| The photoperiods were lengthened by high-pressure sodium lamps or shortened by black screens when necessary. |
| However, potatoes grown in the major production areas in Europe, North America and Asia must be able to tuberize under the long photoperiods of temperate zone summers. |
| Plasma prolactin and gonadotrophins during gonadal development and the onset of photorefractoriness in male and female starlings on artificial photoperiods. |
| Researchers collected early and late season eggs, separating some into component parts and incubating others for short or long photoperiods. |
| Calhoun measured responses to varying photoperiods, but tested only one animal in non-normal photoperiods. |
| Effect of natural and artificial photoperiods and fluctuating temperature on age of first mating and mating frequency in the navel orangeworm, Amyelois transitella. |
