Limits to photosynthesis: seasonal shifts in supply and demand for CO2 in Scots pine.
New Phytol
; 233(3): 1108-1120, 2022 02.
Article
em En
| MEDLINE
| ID: mdl-34775610
ABSTRACT
Boreal forests undergo a strong seasonal photosynthetic cycle; however, the underlying processes remain incompletely characterized. Here, we present a novel analysis of the seasonal diffusional and biochemical limits to photosynthesis (Anet ) relative to temperature and light limitations in high-latitude mature Pinus sylvestris, including a high-resolution analysis of the seasonality of mesophyll conductance (gm ) and its effect on the estimation of carboxylation capacity ( VCmax ). We used a custom-built gas-exchange system coupled to a carbon isotope analyser to obtain continuous measurements for the estimation of the relevant shoot gas-exchange parameters and quantified the biochemical and diffusional controls alongside the environmental controls over Anet . The seasonality of Anet was strongly dependent on VCmax and the diffusional limitations. Stomatal limitation was low in spring and autumn but increased to 31% in June. By contrast, mesophyll limitation was nearly constant (19%). We found that VCmax limited Anet in the spring, whereas daily temperatures and the gradual reduction of light availability limited Anet in the autumn, despite relatively high VCmax . We describe for the first time the role of mesophyll conductance in connection with seasonal trends in net photosynthesis of P. sylvestris, revealing a strong coordination between gm and Anet , but not between gm and stomatal conductance.
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01-internacional
Base de dados:
MEDLINE
Assunto principal:
Pinus sylvestris
Idioma:
En
Revista:
New Phytol
Assunto da revista:
BOTANICA
Ano de publicação:
2022
Tipo de documento:
Article
País de afiliação:
Suécia