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