THE CHEMICAL-COMPOSITION OF XIPHOPHORA-GLADIATA (PHAEOPHYCEAE, FUCALES) - SEASONAL AND WITHIN PLANT VARIATION

Mannitol, tissue nitrogen, tissue carbon, C/N ratio and ash contents were determined for different parts of three size classes of Xiphophora gladiata subsp. novae-zealandiae Rice plants from March 1987 to February 1988. Seasonal differences were found for all size plants and all components analysed. Mannitol content showed higher values in the summer and autumn (November-May) months with levels increasing from the base to the apex of the plant. Less variation was seen between plant parts during winter (June-August). Tissue nitrogen levels were maximal between October and December with the middle parts of the plant showing highest levels. Tissue carbon values were also higher in the middle parts of the plant. Carbon and C/N ratio showed the opposite pattern to nitrogen. For the smallest plants (15-30 cm) the ash content was the only component that showed a significant difference between parts of the plant. In contrast, plants 30-45 cm showed significant differences between parts of the plant for all components analysed. Plants greater in length than 45 cm showed significant differences between parts of the plant for nitrogen and carbon.