CONTENT OF WATER-SOLUBLE CARBOHYDRATES UNDER OXYGEN DEPRIVATION IN PLANTS WITH DIFFERENT FLOODING TOLERANCE

We investigated the carbohydrate concentration of plant species natura lly growing in habitats with a high risk of oxygen shortage (Senecio a quaticus HILL, Myosotis palustris (L.) L. em. RCHB.) and congeneric sp ecies from drier sites (Senecio jacobaea L., Myosotis arvensis (L.) HI LL). Plants from the four species were cultivated in either nitroge-fl ushed or aerated nutrient solution. Following oxygen shortage in the r oot environment a two - fourfold increase of carbohydrate content was found in the roots as well as in the shoots of the species examined. A lthough the tendency in the response of both genera to the hypoxic con ditions in the nutrient solution was the same, there were differences in concentration and composition of the water soluble carbohydrates. T he flooding tolerant Senecio aquaticus accumulated the highest amounts of carbohydrates, in particular fructans (nearly 60% of the soluble c arbohydrates, compared with 30% under aerated conditions). The increas ing amount of sugars found under hypoxia-inducing conditions proved th at substrate availability was not the limiting factor for survival und er wetland conditions.