Storage carbohydrate production and overwintering strategy in a winter-green tussock grass on South Georgia (Sub Antarctic)

Water-soluble and ethanol-soluble carbohydrates were extracted from leaves, shoots, roots, rhizomes and flowers ofParodiochloa flabellata (Lam.) Rasp. (=Poa flabellata (Lam.) Hook f.) throughout a growing season. Very high levels of soluble carbohydrates were found in the shoot, comprising up to 71% of the shoot dry weight. There was no significant storage in the rhizome. It is suggested that the production of storage fructans with a degree of polymerization greater than 14, rather than oligosaccharides or starch, may be related to the cold environment. Relationships between the onset of senescence and levels of fructans suggest that recovery of sugars from dying tissue is high. The sugar reserves together with preformation of the flowers should ensure production of seed however poor the summer or long the winter might be. The high levels of fructans may partly inhibit growth but may also offer some degree of freezing resistance.