Question

How did the roots take oxygen?

Answer 1

Roots never take o2
Only stem can take with the help of guard cells
Guard cells is helpful for gaseous exchange
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Answer 2

This has been bothering me for a long time. It should be a silly question for you:

Field-plants developed root rots when drowned by water. We know roots require oxygen to breath. But people, including myself, grow plants in the water and give this practice a cool name. Every time I look at those perfectly white, but totally submerged roots, I wonder how the roots survive?

My guesses:

(1) Far more plant pathogens live in the soil than in artificial water solution made from chlorine-treated tap water. The suffering submerged roots just lack the usual enemies to finish them off.

(2) The leaves, which makes oxygen during photosynthesis, can ship a small portion of oxygen products down to the root. As long as there is not too much root to feed, and there is a reasonable amount of oxygen dissolved in the water bath, the roots can survive.

(3) Some root sections are slightly above water. They breath liberally and sends down the oxygen.

(4) People lift up their hydroponic plant frequently to change/add water and to look at the roots. During these short seconds, the roots take a huge gasp.

Any ideas?