The most ubiquitous plant abiotic stress in the global
environment is generally thought to be water deficit.
The opposite of water-deficit stress. flooding, initially
involves relief of the abiotic factor of water deficit and
only becomes stressful after flooding persists long
enough to directly or indirectly interfere with a variety
of plant functions via several mechanisms. The
relief of stress with short term flooding (typically a
day or less) is the principle upon which irrigation
hinges. By contrast, the negative impacts of prolonged
flooding on ecosystems, and particularly agricultural
production systems, are substantial [I] and
may be as significant as drought, depending on one's
accounting strategy. Much of this impact is the result
of the combination of soil and plant chemical, physical,
and biological changes that cause stomata to
close after prolonged flooding. This contributes significantly
to a drastic reduction in photosynthesis and
damages many other plant functions by disrupting
transpiration and the complex system of hormonal
control of plant systems and processes
