MECHANISM OF FLOOD TOLERANCE IN REED, PHRAGMITES-AUSTRALIS (CAV) TRIN EX STEUDEL

Important factors, such as porosity, respirational O2 consumption, O2 release of the roots and iron oxidation on the root surface, which are involved in the flood tolerance of Phragmites australis were investigated in northern Germany. The porosity of the different organs was determined as 58% for rhizomes, 42% for culms and 23‐38% for adventitious roots. Mean respirational O2 consumption of below ground organs was measured at 5, 10, 15 and 20°C as respectively 0.25, 0.5, 0.8 and 1.75 nmol O2 g−1dry mass s−1. The saturation concentration was estimated to be less than 0.017 mmol O2 1−1up to 15°C and 0.03 mmol O2 1−1at 20°C. From values of the root O2 gas exchange obtained from entire plants predictions are made concerning the O2 status of the roots under field conditions throughout the year. The O2 release for a reed stand was calculated as 65‐129 mg O2 m−2h−1in summer conditions. The oxidation power of the roots was further demonstrated by the development of iron hydroxide‐plaques on the root surface. Copyright © 1990, Wiley Blackwell. All rights reserved