XVI International Botanical Congess

Root systems are generally more prone to soil flooding than shoots. However, in amphibious and aquatic species, shoots systems possess several particularly clear-cut adaptations. Examples include escape mechanisms from submergence that involve ethylene-promoted shoot elongation in rice and Rumex palustris. In Potamogeton pectinatus, escape by means of accelerated shoot elongation is achieved over many days even when oxygen or ethylene is absent and appears to be sustained entirely by alcoholic fermentation. Where the flood water is too deep for successful escape by shoot extension, a mechanism has ben found in some rice lines that enhances tolerance to prolonged submergence.