INFLUENCE OF ROOT OXYGEN DEFICIENCY ON PHOTOSYNTHESIS AND SACCHARIDE CONTENTS OF CAREX SPECIES

The responses to root oxygen deficiency concerning the photosynthesis, saccharide contents and mineral uptake have been investigated in Care x species, which were different in their anoxia-tolerance. The net rat e of photosynthesis (P-N) of the anoxia-sensitive C. extensa was not a ffected by root anaerobiosis. Despite short-term effects of root anaer obiosis on P-N values in the anoxia-tolerant species C. remota and C. pseudocyperus, root oxygen supply did not influence P-N, when the plan ts were allowed to acclimate. The saccharide contents of the anoxia-to lerant species were almost not affected by prolonged anaerobiosis. 40 days of root oxygen deficiency led to significant changes in the shoot saccharide composition of C. extensa: contents of glucose and fructos e were increased 4-fold and sucrose content was significantly decrease d. In the roots no sucrose could be detected, but the starch content w as increased, and the glucose and fructose contents did not change whe n compared with aerobic conditions. Under anaerobic conditions, minera l uptake of the anoxia-sensitive species decreased by 50%, while the m ineral uptake of the anoxia-tolerant species was significantly increas ed or did not change at all, in comparison with the aerobic conditions . The growth reduction of C. extensa under anaerobic conditions was th erefore primarily due to inability to take up an adequate amount of nu trients.