Physiological of Flowering

Physiology of Flowering

  • Flowering is a critical reproductive process in plants. 
  •  Regulated by internal and external factors.

 

Photoperiodism:

  • Plants detect changes in day length. 
  • Response varies among species:

- Long-day, short-day, or day-neutral plants. 

  • Perception primarily in leaves. 
  • Involves complex hormonal signaling. 
  • Triggers transition to flowering.

 

Vernalisation:

  • Exposure to cold temperatures induces flowering. 
  • Prevents premature flowering. 
  • Molecular mechanisms involve gene expression changes. 
  • Critical for plants in temperate climates. 
  • Ensures optimal timing for reproduction.

 

Significance:

  • Essential for successful reproduction. 
  • Insights into plant adaptation. 
  • Implications for agriculture and horticulture.

 

Photoperiodism

  • Photoperiodism is the phenomenon where plants exhibit different responses to the duration of light and dark periods in their environment. 
  • It refers to the ability of plants to measure the length of day and night and use this information to regulate various physiological processes, particularly flowering. 
  • Plants exhibit different flowering responses based on the duration of light exposure relative to the critical duration required for flowering induction. 
  • Some plants require periodic exposure to light to initiate flowering. 
  • Certain plants measure the duration of light exposure, influencing their flowering response. 
  • Plants fall into three categories based on their response to light duration: long day plants, short day plants, and day-neutral plants. 
  • The critical duration of light exposure varies among different plant species.

 

Types of Plants:

  • Long Day Plants: Require a light period longer than a critical duration to induce flowering. 
  • Short Day Plants: Flower when exposed to light for a duration shorter than the critical period. 
  • Day-Neutral Plants: Flower independently of light duration.

 

Significance of Light and Dark Periods:

  • Flowering response not only depends on the duration of light exposure but also on the duration of darkness. 
  • The relative durations of light and dark periods play a crucial role in photoperiodism.

 

Site of Perception:

  • While shoot apices transform into flowering apices, they cannot perceive photoperiods on their own. 
  • Leaves are the sites where light/dark duration is perceived.

 

Role of Hormones:

  • Hypothesized that hormonal substances from leaves induce flowering in shoot apices only under specific photoperiods. 
  • Hormonal migration from leaves to shoot apices triggers the flowering response when exposed to the appropriate photoperiod.

  

 

 

Vernalisation

  • Vernalisation refers to the process where flowering in plants is influenced by exposure to low temperatures for a specific duration. 
  • It is crucial for preventing premature flowering late in the growing season, allowing plants to reach maturity. 
  • Promotion of Flowering: Vernalisation specifically promotes flowering in response to a period of low temperature. 
  • Varieties: Some plants, like wheat, barley, and rye, have winter and spring varieties. Winter varieties require vernalisation to flower properly, while spring varieties do not. 
  • Winter Varieties: Planted in autumn, winter varieties germinate and undergo vernalisation during the cold season. They resume growth in spring and are harvested in mid-summer. 
  • Biennial Plants: Certain biennial plants, such as sugarbeet, cabbages, and carrots, require vernalisation to induce flowering in their second season.
  • Exposing biennial plants to cold treatment stimulates a subsequent flowering response, often in conjunction with photoperiodic cues.