PGR part 1

• a natural substance produced by plants that acts to control plant activities; chemical messengers


  Plant hormones
• Include plant hormones (natural and synthetic), but also include non-nutrient chemicals not found naturally in plants that when applied to plants, influence their growth and development.


  Plant growth regulators
• What are the 5 recognized groups of natural plant hormones and growth regulators?

  Auxins, Gibberellins, Cytokinins, Ethylene, and Abscisic acid
• Classification of chemical messengers

  Hormones and vitamins
• The site of synthesis is different from the site of action

  Hormones
• These are chemical messengers that are physiologically active

  Plant hormones
• A chemical messenger used in the same part without being transported

  vitamins
• A chemical messenger; by themselves are not physiologically active; act as a co-factor or enzyme

  Vitamin
• Greek root word Hormone is derived from


  Hormao
• What does hormao mean?


  to stimulate
• Who coined the term hormone?

  Beylis and Starling (1902)
• Suggested using the term Phytohormone for hormones of plant


  Thimann (1948)
• are organic substances produced naturally by the plants which in minute/low concentration; modify plant growth and development

  Phytohormone
• refers to natural or synthetic substances that influence plant growth and development

  Plant growth regulators
• All plant hormone are plant growth regulators but all plant growth regulators are not plant hormones