Atmospheric and climate change will expose tropical forests to
conditions they have not experienced in millions of years. To better
understand the consequences of this change we studied photosynthetic
acclimation of the neotropical tree species Tabebuia rosea to
combined 4°C warming and twice-ambient (800 ppm) CO. We
measured temperature responses of the maximum rates of ribulose
1,5-bisphosphate carboxylation (V), photosynthetic
electron transport (J), net photosynthesis
(P), and stomatal conductance (gs), and fitted the
data using a probabilistic Bayesian approach. To evaluate short-term
acclimation plants were then switched between treatment and control
conditions and re-measured after 1–2 weeks. Consistent with
acclimation, the optimum temperatures (T) for
V, J and P
were 1–5°C higher in treatment than in control plants, while
photosynthetic capacity (V, J,
and P at T) was 8–25% lower.
Likewise, moving control plants to treatment conditions moderately
increased temperature optima and decreased photosynthetic capacity.
Stomatal density and sensitivity to leaf-to-air vapor pressure deficit
were not affected by growth conditions, and treatment plants did not
exhibit stronger stomatal limitations. Collectively, these results
illustrate the strong photosynthetic plasticity of this tropical tree
species as even fully-developed leaves of saplings transferred to
extreme conditions partially acclimated.
Flexibility of C4 decarboxylation and photosynthetic plasticity in sugarcane plants under shading
