demonstrations:asexual_reproduction_of_onion

Asexual Reproduction of Onion

Materials: ★☆☆ Easy to get from supermarket or hardware store
Difficulty: ★☆☆ Can be easily done by most teenagers
Safety: ★☆☆ Minimal safety procedures required

Categories: Plants, Reproduction

Alternative titles: Growing an Onion in Water

Summary

An onion is suspended over a jar of water to observe root and shoot growth through vegetative reproduction.

Procedure

  1. Take a healthy onion bulb.
  2. Insert several toothpicks around its middle so that it can rest securely on the rim of a jar.
  3. Fill the jar with water until the base of the onion just touches the water surface.
  4. Place the setup in a dark cupboard or shaded area.
  5. Over the next few weeks, observe the base of the onion for new root growth and the top for sprouting shoots.
  6. Record or photograph any visible changes in growth.
  7. After several weeks, describe the appearance of the roots and shoots and identify the method of reproduction taking place.

Growing Onions - Experiment - Huw Richards:


Variations

  • Repeat the same setup using a clove of garlic or a piece of potato.
  • Try placing the onion in different lighting conditions to see how light affects growth.
  • Compare results between onions with and without the outer dry layers removed.

Safety Precautions

  • Handle toothpicks carefully to avoid injury.
  • Use clean jars and change the water regularly to prevent mold or odor.
  • Wash hands after handling plant materials.

Questions to Consider

  • What type of reproduction is taking place in this demonstration? (Vegetative or asexual reproduction.)
  • Which part of the onion produces new roots and shoots? (The basal plate produces roots; the central part produces shoots.)
  • Why is it important that the onion base just touches the water? (Too much water can cause rotting, while too little prevents root growth.)
  • How does the onion obtain energy for initial growth? (It uses stored nutrients in the bulb.)