Environmental factors affecting flowering

1. Vernalization

• Vernalization is the cold temperature induction of flowering required in a wide variety of plants
• The necessary degree of coldness and duration of exposure to induce flowering vary from species to species, but required temperature is usually between 0 and 10 °C
• Some plants does not required vernalization treatment such as carrot, radish and leafy vegetables since, they are cultivated for vegetative parts
• Plants like apple, pear and annuals like wheat, barley, oat required vernalization treatment
• Flowering in certain species is affected by a phenomenon called thermal periodicity, in which the degree of flowering is affected by alternating warm and cool temperatures during production
• For eg. Tomato in green house can be manipulated for higher productivity by providing a certain cycle of temperature
• Plants are exposed to high temperature during day time and cold temperature during night time

2. Photo periodism

• Photo period is a phenomenon whereby day length controls certain plant process specially flowering
• According to day length plants are classified as:

a. Short day plant

b. Long day plant

c. Day neutral plant

• Although photo periodism and vernalization both influence flowering , them seem to do so by different mechanism and are not interchangeable
• Plants that needs both treatments will not flower if only one is provided

3. Other factors

• Apart from duration of light, its intensity also affect flowering
• Under the controlled environment of a green house, light is provided in adequate amounts regarding intensity and duration
• When potted flowering plants are purchased for the home, flowering may be poor or lacking because of the low light intensity in most homes
• Flowering has been known to be stimulated under condition of stress from drought
• Excessive moisture during the period of flower initiation causes negative effects in some species