Carbohydrate storage in rhizomes of Phragmites australis: the effects of altitude and rhizome age

Starch, glucose, fructose and sucrose were measured in nodes and internodes of horizontal rhizomes of Phragmites australis in two localities, at 400 a nd 1350 m above sea level respectively, before spring growth started. In th e respective localities, five and four age categories of rhizomes were dist inguished. Rhizomes of lowland plants, harvested on March 21, contained mor e starch (17.6%), glucose (2.5%) and total non-structural carbohydrates (35 .2%) per gram dry mass than rhizomes of plants collected at the tree line o n June 3 (11.8, 1.7 and 30.5%, repectively). The proportion of water solubl e carbohydrates to total non-structural carbohydrates, as an indication of acclimatisation to a cold climate, was higher in the mountain locality (60 and 49%, respectively). Glucose and starch concentrations increased with rh izome age in both localities. All other carbohydrate fractions were indepen dent of locality. Water soluble carbohydrates were preferentially accumulat ed in internodes whereas starch was accumulated in nodes. (C) 1999 Elsevier Science B.V. All rights reserved.