Abstract:
The dependence of photosynthetic CO2 assimilation upon irradiance has been known for a long time, and many studies have revealed strong correlations between photosynthesis and leaf nitrogen (N) content in various plant species.
However, the effects of N nutrition on grapevine gas exchange have usually been investigated at light saturation, although overcast situations occur rather frequently in temperate zone viticulture.
Thus, the impact of adverse weather conditions on the grapevine's response to soil N level is not clear.
The flowering period is crucial for reproductive growth, since stress situations impairing photosynthesis may result in a shortage in carbon translocation to the flower cluster, which are low-priority sinks.
The purpose of this study was therefore to evaluate the combined effects of N supply and limiting irradiance at bloom on gas-exchange, N uptake and N as well as carbon (C) and dry matter partitioning.
We were also interested in the effect of N on the vines' capability for the leaves' restricted source-capacity.
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