Environmental and Experimental Botany 59 (2007) 49–58 Effects of Eu and Ca on yield and mineral nutrition of wheat (Triticum aestivum) seedlings Irina Shtangeeva a,∗ , Sophie Ayrault b a St. Petersburg University, Universitetskaya nab., 7/9, St. Petersburg 199034, Russia b Laboratoire des Sciences du Climat et de l’Environnement, CEA-CNRS, 91198 Gif sur Yvette Cedex, France Received 11 May 2005; received in revised form 1 August 2005; accepted 15 October 2005 Abstract Although fertilisers enriched in rare earth elements (REE) are widely used in agricultural practice, little is known yet about behaviour of the REE in soil–plant system. Among REE, europium (Eu) may be of highest interest. Eu may serve as an indicator of biogeochemical processes due to a change of its valence state under different environmental conditions. Since chemical characteristics of Ca and REE are similar, Eu may compete with Ca for organic ligands. In the present work we studied the influence of Eu and Ca on the growth and mineral nutrition of wheat seedlings. An application of Eu favoured germination and root growth, whereas in combination with Ca it produced a more sustained leaf growth. Eu affected uptake and distribution of certain nutrients in different parts of a plant. The content of Eu in all parts of wheat seedlings at the end of germination significantly increased. Transfer of the seedlings germinated in the Eu-rich medium into soil resulted in the release of Eu from the plants. Nevertheless, 9 days after the sowing, Eu concentration in the seedlings was still much higher than in the control plants. © 2005 Elsevier B.V. All rights reserved. Keywords: Europium; Calcium; Rare earth elements; Trace- and macro-elements; Wheat seedlings; Germination 1. Introduction Rare earth elements (REE) are widely distributed in the environment. Despite of the name they are not quite rare in the nature. The abundance of cerium in soil is almost equal to that of copper and zinc. The abundance of the most rare REE, lutecium and thulium in the majority of soils is comparable to that of cadmium and selenium (Tyler, 2004). While REE are abundant in soil, their concentration in plants is usually low (Fu et al., 2001; Zhang et al., 2002; Tyler, 2004). The biogeochemical behaviour of REE in the soil–plant system is not fully understood. Until recently, REE have not been characterized as essential plant nutrients and environmen- tally hazardous metals. It is quite possible that both toxic and beneficial effects of REE are similar to those of other trace metals. ∗ Corresponding author. Tel.: +7 812 3666 122. E-mail address: shtangeeva@mail.ru (I. Shtangeeva). REE have been used in agriculture since the seventies of last century. Particularly in China REE-based fertilisers are widely used to increase the yield and quality of crops (Xiong, 1995; Zhang and Shan, 2001; Xu et al., 2002; Shan et al., 2005). Pot and field experiments have been performed to demonstrate beneficial influence of REE on plant growth and soil properties. Interestingly, beneficial effects of REE on plants and soils have been reported mainly by the Chinese researchers. It was found that REE stimulate the synthesis of chlorophyll (Guo, 1988), promote seedling development (Wu et al., 1983; Chang, 1991), and improve the bioavailability of Ca and Mn in soil (Chang, 1991). Notice however that reported data on field and laboratory tests is often contradictory and inconsistent. For example, Maheswaran et al. (2001) studied the effects of lanthanum (La) and cerium (Ce) on seed germination using various rates ranging from 0 to 0.16%. They reported that both shoot and root lengths were not improving with an application of REE. Application of La or Ce to the shoots or roots gen- erally reduced corn and mungbean growth rate (Diatloff et 0098-8472/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.envexpbot.2005.10.011