Question

Which one is a long day plant?

• A. Tobacco
• B. Glycine max
• C. Mirabilis jalapa
• D. Spinach

Answer 1

The correct option is D Spinach

Flowering in certain plants depends not only on a combination of light and dark exposures but also their relative duration.
All plants need sunlight for their growth or photosynthesis or photoperiodism. Plants show specific biological responses and reactions when they exposed to a specific period of sunlight and darkness. This phenomenon is called as photoperiodism. Depending on the amount of light or darkness required for survival and development, plants are divided into three main categories: Short-day plants, long-day plants, and neutral-day plants.
Long-day plants flower and grow when the daylight they obtain is more than their critical (required) photoperiod, like in summer season. They need more light than short-day plants and usually flower when the temperature becomes warmer. Examples of long day plants are spinach, lettuce, radish, sugar beet, etc. Thus, the correct answer is Spinacia oleracea (spinach).