Seeds - Structure and Germination
Types of seeds and their structures
Germination is the process during which seed reserves present in the seed are broken down and the embryo starts to grow.
During germination, the seed absorbs water. Germination is irreversible i.e. once begun; the seed cannot be brought back to dormant state,
Seeds which do not germinate even after provided with all the conditions necessary for germination are called dormant seeds and the phenomenon is termed as dormancy.
Let us study what happens during germination
When a seed is germinating, the portion above the cotyledon that forms future shoots is called plumule and the portion below the cotyledon that forms the future roots is called radicle.
Conditions Necessary for Germination
As shown in the figure, take a beaker with water and place it in, a glass slide with three bean seeds tied to it.
The slide should be kept in such a way that the upper seed is completely out of water, lower seed is completely submerged in water and the middle seed is half submerged in water.
The beaker is placed in warm temperature (25° C − 30° C) for few days.
Seed at top − Does not germinate
Seed at middle − Germinates
Seed at bottom − Does not germinates
Seed at top gets only oxygen and no water. So it does not germinate.
Seed at middle receives both oxygen and water. So it germinates.
Seed at bottom gets only water and no oxygen. So it does not germinate.
Take two petridishes with moist cotton placed in it.
Place a few soaked seeds in both petridishes.
Place the first petridish in refrigerator (4°C) and the second one at room temperature (30°C).
To view the complete topic, please