A Long-Day Plant Will Flower

Question

A long-day plant will flower
A) in the late fall.
B) when the night is shorter than a critical value.
C) only under artificial light in the summer.
D) during short days with proper fertilization.
E) regardless of the photoperiod imposed.

Accepted Answer

Long-day plants require a minimum critical period of darkness to flower, and any night length below that threshold will induce flowering. Therefore, option B is the correct choice. Option A is incorrect because long-day plants typically flower in the late spring or summer, not in the late fall. Option C is incorrect because long-day plants require natural light to flower, not artificial light. Option D is incorrect because long-day plants require long nights, not short nights, to flower. Option E is incorrect because long-day plants are photoperiodic, meaning their flowering is influenced by day-length.