US English:
photoregulation
noun
Biology
The regulation of a biological or chemical process by means of the intensity, duration, etc., of light.
Origin
1960s; earliest use found in Science. From photo- + regulation [adjective], after photoregulate.
Pronunciation
photoregulation
/ˌfəʊtə(ʊ)ˌrɛɡjʊˈleɪʃn/