One species of plant produces flowers when nights are 10 hours long. a related species comes into flower when nights are 9 hours long. what type of reproductive isolation would include this example?

Temporal isolation is the type of reproductive isolation that would include this example.

Temporal isolation is a type of reproductive barrier in which two closely related species (plants or animals) are prevented from mating and producing sterile hybrids because of their different breeding time. The difference in the breeding time may be year, season (such as fall or winter) or by time of day (daytime or at night).