Esperanza Calvo

Responses of evergreen and deciduous Quercus species to enhanced ozone levels

Plants of one evergreen oak (Quercus ilex) and three deciduous oaks (Q. faginea, with small leaves; Q. pyrenaica and Q. robur, with large leaves) were exposed both to filtered air and to enhanced ozone levels in Open-Top Chambers. Q. faginea and Q. pyrenaica were studied for the first time. Based on visible injury, gas exchange, chlorophyll content and biomass responses, Q. pyrenaica was the most sensitive species, and Q. ilex was the most tolerant, followed by Q. faginea. Functional leaf traits of the species were related to differences in sensitivity, while accumulated ozone flux via stomata (POD1.6) partly contributed to the observed differences. For risk assessment of Mediterranean vegetation, the diversity of responses detected in this study should be taken into account, applying appropriate critical levels.

Spatial pattern of ozone injury in Aleppo pine related to air pollution dynamics in a coastal–mountain region of eastern Spain

In eastern Spain, studies combining the tracking and meso-scale circulations of air pollutants with the evaluation of their effects on plants have been undertaken since 1994. Meso-scale processes are very important from the point of view of how and where forest ecosystems are affected by point sources and regional air pollution in the Mediterranean area. The first results of these field surveys show that in 1994, 1995 and 1996, the distribution pattern of ozone visual injury (chlorotic mottle) in Pinus halepensis correlated with the penetration of pollutants transported by the sea-breeze into coastal valleys of Castellón (eastern Spain). In this tree species, longer needles are associated with higher chlorotic mottle, and ozone injury seems to be among the factors affecting needle retention and crown transparency.

Analysis of molecular markers in three different tomato cultivars exposed to ozone stress.

Three differentially expressed cDNAs have been isolated from ozone treated tomato seedlings. Their level of expression after ozone exposure has been analysed in three tomato cultivars with different sensitivity to ozone (Nikita, Alisa Craig and Valenciano). These comparative analyses have been extended to a number of genes involved in antioxidative, wounding or pathogenesis responses, showing several differences among cultivars that could be related with their different sensitivity to ozone. Gene response to ozone was affected not only by the period and dose of ozone exposure (short time or chronic), but also by growth conditions (controlled growth chamber or field). Comparison of gene expression patterns puts on evidence the needing of validation in field of experiments performed with plants grown under controlled conditions. Our results suggest that changes in genes expression, observed after ozone treatment in field, are affected by additional factors related to environmental clues.

Spatial pattern of ozone injury in aleppo pine and air pollution dynamics in the Mediterranean

Abstract Interdisciplinary studies, combining the evaluation of ozone effects with the meso-meteorological interpretation of the ozone data have been carried out in eastern Spain since 1994. Mesoscale circulations are very important from the point of view of how and where forest ecosystems are affected by point sources and regional air pollution in the Mediterranean Area. First results of these field surveys show that during 1994, 95 and 96, ozone visual injury (chlorotic mottle) in Pinus halepensis Mill. was well correlated with the penetration of the sea breeze in coastal valleys of Castellon. Patterns of ozone injury, chlorotic mottle, have been positively correlated with needle-age classes looking at tree level.

Artichoke Cultivars (var. “Blanca de Tudela”) under Elevated Ozone Concentrations

Ozone concentrations rise to phytotoxic levels from spring to autumn at western Mediterranean basin coastal sites, where artichoke is one of the most important crops. Simultaneously, from year to year and especially since the early 1980s, resprouting of the stumps has been decreasing in Valencian Community artichoke plantations. To see if ozone might be playing a role in this decrease, a number of plants were exposed to different levels of ozone. Results of the ozone treatments showed reduced biomass in the offshoots of plants exposed to the highest ozone treatment. The exposure to ambient ozone during the stump-establishment period, when compared to filtered-air conditions, resulted in a reduction in yield when plants were transplanted in the field under ambient ozone concentrations. And when plants were exposed to acute short picks, typical ozone visual injury appeared in the older leaves.