GERMINATION TRIGGERS

Monday, March 14, 2011

Some seeds germinate in response to the length of daylight and the soil temperature. Tiny poppy seeds and winter savory will only begin to grow either in the presence of strong light or large temperature fluctuations, both of which occur only when the seed is on or near the surface. This ensures that it has enough food in its tiny reservoir to reach the light. This is also why earth moving, which brings buried seed up to the surface, gives crop of poppies the following summer and why the battlefields of Flanders produced their heartwarming display during the First World War.

When a seed registers that adequate conditions for germination have arrived, it allow moisture to penetrate the seed coat which swells the seed leaves inside until they push open the seed. The embryo divides into two parts, sending first a radical downwards in response to gravity to anchor the plant in the soil. When this begins to grow root hairs the seed sends a shoot upward into the light to grow leaves.