OIC what you are getting at, the dark period vs light period isn't about running photosynthesis in the dark. The length of the night controls hormonal output that controls the growth of the plant and it's seasonal growing, flowering and fruiting.
My idea that is if the dark length controls these factors, ( I am shooting for 24 hours of day and 12 hours of night) slowly decreasing the length of night should trigger the growth cycle independent of the day length.
At least that is my speculation.