Growth and Development of Horticultural Crops (1+1)

Distribution of gibberellins in plants

• Gibberellins are found in all parts of higher including shoots, roots, leaves, flower, petals, anthers and seeds.
  
• Gibberellins activity has also been shown in plastids.
  
• In general, reproductive parts contain much higher concentrations of gibberellins than the vegetative parts.
  
• In growing embryos after fertilization, cell division takes place vigorously, aided by auxin followed by cell expansion. Gibberellins are responsible for cell wall loosening and cell enlargement.
• These enlarged cells import assimilates from the source for storage in the reproductive organs.
  
• Hence, gibberellins play major role in increasing yields of seeds and fruits.
  
• Immature seeds are especially rich in gibberellins (10-100 mg per g fresh weight) and are most favorite plant parts for isolation of gibberellins and their study.
  
• In mature seeds, the gibberellins tend to form their derivatives.
  
• In plant, the gibberellins may occur in two different forms- free gibberellins and bound gibberellins.
  
• Bound gibberellins usually occur as gibberellins-glycosides.