There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.
Abstract
The photosynthetic capacity of leaves is related to the nitrogen content primarily
bacause the proteins of the Calvin cycle and thylakoids represent the majority of
leaf nitrogen. To a first approximation, thylakoid nitrogen is proportional to the
chlorophyll content (50 mol thylakoid N mol-1 Chl). Within species there are strong
linear relationships between nitrogen and both RuBP carboxylase and chlorophyll. With
increasing nitrogen per unit leaf area, the proportion of total leaf nitrogen in the
thylakoids remains the same while the proportion in soluble protein increases. In
many species, growth under lower irradiance greatly increases the partitioning of
nitrogen into chlorophyll and the thylakoids, while the electron transport capacity
per unit of chlorophyll declines. If growth irradiance influences the relationship
between photosynthetic capacity and nitrogen content, predicting nitrogen distribution
between leaves in a canopy becomes more complicated. When both photosynthetic capacity
and leaf nitrogen content are expressed on the basis of leaf area, considerable variation
in the photosynthetic capacity for a given leaf nitrogen content is found between
species. The variation reflects different strategies of nitrogen partitioning, the
electron transport capacity per unit of chlorophyll and the specific activity of RuBP
carboxylase. Survival in certain environments clearly does not require maximising
photosynthetic capacity for a given leaf nitrogen content. Species that flourish in
the shade partition relatively more nitrogen into the thylakoids, although this is
associated with lower photosynthetic capacity per unit of nitrogen.