“Colored mulch research can be traced to historic USDA studies dating back to 1918 that led to the discovery of photoperiodism.”

“Cryptochromes are pigmented photoreceptors that are involved in blue-light mediated photomorphogenesis and photoperiodism in plants.”

“The three men formed an informal team to find the substance that controls photoperiodism.”

“In addition to photoperiod and vernalization, ambient growth temperature can have profound effects on flowering.”

“The greenhouse was heated all winter and supplemental lighting extended the photoperiod to prevent dormancy.”

“Exposure of male edible dormice all year round to an unvarying photoperiod and warm temperature disrupted their biological cycles.”

“The photoperiods were lengthened by high-pressure sodium lamps or shortened by black screens when necessary.”

“Calhoun measured responses to varying photoperiods, but tested only one animal in non-normal photoperiods.”

“Researchers collected early and late season eggs, separating some into component parts and incubating others for short or long photoperiods.”