Stefanescu C, Peñuelas J, Sardans J, Filellla I (2006) Females of the specialist butterfly Euphydryas aurinia (Lepidoptera: Nymphalinae: Melitaeini) select the greenest leaves of Lonicera implexa (Caprifoliaceae) for oviposition. European Journal of Entomology 103: 569-574
Filella I., Peñuelas J. (2006) Daily, weekly, and seasonal time courses of VOC concentrations in a semi-urban area near Barcelona. Atmospheric Environment. 40: 7752-7769.EnllaçDoi: 10.1016/j.atmosenv.2006.08.002
In order to study the daily, weekly, and seasonal patterns and possible origins of air concentrations of volatile organic compounds (VOCs), measurements were taken on a minute-by-minute basis with a PTR-MS in the vicinity of a highway in a semi-urban site near Barcelona. Four periods of the year were chosen and samples were taken under different meteorological conditions and at different phenological stages of the surrounding vegetation. None of the measured VOCs concentrations exceeded air-quality guidelines. The results showed that diurnal, weekly, and seasonal fluctuations in measured VOC concentrations depended on variations in the strength of sources, as well as on photochemical activity and meteorological conditions. There was a decrease in concentrations in most VOCs when mixing depth, photochemical destruction, and wind speed increased at midday. On the other hand, high values of some VOCs occurred at night when the strength of their sinks and the mixing layer decreased. Interestingly, in June, night emissions and concentration peaks of methanol and acetone occurred in periods with dew formation and no wind. VOCs related to anthropogenic emissions presented a weekly pattern of variation with a clear distinction being found between working days and the weekend. The seasonal variation showed higher levels in December for all VOCs, except for isoprene. The thinning of the mixing layer leading to greater concentrations of volatiles and lower wind speeds in winter could account for those higher VOC levels. Benzene and toluene originated mainly from anthropogenic emissions. The sources of acetaldehyde, methanol, and acetone appeared to be mainly biogenic and these compounds were the most abundant of all the measured VOCs. Isoprene concentration patterns suggest a predominantly anthropogenic origin in December and March and a mainly biogenic origin in June and October. All these data provide useful information on the dynamics of VOCs in an area where ozone levels in summer exceed quite often the standard protection thresholds for O3. © 2006 Elsevier Ltd. All rights reserved.
Filella I., Peñuelas J. (2006) Daily, weekly and seasonal relationships among VOCs, NOx and O3in a semi-urban area near Barcelona. Journal of Atmospheric Chemistry. 54: 189-201.EnllaçDoi: 10.1007/s10874-006-9032-z
Daily, weekly, and seasonal patterns of O3, NOx and VOCs and their relationship to meteorological conditions were studied in a semi-urban site near Barcelona by means of five-day long campaigns that included weekend and labor days in December, March, June, and October. The plant protection thresholds for ozone and NO2 were exceeded, respectively, on all the studied days in summer and on all the studied days. Ozone formation was predominantly local and relied on photochemical processes with VOCs playing a controlling role. Formaldehyde, acetaldehyde, methanol, toluene, isoprene, and acetone (in this order) presented the highest O3 formation potential during the studied periods. These results highlight the important role in O3 formation played by VOC species such as acetaldehyde, methanol, and acetone, that all have a significant biogenic component. Thus, these VOCs must be taken into account in the discussion of any ozone abatement strategy. © Springer Science+Business Media, B.V. 2006.
Filella I., Peñuelas J., Llusià J. (2006) Dynamics of the enhanced emissions of monoterpenes and methyl salicylate, and decreased uptake of formaldehyde, by Quercus ilex leaves after application of jasmonic acid. New Phytologist. 169: 135-144.EnllaçDoi: 10.1111/j.1469-8137.2005.01570.x
• Jasmonic acid (JA) is a signalling compound with a key role in both stress and development in plants, and is reported to elicit the emission of volatile organic compounds (VOCs). Here we studied the dynamics of such emissions and the linkage with photosynthetic rates and stomatal conductance. • We sprayed JA on leaves of the Mediterranean tree species Quercus ilex and measured the photosynthetic rates, stomatal conductances, and emissions and uptake of VOCs using proton transfer reaction mass spectrometry and gas chromatography after a dark-light transition. • Jasmonic acid treatment delayed the induction of photosynthesis and stomatal conductance by approx. 20 min, and decreased them 24 h after spraying. Indications were found of both stomatal and nonstomatal limitations of photosynthesis. Monoterpene emissions were enhanced (20-30%) after JA spraying. Jasmonic acid also increased methyl salicylate (MeSa) emissions (more than twofold) 1 h after treatment, although after 24 h this effect had disappeared. Formaldehyde foliar uptake decreased significantly 24 h after JA treatment. • Both biotic and abiotic stresses can thus affect plant VOC emissions through their strong impact on JA levels. Jasmonic acid-mediated increases in monoterpene and MeSa emissions might have a protective role when confronting biotic and abiotic stresses. © New Phytologist (2005).
