QS Study

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.

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