Kohlehydratgehalte und Vitalität isolierter Rhizome von Phragmites australis, Schoenoplectus lacustris und Typha latifolia nach mehrwöchigem O2-Mangelstreß

Abstract

The lowest levels of carbohydrate reserves were found in summer in the rhizomes of Phragmites communis, Schoenoplectus lacustris and Typha latifolia. Detached rhizomes of these plants were placed under oxygen deprivation stress for 1—3 weeks and then restored to air to give a total experimental time of 6 weeks. During the oxygen stress there was a reduction in carbohydrate reserves in all the species. Schoenoplectus lacustris possessed the greatest starch reserves and during the period of stress mobilised starch, while the free sugar concentration remained unchanged. In Phragmites australis and Typha latifolia both free sugars and starch were reduced. Typha latifolia in contrast to the other species survived only two weeks of oxygen stress. Six weeks after the beginning of the experiment the rhizomes were tested for vitality and regeneration ability. Schoenoplectus lacustris rhizomes always contained the greatest carbohydrate reserves and not only survived the anoxic treatment but quickly grew both roots and green shoots during the subsequent period of aeration. Phragmites australis possessed smaller carbohydrate reserves yet regenerated successfully after all the experimental stress treatments. Typha latifolia however survived only partially, did not grow either new shoots or roots and showed a continually falling level of carbohydrate reserves. In Phragmites australis and Schoenoplectus lacustris the supply of carbohydrate was assured both by the availability of sufficient reserves and the prompt re-establishment of photosynthesis. In Typha latifolia the low level of carbohydrate reserves present in summer limited its tolerance of oxygen deprivation.