Oxygen to plant roots

HHenjum hhenjum at aol.com
Sat Jun 24 19:03:47 EST 1995

Plants DO need O2-to live and grow. Oxygen is required for resperation by
all (living) cells in plants.Photosynthesis produces enough for near by
cells during the day, but much of it leeks away and very little is
transported with in the plant -  including the roots. thus leaves at night
absoed O2 from the air, and roots require O2 that is traped in the soil-
the entry of O2 is by diffusion because there is no special transport
mechanism like blood in animals for O2 movment through the plant.
  O2 leavals in soil are dependent on two conditions, 1) pore space. 2)
water content.
Pore space effects O2 movement from the air through the soil and water
effects the amount of pore space the soil has. water saturated soil
contains no pore space thus free O2 is limited to that which is dissolved
into the water- and the plant can not move enough of this water to keep in
contact with water that is still O2 rich.
Yes rice, swamp and mash plants including cypress-TAXODIUM  and sedges
have large air spaces running through the stems that help O2 movement
through the plant and some water grownig plants have roots that grow to
the surface of the water to transport O2 to the other roots from the air. 

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