Iris is a long-day plant that normally flowers in the spring. Which of the following regimens would be the most effective in making an iris bloom in late fall?
A)interrupting the plant's nights at 2:00 am with a flash of far-red light
B)interrupting the plant's nights at 2:00 am with a flash of red light followed by a flash of far-red light
C)interrupting the plant's nights at 2:00 am with a red flash, then a far-red flash, then a red flash
D)interrupting the plant's days at 2:00 pm by putting it in the dark

Question

Quizplus · Accepted Answer

Interrupting the plant's nights with a red flash, then a far-red flash, then a red flash effectively simulates longer daylight conditions, promoting flowering in long-day plants like iris.

Iris Is a Long-Day Plant That Normally Flowers in the Spring