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Seed Germination

Middle schoolBiologySeeded individual germination thresholds under illustrative moisture, oxygen and temperature responses

Click any of the 24 seeds to inspect its root and shoot. Compare dry, oxygen-poor and waterlogged trays, or jump to the next radicle emergence.

3D

Drag the apparatus to adjust it. Drag the background to rotate. Scroll to zoom.

Measurement notebook

Change the setup, test a prediction and save the result. Up to 12 snapshots are kept.

About this experiment

Observe a tray of 24 individual seeds, inspect their radicles and compare the same seeded population under different conditions. Investigate dry, oxygen-poor and waterlogged trays without replacing the result with a random percentage.

Learning goals

  • Identify radicle emergence as the germination criterion used here.
  • Explain why both water and oxygen are needed in this model.
  • Separate a fixed viability limit from delayed emergence under poor conditions.

How to use it

  1. 1Run a moist, aerated tray and select a seed to inspect.
  2. 2Jump to the next radicle emergence and compare the tray count with individual states.
  3. 3Repeat with zero water, zero oxygen and high water availability.
  4. 4Change the tray seed and compare a new reproducible set of individuals.

The model

The specified environmental response sets the common threshold accumulation rate.
The reported tray count sums explicit individual emergence states.

Assumptions

  • Every tray contains 24 seeds with fixed seeded viability flags and emergence thresholds. Conditions change their common emergence rate while preserving that seed sequence.
  • The temperature response is a Gaussian centred on 25 °C. Moisture increases hydration, while heavy waterlogging reduces effective oxygen through a specified illustrative factor.
  • A viable seed emerges when accumulated rate times time exceeds its threshold. Zero water or oxygen prevents emergence in the observation window.
  • Root growth after emergence follows a square-root age curve; shoot growth begins after an additional day. These lengths and times are schematic, not calibrated species data.
  • An un-emerged seed may be delayed or nonviable. The display does not claim to diagnose its viability from appearance.

Try this in class

  1. Q1Why can adding more water eventually reduce effective oxygen?
  2. Q2Why is a short experiment insufficient to classify every un-emerged seed as dead?

Frequently asked questions

Why does the same seed emerge at the same time when settings are repeated?

The model uses a fixed seeded set of individual thresholds and deterministic environmental responses.

Does this include dormancy and every germination cue?

No. Light requirements, cold treatment, scarification, infection and species-specific dormancy are omitted.