Living Creatures: Exploring their Characteristics
What seeds need to sprout
Investigate what seeds need to sprout.
When a seed turns into a sprout, we say it has germinated. What does a seed need to germinate? Your book sows bean seeds in four pots of garden soil:
| Pot | Water | Light | Result |
|---|---|---|---|
| A | none (dry soil) | direct sunlight | does not germinate: no water |
| B | so much that water always stands above the soil | direct sunlight | does not germinate: no air |
| C | slightly moist soil | dark | germinates |
| D | slightly moist soil | direct sunlight | germinates |
Conclusion: bean seeds need the right amount of water and air to germinate. Light is not needed: the seeds in the dark pot sprouted too.
Why water? A seed's outer covering is the seed coat. Soak a seed overnight and feel how soft it becomes. Water softens the seed coat and helps the tiny embryo inside grow into a plant.
Why air? Seeds use the air in the spaces between soil particles. These spaces also let roots grow easily. When water fills every space, there is no air left.
Light? Most seeds, like beans, do not need light to germinate, but once sprouted, the seedling needs sunlight to keep growing. Seeds differ, though: Coleus and Petunia need light to germinate, so covering them with soil stops them sprouting; Calendula and Zinnia need darkness, so they should be covered with enough soil.
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