How does the amount of oxygen in the water affect the growth of a plant ? ?

Increasing the amount of dissolved oxygen (DO) increases the amount of plant growth; decreasing DO decreases plant growth.

If a plant's roots don’t get enough oxygen, their membranes become less permeable.

They can no longer absorb nutrients properly, so they begin to die.

Plant growth slows down because its no longer receives enough of the required nutrients.

Increasing the amount of DO causes a marked increase in the growth rate.