Photoprotection, photosynthesis and growth of tropical tree seedlings under near-ambient and strongly reduced solar ultraviolet-B radiation

Krause, G. Heinrich; Jahns, Peter; Virgo, Aurelio; García, M.; Aranda, Jorge; Wellmann, Eckard; Winter, Klaus

doi:10.1016/j.jplph.2006.09.004

Cited by 16 publications

(10 citation statements)

References 58 publications

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“…In Arabidopsis thaliana , pre‐exposure to UV‐B increased the tolerance to high light conditions via increased recovery of TR o /ABS (Poulson et al 2006). Another study showed that some acclimated leaves from reduced UV‐B treatment had high susceptibility to UV‐B‐mediated photoinhibition upon transfer to a high irradiance level of ambient solar radiation, but after a short period no effects were seen, demonstrating a capacity for rapid acclimation to UV‐B in the investigated tropical tree seedlings (Krause et al 2007). In our study, B. nana did not acclimate to avoid the negative impacts of solar UV‐B, even after long‐term experimentation.…”

Section: Discussionmentioning

confidence: 99%

Solar UV‐B effects on PSII performance in Betula nana are influenced by PAR level and reduced by EDU: results of a 3‐year experiment in the High Arctic

Mikkelsen¹,

Ro‐Poulsen

Arndal

et al. 2012

Physiologia Plantarum

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The long-term and diurnal responses of photosystem II (PSII) performance to near-ambient UV-B radiation were investigated in High Arctic Betula nana. We conducted an UV exclusion experiment with five replicated blocks consisting of open control (no filter), photosynthetic active radiation and UV-B transparent filter control (Teflon), UV-B-absorbing filter (Mylar) and UV-AB-absorbing filter (Lexan). Ethylenediurea (EDU), a chemical normally used to protect plants against ozone injury, was sprayed on the leaves both in the field and in an additional laboratory study to investigate if EDU mitigated the effects of UV-B. Chlorophyll-a fluorescence induction curves were used for analysis of OJIP test parameters. Near-ambient UV-B radiation reduced across season maximum quantum yield (TR(o) /ABS = F(v) /F(m)), approximated number of active PSII reaction center (RC/ABS) and the performance index (PI(ABS)), despite improved leaf screening against UV-B with higher content of UV-B-absorbing compounds and a lower specific leaf area. EDU application counteracted the negative impact of UV-B on TR(o) /ABS, RC/ABS and PI(ABS) . This indicates that the mechanisms behind UV-B and ozone damage share some common features. The midday depression was present in all treatments, but TR(o) /ABS and PI(ABS) were persistently lower in near-ambient UV-B compared to UV-B reduction. The recovery phase was particularly impaired in near-ambient UV-B and interactive effects between treatment × hour raised TR(o) /ABS, RC/ABS and PI(ABS) higher in reduced UV-B compared to near-ambient UV-B. This demonstrates current solar UV-B to reduce the PSII performance both on a daily as well as a seasonal basis in this High Arctic species.

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Section: Discussionmentioning

confidence: 99%

Solar UV‐B effects on PSII performance in Betula nana are influenced by PAR level and reduced by EDU: results of a 3‐year experiment in the High Arctic

Mikkelsen¹,

Ro‐Poulsen

Arndal

et al. 2012

Physiologia Plantarum

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“…In addition, the growth of six shade-tolerant species was negatively correlated to irradiance. Shadetolerant species may experience photo-inhibition and poor growth in sunflecks lasting 10 minutes or longer (Le Gouallec et al 1990, Krause et al 2007, which can contribute 10-85% of daily light levels (Pearcy 2007). The inverse relationship between low-light survival and magnitude of growth responses to nutrients conflicts with other studies (Denslow et al 1987, Lawrence 2001) that examined only P and inorganic N. Our results suggest that shade-tolerant species have a lower nutrient demand.…”

Section: Discussionmentioning

confidence: 99%

Seedling growth responses to soil resources in the understory of a wet tropical forest

