Why does water-logged soil kills a plant's root?

Question

Why does water-logged soil kills a plant's root?

Answer 1

Plants need to breathe and over watering the roots don't allow them to breathe.  The roots become overwhelmed with water and the root begins to break down and rot.  By allowing a plant enough water to have a "drink" and by maintaining moist soil (if necessary, a lot of plants like dry soil before re-watering) the roots have a chance to breathe, grow and develop a healthy base structure, resulting in a healthy plant. There are some plants that do survive happily in water-logged soil.  Check out your local pond (bull-rush, lily pads etc.)

Answer 2

because that particular plant likes a drained soil

there are millions  of plants each has its own preference of soil conditions and quality

there are water anchored plants that like to stand in water,

others that grow on edges of rivers and ponds can handle being water logged either permanently of half of the year

but the majority of plants  live on the drained   land they will die in water logged conditions

just as the water plants will die if they are too  dry

Answer 3

The roots get suffocated by the water innundation

Answer 4

Causes root rot.