Question

Which of the following is a long day plant?
A. Mirabilis
B. Glycine max
C. Mirabilis jalapa
D. Spinacia oleracea (Spinach)

Answer 1

Hint: Long day plants are those plants which require more sunlight as compared to short-day plants and they grow when the daylight is more than their required photoperiods.

Complete answer:
First of all, you should know what long day plants are. All the plants require sunlight for their growth or for photosynthesis and photoperiodism. When they are exposed to sunlight or darkness, they show different biological responses and reactions and this is called Photoperiodism.
Plants are divided into three main categories depending upon the amount of light or darkness required by the plants:
-Short-day plants
-Long-day plants
-Neutral-day plants.
According to the question, we need to know about long-day plants. These plants grow when the daylight is more than their required photoperiods which is seen in summers.
These plants need more light as compared to short-day plants and they usually flower when the temperature becomes warmer.
Examples of long day plants include spinach, lettuce, radish, sugar beet, etc.
If we look at options now, option A is Mirabilis. It is not a long-day plant but in the question long day plant is asked due to which this option is incorrect and it gets eliminated.
Moving to option B i.e., Glycine max. The common name of Glycine max is Soya bean which is a species of legume and it is widely grown for its edible bean. It is also not a long-day plant but in the question long day plant is asked due to which this option is incorrect and it gets eliminated.
Moving to option C i.e., Mirabilis jalapa. It is commonly known as four o’clock flower and it is available in many ranges of colors. It is also not a long-day plant but in the question long day plant is asked due to which this option is incorrect and it gets eliminated.
Last option D is Spinacia oleracea (Spinach). It is the correct option since it is a long day plant which requires more sunlight as compared to short-day plants.

Thus, the correct answer is option D i.e., Spinacia oleracea (Spinach).

Note: From all the given options, Mirabilis, Glycine max, Mirabilis jalapa are not long day plants but spinach is a long day plant which requires more sunlight than short days due to which that becomes the correct option.