Shoot Sr concentrations in relation to shoot Ca concentrations and to soil properties

Abstract

This work was aimed to investigate whether shoot Sr concentrations of plant species are related to respective Ca concentrations and to soil properties and to compare the Sr-Ca observed ratios (OR), defined as the quotient of the ratios Sr/Ca in shoots and in the soil solution or in the extractable form, among species and soils. Ten pasture plant species were grown in pots (1-L volume) filled with eight soils differing in the various physicochemical characteristics. Each pot received 50 mg Sr except those of the soil with the highest cation exchange capacity (C.E.C.) that received 100 mg Sr per pot. For each soil, shoot Sr concentrations of species were linearly and positively related with the respective Ca concentrations. C.E.C, organic matter content and Ca in the soil solution or in the extractable form were the only soil properties that were related, all negatively, with shoot Sr concentrations. The ratio of extractable Sr and Ca was positively and linearly related with the ratio of Sr and Ca. in the soil solution. OR was affected by both species and soils. Most of OR values of all species in all soils ranged between 0.8 and 1.5, except for the grass Agrostis capillaris which had the highest values for most of soils. This indicates that Agrostis capillaris compared to other species, takes up proportionally more Sr than Ca.

Test of soil extractants for their suitability in predicting Ca/Sr ratios in leaves and stems of sugar maple seedlings

“…Therefore Ca is impoverished over Sr along the soil-stem-leaf pathway based on NH 4 EDTA extracts. This is contrary to what has been observed in many studies for the majority of plants, but there are exceptions (Runia 1987;Veresoglou et al 1996;West et al 2001). Both water and NH 4 Cl regressions had slopes smaller than one and discrimination factors for leaves of more than one and, therefore, were more in line with the increasing gradient of Ca/Sr usually observed in the soil plant system (Poszwa et al 2000;Dasch et al 2006).…”

“…Since different species often have different Ca/Sr ratios when growing in the same soil (Runia 1987;Veresoglou et al 1996;West et al 2001), the relationships between soil and plant tissue Ca/Sr are also likely to be species specific. Soil-plant predictive models of Ca/Sr ratios should therefore be determined for other combination of species and extractants in order to improve the applicability of the Ca/Sr ratio approach to assess/locate the source of soil Ca to plants.…”

A phylogenetic effect on strontium concentrations in angiosperms

“…Second, there might also be differences between Sr and Ca because of the fact that the REML process accounts for differences due to species and study but not differences arising from their interaction. Ca:Sr ratios in plants in general reflect Ca:Sr ratios in soil solution (rather than total Ca:Sr in soil), and this ratio can vary significantly with soil type even when the same total amounts are present (Veresoglou et al, 1996). Thus, interactions between soil variables such as Ca:Sr in solution and species rank order would need to be accounted for before concluding definitively that the phylogenetic signals of Ca and Sr are not identical.…”

“…43-49; Veresoglou et al (1995), 2 × 3 treatments. 49-56, Veresoglou et al (1996), 2 × 4 treatments. 57, Andersen (1967).…”

“…Broadley et al (2003) demonstrated the importance that phylogenetic effects in the variation of Ca concentration in angiosperms might have for predicting transfer coefficients and managing human dietary intakes of Ca. Given that Ca and Sr are known to behave similarly during soil-to-plant transfer (Andersen, 1967;Veresoglou et al, 1995Veresoglou et al, , 1996, we hypothesised that there is a phylogenetic effect on Sr concentrations in plants and that this might be useful for predicting transfer coefficients, managing dietary intakes and selecting plants for phytoextraction of 90 Sr. Here, using the same statistical methods as Broadley et al (2003), we report an analysis for 103 taxa we grew and 66 taxa from the literature, that quantifies a phylogenetic effect on Sr content of angiosperms and compares it to that of Ca.…”