Influence of Length of Daytime on Flowering of Plants

The influence of length of daytime on flowering of plants is called Photoperiodism.

In 1920 Garner and Allard observed the affect of photoperiods in Maryland Mammoth a variety of tobacco plant. According to effect of length of day and night (photoperiods) upon the flowering time Gamer and Allard classified the flowering of plants into three classes:

  • Short day Plant: These plants flowers when day length is short. Dahlia, Tobacco, Chrysanthemum are short-day plants. They may also call long-night plants. Two species of jute are short-day plants. In 10 – 12 hours photoperiods plants flower in 30 days. More than 1212 hours of photoperiods delayed flowering.
  • Long day Plant: These plants give flower when thy-length is longer. Sponge guard (Luffa) Lettuce and Beta palonga (Palong) is long day plants. They may also call short night plants.
  • Day-Neutral Plants: Flowering time of these plants does not depend on the duration of daylight. They flower when necessary vegetative growth is completed. Day-neutral plant can be grown in both winter and summer. They flower in both the seasons. Sunflower is a plant of this type. Aus paddy usually a day-neutral plant.

Leaves receive the stimulation of photoperiods.