3.3 Chl content in leaf and non-photochemical quenching decay
components: NPQfast, slow
The total Chl content in untreated SA leaves under salt treatment
was around 4.5 times higher than that in untreated SV leaves
(Figure 4A-B). Exposure of SV to NaCl resulted in a progressive
decrease in Chl content (Figure 4A); the total Chl concentration after
12 days of salt treatment with 50 and 100 NaCl dropped by 42% and 58%,
respectively. In contrast, treatment of SA with 50 and 100 NaCl
did not result in any significant decline in the total Chl content
except at NaCl concentrations higher than , e.g. at NaCl treatment,
there as a ~20% decrease in total Chl content (Figure
4B).
In SV , NaCl treatment resulted in an increase of NPQ, while NPQ
remained similar or oightly increased in SA at all NaCl
concentrations (Figure 4C-D). The NPQ increase in SV might be
resulted from a modulation of either a protective high-energy-state
quenching or otoinhibition, which differ in the relaxation kinetics
after actinic light illuminationell & Johnson, 2000; Johnson et al.,
2009). MeasurementNPQ were taken after 16 daosure to 100 and 400 mM NaCl
treatments for SV and SA , respectively (Figure 4C-D). The
NPQ recovery under darmeasured to quantify the magnitude of each phase
of NPQ dark decay. In SV , quantification of the fast and slow
relaxing components of NPQ quenching showed that the majority of
quenching relaxed rapidly in the dark (NPQf), indicating that it was
high-energy-state quenching (Figure 4C-D); while a part of the quencas
more conservative (NPQs), suggesting the occurrence of photoinhibition
in leaves of SV due to high NaCl. Both forms of NPQ quenching
increased in response to salt treatment (Figure 4C-D). The increase in
total NPQ in SA was comparatively less and was mainly due to an
increase in NPQf (photoprotection process).