Recovery of photosynthesis in winter‐stressed Scots pine
During winter, high light and freezing temperatures interact to cause damage to photosynthesis of pine (1). The photochemical efficiency of photosystem II (PS II), the quantum yield and the rate of light saturated photosynthesis are severely inhibited during natural winter conditions. Strand and Oquist (2, 3) have shown that winter stress of Scots pine involve both photoinhibition of photosystem II and frost inhibition of the enzymes in the Calvin cycle or the photophosphorylation. In the field it may take several months before full photosynthetic efficiency is restored after the winter (4, 5).