Holste

Kobe

Vriesendorp

2011

Ecology

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Plant growth responses to resources may be an important mechanism that influences species' distributions, coexistence, and community structure. Irradiance is considered the most important resource for seedling growth in the understory of wet tropical forests, but multiple soil nutrients and species have yet to be examined simultaneously with irradiance under field conditions. To identify potentially limiting resources, we modeled tree seedling growth as a function of irradiance and soil nutrients across five sites, spanning a soil fertility gradient in old-growth, wet tropical forests at La Selva Biological Station, Costa Rica. We measured an array of soil nutrients including total nitrogen (total N), inorganic N (nitrate [NO3-] and ammonium [NH4+]), phosphate (PO4-), and sum of base cations (SBC; potassium, magnesium, and calcium). Shade in the forest understory did not preclude seedling growth correlations with soil nutrients. Irradiance was a significant predictor of growth in 52% of the species, inorganic N in 54% (NO3- in 32%; NH4+ in 34%), total N in 47%, SBC in 39%, and PO4- in 29%. Overall, growth was correlated with both irradiance and soil nutrients in 45% of species and with soil nutrients only in an additional 48%; rarely was irradiance alone correlated with growth. Contrary to expectations, the magnitudes of growth effects, assessed as the maximum growth response to significant resources for each species, were similar for irradiance and most soil nutrients. Among species whose growth correlated with soil nutrients, the rank importance of nutrient effects was SBC, followed by N (total N, NO3-, and/or NH4+) and PO4-. Species' growth responsiveness (i.e., magnitudes of effect) to irradiance and soil nutrients was negatively correlated with species' shade tolerance (survival under 1% full sun). In this broad survey of species and resources, the nearly ubiquitous effects of soil nutrients on seedling growth challenge the idea that soil nutrients are less important than irradiance in the light-limited understory of wet tropical forests.

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“…The degree to which fully acclimated sun or shade leaves can adjust their UV filtering and UV‐absorbing compounds in response to sudden changes in their light regimes remains unclear. Some studies have shown that mature leaves or leaf segments are generally unresponsive in their UV‐sunscreen capacities when confronted with changes in the environment (Nybakken et al , Bilger et al , Štroch et al ), whereas others indicate that the UV‐shielding response is more dynamic and plastic (e.g., Krause et al , Barnes et al , Agati et al , Morales et al ).…”

Section: Introductionmentioning

confidence: 99%

Adjustments in epidermal UV‐transmittance of leaves in sun‐shade transitions

Barnes

Kersting

Flint

et al. 2013

Physiologia Plantarum

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Epidermal UV transmittance (TUV ) and UV-absorbing compounds were measured in sun and shade leaves of Populus tremuloides and Vicia faba exposed to contrasting light environments under field conditions to evaluate UV acclimation potentials and regulatory roles of photosynthetically active radiation (PAR) and UV in UV-shielding. Within a natural canopy of P. tremuloides, TUV ranged from 4 to 98% and showed a strong nonlinear relationship with mid-day horizontal fluxes of PAR [photon flux density (PFD) = 6-1830 µmol m⁻² s⁻¹]; similar patterns were found for V. faba leaves that developed under a comparable PFD range. A series of field transfer experiments using neutral-density shade cloth and UV blocking/transmitting films indicated that PAR influenced TUV during leaf development to a greater degree than UV, and shade leaves of both species increased their UV-shielding when exposed to full sun; however, this required the presence of UV, with both UV-A and UV-B required for full acclimation. TUV of sun leaves of both species was largely unresponsive to shade either with or without UV. In most, but not all cases, changes in TUV were associated with alterations in the concentration of whole-leaf UV-absorbing compounds. These results suggest that, (1) moderate-to-high levels of PAR alone during leaf development can induce substantial UV-protection in field-grown plants, (2) mature shade leaves have the potential to adjust their UV-shielding which may reduce the detrimental effects of UV that could occur following sudden exposures to high light and (3) under field conditions, PAR and UV play different roles in regulating UV-shielding during and after leaf development.

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Photoprotection, photosynthesis and growth of tropical tree seedlings under near-ambient and strongly reduced solar ultraviolet-B radiation

Cited by 16 publications

References 58 publications

Solar UV‐B effects on PSII performance in Betula nana are influenced by PAR level and reduced by EDU: results of a 3‐year experiment in the High Arctic

Solar UV‐B effects on PSII performance in Betula nana are influenced by PAR level and reduced by EDU: results of a 3‐year experiment in the High Arctic

Seedling growth responses to soil resources in the understory of a wet tropical forest

Adjustments in epidermal UV‐transmittance of leaves in sun‐shade transitions

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