Inoue Y., Peñuelas J. (2006) Relationship between light use efficiency and photochemical reflectance index in soybean leaves as affected by soil water content. International Journal of Remote Sensing. 27: 5109-5114.EnllaçDoi: 10.1080/01431160500373039
Photosynthetic light response curves and reflectance spectra (380-2500 nm) were measured for soybean (Glycine max L. Merr.) leaves with a range of chlorophyll concentrations at various soil water contents. Regression lines for the relationship between the photosynthetic light use efficiency (LUEp) and photochemical reflectance index (PRI) under different soil water content θ almost all passed through a common point (PRI, LUEp) = (-0.04, 0), so that the LUEp could be expressed simply as LUEp = kAPRI using an adjusted PRI [APRI = (ρ531-ρ570)/(ρ531-ρ570)+0.04]. The effect of soil moisture was strong under dry conditions and gradually decreased with increasing θ. There was no effect of θ above 25% (v/v). The effect of θ on the APRI-LUEp relationship was expressed by a simple exponential function. These results should provide a new basis for applications in dynamic diagnosis of photosynthetic functioning of plant leaves and in the prediction of plant productivity. The change in the slope of LUE vs. APRI may provide further ways of assessing volumetric soil water content.
Peñuelas J (2006) El avance de la primavera y las asincronias entre especies llegan también a España. Temas Investigación y Ciencia (Cambio climático) 45: 78-79.
Jump AS, Hunt JM, Peñuelas J (2006) Rapid climate change-related growth decline at the southern range edge of Fagus sylvatica. Global Change Biology 12: 2163-2174
Inoue Y, Peñuelas J, Miyata A, Mano M (2006) Relationship of reflectance spectra with light use efficiency and canopy CO2 flux at canopy scale in irrigated rice. Recent advances in quantitative remote sensing. 25-29
Jump A.S., Hunt J.M., Martínez-Izquierdo J.A., Peñuelas J. (2006) Natural selection and climate change: Temperature-linked spatial and temporal trends in gene frequency in Fagus sylvatica. Molecular Ecology. 15: 3469-3480.EnllaçDoi: 10.1111/j.1365-294X.2006.03027.x
Rapid increases in global temperature are likely to impose strong directional selection on many plant populations, which must therefore adapt if they are to survive. Within populations, microgeographic genetic differentiation of individuals with respect to climate suggests that some populations may adapt to changing temperatures in the short-term through rapid changes in gene frequency. We used a genome scan to identify temperature-related adaptive differentiation of individuals of the tree species Fagus sylvatica. By combining molecular marker and dendrochronological data we assessed spatial and temporal variation in gene frequency at the locus identified as being under selection. We show that gene frequency at this locus varies predictably with temperature. The probability of the presence of the dominant marker allele shows a declining trend over the latter half of the 20th century, in parallel with rising temperatures in the region. Our results show that F. sylvatica populations may show some capacity for an in situ adaptive response to climate change. However as reported ongoing distributional changes demonstrate, this response is not enough to allow all populations of this species to persist in all of their current locations. © 2006 The Authors.
Klumpp A., Ansel W., Klumpp G., Calatayud V., Garrec J.P., He S., Peñuelas J., Ribas À., Ro-Poulsen H., Rasmussen S., Sanz M.J., Vergne P. (2006) Tradescantia micronucleus test indicates genotoxic potential of traffic emissions in European cities. Environmental Pollution. 139: 515-522.EnllaçDoi: 10.1016/j.envpol.2005.05.021
Urban atmospheres contain complex mixtures of air pollutants including mutagenic and carcinogenic substances such as benzene, diesel soot, heavy metals and polycyclic aromatic hydrocarbons. In the frame of a European network for the assessment of air quality by the use of bioindicator plants, the Tradescantia micronucleus (Trad-MCN) test was applied to examine the genotoxicity of urban air pollution. Cuttings of Tradescantia clone #4430 were exposed to ambient air at 65 monitoring sites in 10 conurbations employing a standardised methodology. The tests revealed an elevated genotoxic potential mainly at those urban sites which were exposed to severe car traffic emissions. This bioassay proved to be a suitable tool to detect local 'hot spots' of mutagenic air pollution in urban areas. For its use in routine monitoring programmes, however, further standardisation of cultivation and exposure techniques is recommended in order to reduce the variability of results due to varying environmental conditions. © 2005 Elsevier Ltd. All rights reserved.
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