The effects of nutrient limitation on the response of Plantago major to ozone

Abstract

Most natural and semi-natural communities are limited by major nutrients such as nitrogen (N) or phosphorus (P), but most experiments on the effects of ozone on wild plants have used nutrient-rich composts or soil. In order to investigate interactions between ozone and low nutrient supply, two artificially selected lines (ozone-resistant and ozone-sensitive) of two populations Plantago major ssp. major L. were grown on a sandy loam, with (HN) and without (LN) addition of fertilizer. The soil was from a semi-natural grassland that has never been fertilized. Plants were exposed to either charcoal\Purafil2-filtered air (CF l 5 nl O $ l −" ) or 70 nl O $ 1 −" 7 h d −" from the seedling stage to seed production.Poor growth (c. 25 % of that in HN) of the low-nutrient plants, and leaf concentrations of N and P showed that the LN plants were severely nutrient-limited. In addition to affecting the total dry mass of the plants, the nutrient supply altered seed production, reproductive effort (number of seeds per total mass) and root-to-shoot allocation. Exposure to ozone had significant effects on physiology, growth, and seed production that varied with population, selection line, time, and plant development. There also were significant interactions between ozone effects and nutrient regime. In the Lullington Heath population, ozone reduced plant dry weight at 4 wk only in the LN treatment, and in the sensitive line of the Bush population, seed production was reduced by ozone only in LN. Therefore, contrary to what was expected, in the present experiment, plants given the LN treatment were often more sensitive to ozone than those grown under the high-nutrient regime. This increase in sensitivity was despite the fact that the LN treatment reduced stomatal conductance and ozone flux. It is concluded that there are potentially important interactions between ozone and low nutrient supply that need further investigation, particularly under field conditions.

Kinetics of nutrient uptake by roots: responses to global change

“…As the main organ involved in water and nutrient uptake and as one of the major sinks for assimilated C, roots play a critical role in determining plant and ecosystem responses to various facets of global change ranging from N deposition and elevated CO # (Norby, 1998 ;Van Noordwijk et al, 1998) to elevated ozone and UV-B (Pell et al, 1995 ;Klironomos & Allen, 1995 ;Rennenberg et al, 1996 ;Scagel & Andersen, 1997 ;Whitfield et al, 1998). Despite the growing recognition that roots play a critical role in determining the overall response of terrestrial vegetation to global change, very little is known about the mechanisms involved.…”

Effects of combined ozone and nitrogen deposition on the in situ properties of eleven key plant species of a subalpine pasture

“…Consequently, as a result of phenotypic plasticity, O 3 tolerance could be modulated by N availability: plants might become less tolerant to O 3 stress when RGR is stimulated by higher N availability or, alternatively, more tolerant when detoxiWcation is increased through N stimulation of A. In Plantago major, high nutrient supply protected individuals from O 3 damage (WhitWeld et al 1998). So far, at the level of intact plant communities, interactions between O 3 exposure and N input have not been tested.…”

Protective effect of Mn(III)–desferrioxamine B upon oxidative stress caused by ozone and acid rain in the Brazilian soybean cultivar Glycine max “Sambaiba”

“…Conversely, ozone did not alter the TBARS content upon MnDFB treatment (Table 2), indicating that MnDFB prevented oxidative damaged by ozone. The protective effect of MnDFB on soybean plants could be related to an increase of Mn in soil, which can limit the effect of ozone (Whitfield et al 1998). However, metal contents in leaves and roots were not changed in MnDFB-treated plants upon ozone treatment, suggesting that the metal homeostasis was undisturbed, possibly with no ROS excess production triggered by the metal delivered to the leaves (Izaguirre-Mayoral and Sinclair 2005).…”