Question

Plant hormones can be used by farmers to manage plant growth. Give two examples of the commercial value of plant hormones.

Answer 1

• Phytohormones are chemicals just like animal hormones that help in the growth, development and functioning of plants.
  
• There are five major phytohormones - auxin, cytokinins, gibberellins, abscisic acid and ethylene. Each hormone differs in its effects.
• The auxins, gibberellins and cytokinins act as growth stimulators, whereas, abscisic acid and ethylene act as growth inhibitors.
  
• The application of auxin to cut shoots causes growth of new roots. If this is then planted either hydroponically or in an orthodox compost planter and the plant can thus be cloned.
  
• Synthetic auxins can be sprayed onto unwanted plants, causing an increase in metabolism and this results in rapid plant growth. This soon becomes unsustainable and the plant dies.
• Many farmers use ethylene to artificially ripen fruits like papaya, mango, etc.