A school garden has four kinds of seed that will not germinate, although they are kept wet and warm…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A school garden has four kinds of seed that will not germinate, although they are kept wet and warm. Name a treatment that could wake each one.
- Seeds of senna, with a very hard coat that water cannot enter.
- Apple seeds, taken from a fruit in autumn.
- Lettuce seeds, which germinate only in light.
- Seeds that hold a germination inhibitor, abscisic acid.
Need a reminder? The key ideaShow
A dormant seed is alive but does not germinate in good conditions. Causes: a hard coat, an immature embryo, inhibitors such as ABA, a need for cold or light. Cures: scarification, stratification, gibberellic acid, nitrate, light. ABA keeps a seed dormant and GA wakes it.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) The coat is the block, so the cure is scarification: rub it with sandpaper, nick it or shake it with sand.
Step 2. (b) Apple seeds need a cold spell, so the cure is stratification: keep the moist seeds at a low temperature for some weeks.
Step 3. (c) The cure is light: expose the seeds to light.
Step 4. (d) The cure is gibberellic acid, which works against ABA. Washing out the inhibitor with water can also work.
Answer: (a) scarification; (b) stratification; (c) light; (d) gibberellic acid or washing.
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