especially if it occurs during early vegetative stage and prolongs
for more than a week (Mohanty et al., 2000). The flooding of
root systems and partial to complete submergence of aerial
organs can dramatically reduce crop productivity. Most nonaquatic
plants are damaged by transient inundation of aerial
tissue for 24–48 h; exceptionally rice (Oryza sativa) is generally
tolerant of submergence. When rice plants subjected to flash
floods, they should adapt themselves to two drastic environmental
changes: the changes from aerobic to hypoxic condition
during complete submergence and the subsequent changes from
hypoxic to aerobic condition when the floodwater recedes. The
visual damage caused by the submergence is generally not
apparent immediately but develops soon after the water level
recedes after complete submergence. Deepwater rice and the
widely cultivated lowland rice overcome submergence stress by
antithetical strategies (Fukao and Bailey-Serres, 2004). The direct
sunlight also threatens leaves accustomed to low-light underwater
environments, causing the photosynthetic apparatus to be
photo inhibited (Osmond, 1994).