Why Stop Flooding Rice Paddy Fields?
Rice is an unusual plant in that it can survive under flooded conditions by having some of the cells in the cortex of their roots disintegrate. (The cortex is made up of cells around the column of vascular tissues in the center of the root that transport water and nutrients upward, the xylem, and transport food supply downward, the phloem). This disintegration creates aerenchyma (air pockets) that permit air, especially oxygen, to diffuse passively from the above-ground parts of the plant eventually to the root tips, which need energy and oxygen to continue their growth. Under flooded conditions, 30 to 40% of the cortex may disintegrate this way, impairing to some extent the transport of water, nutrients and food supply within the root (Kirk and Bouldin, 1991). So, while rice plants can adapt to hypoxic, oxygen-less conditions, they do not perform at their best under such conditions. Under continuous flooding, about 3/4 of the root system degenerates by the time when the plant flowers
