Oxygen for roots

​Respiration in corn roots, like respiration in the leaves is the process in which glucose is broken down into a chemically useable form of energy (ATP), CO2 and H20.  This process requires oxygen (O2).  Obtaining oxygen for leaves is available from the atmosphere as it passes through leaf stomata, but how does it get into roots? 
 
Root hairs, those fine extensions of the root epidermis, have thin walls that allow absorption of minerals, and passes of gases such as oxygen existing in small air pockets in the soil.  These root hairs also allow the passage of CO2 from respiration to move outside the root tissue.  Absorption of oxygen allows the respiration within the cells, in mitochondria, to release energy for other root activity including cell division and active transport of nutrients to other parts of the plant.  Experiments with other plant species grown in water culture have shown that roots grew larger and with more root hairs when the water was aerated versus non-aerated. More root tissue with more root hairs increases mineral absorption, better transport of water and minerals to above ground parts and less vulnerability to lodging as the plant grows.
 
Soil compaction and excessive water that reduces oxygen available to roots can have a detrimental effect on corn plants for the whole season if the flooding is prolonged.