1,720,995 research outputs found
The humanized mineral world: towards social and symbolic evaluation of prehistoric technologies in South Eastern Europe. Proceedings of the ESF workshop, Sofia 3-6 September 2003
No full text
Isoprene prevents the negative consequences of high temperature stress in Platanus orientalis leaves
No full textChanges in photosynthesis, mesophyll conductance to CO2, and isoprenoid emissions in Populus nigra plants exposed to excess nickel
No full textLocalized ozone fumigation system for studying ozone effects on photosynthesis, respiration, electron transport rate and isoprene emission in field-grown Mediterranean oak species
No full textIsoprenoid emissions, photosynthesis and mesophyll diffusion conductance in response to blue light
No full textThe effects of blue light (BL) on leaf gas exchange of Populus×canadensis, a strong isoprene emitter, and Quercus ilex and Citrus reticulata, two monoterpene emitters with respectively small and large storage pools for monoterpenes, were studied. Leaves were initially exposed to a saturating photosynthetic photon flux density (PPFD) of white light (WL), which was then progressively reduced to perform WL-response curves. Leaves acclimated to saturating WL were then quickly exposed to equivalent BL levels to perform BL-response curves. Blue light did not significantly affect photosynthetic parameters in the light-limited portion of the PPFD-response curves in both P.×canadensis and Q. ilex. Whereas photosynthesis (A), stomatal conductance (gs), and mesophyll conductance (gm) were significantly decreased at high PPFDs of BL. A was similarly inhibited by BL in C. reticulata, but there was no significant effect of light quality on gs. Overall these results show that the negative effect of BL on photosynthesis is widespread in tree species with different leaf characteristics, and that this involves coordinated reductions in gs and gm. BL negatively affected isoprene emission and, to a lesser extent monoterpene emissions, in concert with photosynthetic inhibition. Interesting, both isoprene and monoterpene emissions were shown to be inversely dependent upon intercellular [CO2]. These results indicate that a change in light spectral quality, which can vary during the day, between days and within seasons, can alter photosynthesis and isoprenoid emissions, depending on the PPFD intensity. Such effects should be strongly considered in photosynthesis and volatile isoprenoid emission models. © 2013 Elsevier B.V
Isoprene emission and primary metabolism in Phragmites australis grown under different phosphorus levels
No full textUltradian variation of isoprene emission, photosynthesis, mesophyll conductance, and optimum temperature sensitivity for isoprene emission in water-stressed Eucalyptus citriodora saplings
No full textWater availability is a major limiting factor on plant growth and productivity. Considering that Eucalyptus spp. are among the few plant species able to produce both isoprene and monoterpenes, experiments were designed to investigate the response of isoprene emission and isoprenoid concentrations in Eucalyptus citriodora saplings exposed to decreasing fraction of transpirable soil water (FTSW). In particular, this study aimed to assess: (a) the kinetic of water stress-induced variations in photosynthesis, isoprene emission, and leaf isoprenoid concentrations during progressive soil water shortage as a function of FTSW; (b) the ultradian control of isoprene emission and photosynthesis under limited soil water availability; and (c) the optimum temperature sensitivity of isoprene emission and photosynthesis under severe water stress. The optimum temperature for isoprene emission did not change under progressive soil water deficit. However, water stress induced a reallocation of carbon through the MEP/DOXP pathway resulting in a qualitative change of the stored isoprenoids. The ultradian trend of isoprene emission was also unaffected under water stress, and a similar ultradian trend of stomatal and mesophyll conductances was also observed, highlighting a tight coordination between diffusion limitations to photosynthesis during water stress. The kinetics of photosynthetic parameters and isoprene emission in response to decreasing FTSW in E. citriodora are strikingly similar to those measured in other plant functional types. These findings may be useful to refine the algorithms employed in process-based models aiming to precisely up-scale carbon assimilation and isoprenoid emissions at regional and global scales
The role of isoprene emission in two Arundineae species exposed to progressive drought stress
No full textIsoprene is the most abundant biogenic volatile organic compound emitted
from vegetation and has been suggested to have protective role in plants under
different kinds of stress. In this study we compared the responses to drought
stress of two Arundineae species which differ in their ability to emit isoprene –
Arundo donax, a promising biofuel crop and isoprene emitter, and Hakonechloa
macra, a non-emitting ornamental plant. Our results showed better recovery
of photosynthesis in A. donax after rehydration in comparison to H. macra.
H. macra had lower photosystem II (PSII) photochemical efficiency, increased
non-photochemical quenching (NPQ) and high levels of leaf malondialdehyde
(MDA) and proline content when exposed to drought stress. The isoprene emitting
species A. donax showed enhanced drought tolerance and better recovery
after rewatering than the non-emitting H. macra. Our results confirm the idea
that in isoprene emitting species, the function of isoprene is closely associated
with functioning of the photosynthetic apparatus
- …
