Báo cáo khoa học: Distribution and variations of potassium and calcium in different cross sections of Picea abies Karst needles and Fagus sylvatica (L) leaves exposed to ozone and mild water stress

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Báo cáo khoa học: "Distribution and variations of potassium and calcium in different cross sections of Picea abies Karst needles and Fagus sylvatica (L) leaves exposed to ozone and mild water stress" article Original Distribution and variations of potassium andcalcium in different cross sections of Picea abies (L) Karst needles and Fagus sylvatica (L) leaves exposed to ozone and mild water stress D Le Thiec M Dixon JP Garrec centre de recherches forestières de Nancy, unité écophysiologie forestière, INRA, 54280 Champenoux, France équipe pollution atmosphérique, (Received 8 September 1994; accepted 28 November 1994)Summary — Two clones of 8-year-old Norway spruce trees, and beech trees, planted directly into thesoil inopen-top chambers, were exposed to elevated ozone concentrations and subjected to a mild soildrought stress. The nutrient partitioning and intertreatment differences in nutrient levels were studied.In elevated ozone, both clones had increased potassium and calcium levels, whereas in beech, ozone-treated trees had decreased potassium levels. Drought caused decreases in these nutrients for allspecies. The effect of combining the 2 stresses was more complex, however, and the previouslyobserved effects were not obtained in all cell tissues. Furthermore, they showed both interspecificand interclonal differences. The hypothesis that ozone affects the root nutrition and cell membrane per-meability is discussed. / water stress / potassium / calcium / cell tissuesozoneRésumé — Répartition et variations du potassium et du calcium dans différentes coupes trans-versales d’aiguilles de Picea abies (L) Karst et de feuilles de Fagus sylvatica (L) soumis à del’ozone et à une sécheresse modérée. Deux clones d’épicéas âgés de 8 ans et des hêtres ont étéplantés directement dans le sol dans des chambres à ciel ouvert ; ils ont été soumis à des concentrationsélevées d’ozone et à un stress hydrique modéré. Les variations et la répartition des éléments minérauxont été étudiées. Les teneurs en potassium et calcium chez les 2 clones augmentent dans les traite-ments de fumigation ; en revanche chez le hêtre les teneurs en potassium diminuent. La sécheresseappliquée fait diminuer ces teneurs pour tous les arbres. L’application combinée de ces 2 stress est pluscomplexe et les observations faites auparavant ne se retrouvent pas dans tous les compartimentsfoliaires et sont différentes entre clones et espèces. L’hypothèse que l’ozone affecte la nutrition miné-rale racinaire et la perméabilité membranaire des cellules est discutée.ozone / sécheresse / potassium / calcium / compartiment cellulaireINTRODUCTION To better study the interactive effects of ozone and drought stress, an experi- ment was conducted on 2 tree speciesAtmospheric pollution (especially ozone) (Picea abies and Fagus sylvatica) plantedhas often been cited as a possible contrib- directly into the soil, enclosed in open-toputory factor in forest decline. Furthermore, chambers and exposed to a soil drying.there is evidence to suggest that current Studies on nutrient distribution at the cel-levels of tropospheric ozone can cause lular level are rare and have never beendamage to trees (Dobson et al, 1990) and performed on trees exposed to both real-ozone levels in Europe and North America istic ozone concentrations and drought,are predicted to rise as emissions of their although some work has been done onprecursors increase in association with declining spruce trees (Stelzer et al, 1990;increased motor traffic. Much work has thus Fink, 1991 a,b; Garrec et al, 1991; Godde etbeen carried out to assess the biochemi- al, 1991).The aim of our study was thuscal and physiological response of trees to to determine foliar nutrient changes inthis pollutant, but the result ...