期刊
TREE PHYSIOLOGY
卷 27, 期 11, 页码 1607-1617出版社
OXFORD UNIV PRESS
DOI: 10.1093/treephys/27.11.1607
关键词
chlorophyll; maximurn photosynthetic rate; phosphorus; photosynthetic biochemistry; relative irradiance; rubisco; stoinatal conductance
类别
A significant and well-supported hypothesis is that increased growth following nitrogen (N) fertilization is a function of the relationships among photosynthesis, tissue N content and the light environment-specifically, the within canopy allocation of N among leaves and the within-leaf allocation of N between Rubisco and chlorophyll. We tested this hypothesis in a field trial that included annual applications of N,P,K fertilizer (from planting) to a Eucalyptus globulus Labill. plantation growing on uniform leached sands. Growth of 4-year-old E. globulus increased significantly in response to fertilization. Leaf N and phosphorus concentrations were 0.1-0.5 gm(-2) and 0.4-0.5 gm(-2) higher in fertilized trees compared to unfertilized trees, respectively. Stomatal conductance (g(s)) at the maximum photosynthetic rate (A(max)) was between 0.2 and 0.4 mol m(-2) s(-1) higher in fertilized trees, but A(max) and the concentration of Rubisco (Rub(a)) were unaffected by fertilization. This seeming paradox, where there was no response of A(max) to fertilization despite increases in g(s) and leaf N concentration, was explained by reduced in vivo specific activity of Rubisco in fertilized trees. Acclimation to light, measured by redistribution of N between Rubisco and chlorophyll, was unaffected by fertilization. Distribution of leaf N followed irradiance gradients, but A(max) did not. Maximum photosynthetic rate was correlated with leaf N concentration only in unfertilized trees. These findings indicate that the relationships among photosynthesis, N and the light environment in E. globulus are affected by N,P,K fertilization.
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