Improved elongation of Scots pine seedlings under blue light depletion is not dependent on resource acquisition

Removal of blue light (400-500 nm) induced shoot elongation of 2-year-old Scots pine (Pinus sylvestris L.) seedlings, which was not related to resource acquisition (carbohydrates, C/N ratio and soluble proteins) and frost hardening. The seedlings were grown in northern Finland (64°N) in plexiglass chambers, either orange in colour or transparent, during elongation and cold hardening periods in 2001. The orange chamber removed the blue wavelengths. The results suggest that the growth inhibiting effect of blue light on Scots pine elongation is probably a photomorphogenic regulation response; the removal of blue light did not affect the gas exchange and accumulation of growth resources. In addition, the removal of blue light also did not affect the physiological parameters (pigment composition, chlorophyll fluorescence and lipid peroxidation) measured during the preparation for winter.