All plants require light to grow and develop, though some plants don’t require as much light as others. In this lesson, we’ll examine a group of plants known as short-day plants.
In order for plants to grow and thrive, they must have a certain amount of sunlight. Sunlight is important for the processes of photosynthesis and photoperiodism. Photoperiodism is the physical reactions and developmental responses of plants to the amount of sunlight they receive. The amount of light a particular plant requires more or less of is known as its critical photoperiod.
Botanists divide plants into three main categories based on how much light or darkness they need to survive and thrive: short-day plants, long-day plants, and neutral-day plants. Although these terms refer to the day or sunlight a plant needs, scientists now know that it’s actually the amount of darkness a plant experiences that determines how it will grow, and in the case of flowering plants, when it will bloom.Short-day plants flower when the day length is less than the plant’s critical photoperiod, which usually happens in the fall when daylight lasts less than 12 hours or so. They are unable to flower during long days with extreme amounts of sunlight or when exposed to a great deal of artificial light. These plants require regular periods of darkness to mature and flower, and they typically begin their growth during the summer months but do not flower until fall, when the days are getting shorter.
There are many varieties of short-day plants that grow all over the world. Two of the most well-known flowering plants are chrysanthemums, which includes alecosts, marguerites, some species of daisy, and poinsettias, which are commonly used as Christmas flowers.
Chrysanthemums typically have a critical photoperiod of about 15 hours, meaning they need less than 15 hours of daylight to bloom, while poinsettias have a critical photoperiod of about 10 hours, meaning they need less than 10 hours of light to flower. In addition to these popular flowers, many short-day plants are important to agriculture such as cotton, rice, and sugar cane.Cotton is used in the creation of many different products. It is planted in the spring of the year but doesn’t bloom until late fall.
Rice is a staple food for much of the world’s population and is grown in water-filled paddies during the spring and summer months; however, it can’t flower and produce its grains until the days become shorter, and it receives less light. Sugar cane is the world’s largest crop. Farmers extract the sugar and use the remaining parts of the plant for animal food. Sugar cane thrives in late summer and fall, when the days are much shorter .
Short-day plants are found all over the world and are defined as those plants that flower when the day length is less than the plant’s critical photoperiod, which usually happens in the fall when daylight lasts less than 12 hours or so.
A critical photoperiod refers to the amount of light a particular plant requires more or less of, and the term photoperiodism refers to the physical reactions and developmental responses of plants to the amount of sunlight they receive. Short-day plants ultimately thrive in conditions with low amounts of light, that is, when the nights are longer. Thus, short-day plants do best in the late summer and fall months, when there is less daylight to interfere with their growth. Common examples of short-day plants include chrysanthemums and poinsettia flowers, cotton, rice, and sugar cane.