Photosynthetic induction in leaves of co-occurring Fagus lucida and Castanopsis lamontii saplings grown in contrasting light environments

Abstract

Photosynthetic induction times and photoinhibition in relation to simulated sunflecks (sudden increase of irradiance from 20 to 1,500 lmol m -2 s -1 ) were examined in leaves of co-occurring Fagus lucida (a deciduous tree) and Castanopsis lamontii (an evergreen tree) saplings grown either in a beech forest understory or in an adjacent open site during a late rainy season. Two hypotheses were tested: (1) understory leaves would display faster photosynthetic induction times and greater photoinhibition than open-grown leaves; and (2) evergreen species would have slower photosynthetic induction times and lighter photoinhibition than deciduous species. Times to reach 90% of maximal CO 2 assimilation rate (t 90%A ) and stomatal conductance ðt 90%g s Þ did not differ between species, but showed faster by 3-5 min in open-grown leaves than understory leaves due to higher initial stomatal conductance (g s initial ) and induction state 1 min into simulated sunflecks (IS 1min ) in the former. Our analysis across the published data on photosynthetic induction of 48 broadleaved woody species again revealed the negative correlations between t 90%A and either g s initial or IS 1min , and the similarity of t 90%A and t 90%g s between evergreen and deciduous species. Measurements of maximum PSII photochemical efficiency (F v /F m ) indicated that photoinhibition occurred in saplings in any of the growth habitats during sunfleck-induced photosynthetic induction. Despite no interspecific differences in the degree of photoinhibition, understory leaves of both species suffered heavier photoinhibition than open-grown leaves, as indicated by a stronger decrease of F v /F m in the former. Dynamic changes in the quantum yields of PSII photochemistry and DpHand xanthophyll-regulated thermal dissipation and adjustments in the partitioning of electron flow between assimilative and non-assimilative processes were functional to resist photoinhibition. However, such photoinhibition, together with stomatal and biochemical limitations, would decrease carbon gain during simulated sunflecks, particularly in understory leaves.

Systemic signalling in photosynthetic induction of Rumex K‐1 (Rumex patientia × Rumex tianschaious) leaves

“…; Mott & Woodrow ; Bai et al . ), higher Rubisco activation status (Valladares et al . ; Cao & Booth ; Bai et al .…”

“…; Mott & Woodrow ; Bai et al . ). A higher activation state of Rubisco during dark adaptation was observed in leaves that developed in a dynamic light environment compared with the leaves grown in contrasting light environments (Valladares et al .…”

Systemic induction of photosynthesis via illumination of the shoot apex is mediated by phytochrome B

“…Systemic signaling also has been observed for the regulation of photosynthesis in relation to leaf ontology in understory plants (Montgomery and Givnish, 2008). The uppermost leaves, which are generally the first to receive sunlight, display faster photosynthetic induction times than understory leaves (Bai et al, 2008). Photosynthetic induction in understory leaves is enhanced by the preillumination of upper leaves but not lower leaves, suggesting a directional signal transfer (Hou et al, 2015).…”

The physiological advantage of an ecological filter species, Indocalamus longiauritus, over co‐occurring Fagus lucida and Castanopsis lamontii seedlings

“…The measuring light of approximately 0.5 lmol m À2 s À1 was set at a frequency of 600 Hz to determine the background minimal fluorescence in the dark (F 0 ) at predawn. To obtain maximal fluorescence in the dark (F m ), saturation pulses were applied for 0.8 s. At midmorning, steady-state fluorescence (F s ) and maximal fluorescence in the light ( F 0 m ) were determined on the same leaves measured at predawn, using an actinic PPFD of approximately 1,000 lmol m À2 s À1 stabilizing for 3 min (Bai et al 2008). The partition of photons absorbed by the PSII antennae to photochemical electron transport or thermal dissipation was assessed in unity by defining and parameterizing the quantum efficiencies of photochemistry (U PSII , calculated as 1 À F s =F 0 m 1 À F s /F m ¢), DpH-and xanthophyll-regulated thermal dissipation (U NPQ , calculated as F s =F 0 m À F s =F s ) and the sum of fluorescence and constitutive thermal dissipation (U FD , calculated as F s /F m ) (Hendrickson et al 2004).…”