Describe what occurs when seeds germinate. What environmental conditions are needed to begin the germination?

Question

please and thank you~

Answer 1

Some seeds sprout with just water and reasonably warm temperatures. This is true of most common garden plants.

Wild species usually have some kind of deeper dormancy to avoid sprouting in late summer/fall when the seeds are dispersed. This assures that tender seedlings are not frozen at a young age, but do not appear until warm weather arrives in springtime.

If a species has evolved a very thick seed coat, it may require scarification of that seed coat before water can enter the seed and initiate germination. Perhaps the coat has to be gnawed at by animals, or frozen and thawed repeatedly to crack the coat, or rund down the rocks in a stream bed or up beach in pounding surf to wear the coat down. Perhaps the seed is swallowed whole by the disperser. The thick seed coat protects the dormant embryo as it passes through the animal's digestive system. The weakening of the seed coat through digestion means that the seed is ready to sprout when it gets deposited (along with a bit of fertilizer) by the disperser somewhere new in the environment. Yet other seeds require a brief exposure to fire to scarify the seed coat.

In species with thin seed coats, light may be able to penetrate into the dormant embryo. The embryo may then either use the presence of light or the absence of light to trigger its germination process. Small seeds with thin seed coats are likely to use light as a signal for germination

A large seed in the opposite is provided with lots of investment in storage to wait until it is buried before sending up its shoot. Such a seed will key in on darkness rather than light.

One can say that all seeds are adapted to their environment and use adaequate mechanisms and conditions to germinate.

In this publication you find lot of these specializations:

http://plantphys.info/plants_human/seedg...

and here some supplementary images:

http://images.google.de/imgres?imgurl=ht...