Photoperiodism In Plants
• Response of plant to day light period specially flowering behaviour is called photoperiodism.
• The term photoperiodism was coined by Garner and Allard (1920). They classified plants into three categories:
a. Short day plants:
• Such plants require the day length less than 12 hours for flower initiation.
• E.g. tobacco, soybean, rice, generally kharif crops and many tropical plants.
b. Long day plants:
• Such plants require more than 14 hours day light for flower initiation.
• E.g. wheat, barley, sugar beet, castor, generally Rabi crops
c. Day neutral plants:
• Such plants are unaffected by the day length e.g. maize, tomato, buckwheat, sunflower, cotton, cucumber etc.