IMPLICATIONS OF MISSING EFFLUX SITES ON CONVECTIVE VENTILATION AND AMINO-ACID-METABOLISM IN PHRAGMITES-AUSTRALIS

Three stands of Phragmites australis (Cav.) Trin. ex Steudel were inve stigated regarding the relationship between the number of efflux culms and convective ventilation efficiency affecting the hypoxic status of roots and rhizomes. The lack of old (efflux) culms after mowing the p receding winter caused a significantly higher counterpressure within t he rhizome, thereby diminishing air flushing rate, i.e. oxygen supply, of rhizomes. The levels of alanine and gamma-aminobutyric acid in bas al culm internodes increased significantly. Both amino acids indicate the hypoxic status of the soot and rhizome metabolism of P. australis. Amino acid patterns of the basal culm internodes are discussed with r espect to the maintenance of aerobic root metabolism and nutrient avai lability.