Erschienen in:
Canadian Journal of Forest Research, 33 (2003) 11, Seite 2164-2176
Sprache:
Englisch
DOI:
10.1139/x03-136
ISSN:
0045-5067;
1208-6037
Entstehung:
Anmerkungen:
Beschreibung:
Seasonal changes in growth, photosynthesis, and related biochemical properties and leaf structure were determined for two clones (4 and 80, 20 trees per clone) of 7-year-old Betula pendula Roth trees during the growing season of 1998. Differences between the two genotypes were determined to characterize the physiological traits that might affect growth and productivity and that might differ between the genotypes. Net photosynthesis of the short shoot leaves varied between 11 and 15 µmol·m2·s1 and decreased only slightly towards the end of the summer. However, our results showed more marked decreases in the amount of Rubisco (ribulose biphosphate carboxylase/oxygenase) and leaf N and increases in the total leaf, palisade and spongy layer thickness, chloroplast and starch grain size, and diameter of plastoglobuli in both clones in response to leaf ageing and changes in growth environment. Height and biomass were greater in clone 80 than in clone 4. This was related to slightly more efficient net photosynthesis and higher stomatal conductance and density as well as higher activity of Rubisco and content of foliar nutrients (other than N). We conclude that clone 80 is characterized by faster gas exchange, higher Rubisco activity, stomatal conductance, and density, and earlier leaf ageing, which may be related to the higher ozone sensitivity determined previously in pot experiments with younger saplings.