Monitoring uptake and contents of Mg, Ca and K in Norway spruce as influenced by pH and Al, using microprobe analysis and stable isotope labelling

Abstract

In a model system using intact spruce trees (Picea abies [L.] Karst.) we followed the path of magnesium, calcium and potassium during uptake into the root and during long-range transport into the shoot, by multiple stable isotope labelling. The roots of two-and three-year-old spruce trees originating from soil culture were removed from the soil and, in part or in toto, exposed to labelling solutions containing the stable isotopes 25Mg or 26Mg, 41K and 42Ca or 44Ca. Optical-emission-spectroscopy (ICP-OES) of plant fractions and labelling solutions was combined with the quantitative analysis of stable isotope ratios in sections of shock frozen, cryosubstituted material using the laser-microprobe-mass-analyser (LAMMA). This combination allowed us to distinguish, both in bulk samples and on the cellular level between (i) the fraction of elements originally present in the plant before the start of the labelling, (ii) the material taken up from the labelling solution into the plant and (iii) any material released by the plant into the labelling solution.In single-root labelling experiments, roots of three-year-old spruce trees, grown in nursery soil, were exposed to various pH conditions. The exchange of Mg and Ca with the labelling solution was nearly 100% in the cell walls of the mycorrhized finest roots. This exchange was only slightly affected by a step down to pH 3.5. The absolute Mg and Ca content in the cell walls was moderately reduced by incubation at pH 3.5 and strongly reduced in the presence of A1 at this pH. After a pH 3.5 and 2 mM AI treatment we found AI in the xylem cell walls and the cortex cell lumina at elevated concentrations. To analyse the combined effect of high AI and high proton concentrations on the long-range transport, we used a "split-root system". The root mass of an intact two-year-old spruce tree, grown in mineral soil, was divided into even parts and both halves incubated in solutions with two sets of different stable isotopes of Mg and Ca (side A: no A1, 25Mg and 42Ca; side B: +A1, 26Mg and 44Ca) and 41K on both sides. We observed a large uptake of Mg, Ca and K into the plant and a pronounced release. The net uptake of all three elements was lower from the Al-doted solution. In cross-sections of the apical shoot we found after a seven-day labelling period about 60-70% of the Mg and Ca and 30% of the K content in the xylem cell walls originating from both labelling solutions. The clear majority of the Mg and Ca label originated from the Al-doted side.

Capacidade de absorção de nutrientes do capim-mMarandu (Brachiaria brizantha) e da planta daninha malva (Urena lobata) em função do pH

“…Tabela 1 -Equações de regressão polinomial para os diferentes fatores analisados, em função do pH da solução nutritiva Em solos ácidos, os altos níveis de alumínio ou manganês e a deficiência de cálcio são, freqüentemente, considerados os principais fatores limitantes do crescimento das plantas (Balsberg-Pahlson, 1995;Kuhn et al, 1995;Van Raij, 1989), embora a toxidez de ferro possa, também, ser considerada (Sanchez & Salinas, 1982). Neste trabalho, os efeitos deletérios do alumínio podem ser desconsiderados, visto que a solução nutritiva utilizada não apresentava este elemento na sua composição.…”

The history and possible causes of forest decline in central Europe, with particular attention to the German situation

“…Norway spruce and European beech differ greatly in their tolerance to proton and A1 stress. At pH 3.5, the presence of A1 strongly reduces the Ca and Mg content in the cell walls of mycorrhized finest roots of Norway spruce (Kuhn et al 1995). At pH 3.5, the presence of A1 strongly reduces the Ca and Mg content in the cell walls of mycorrhized finest roots of Norway spruce (Kuhn et al 1995).…”

Biological and Chemical Wood Properties of Long-Term Polluted Spruce (Picea abies [L.] Karst.) at High-Altitude Stands of the Erzgebirge

“…Within a tree-ring, the lignin content of tracheids showed a regular distinct intraannual variation (Takano et al 1983;Terashima et al 1986). The restricted K-supply of the trees due to anthropogenic actions in high altitude forest stands of the east ore-mountains is already described by Nebe et al (1995) and Kühn et al (1995). Fergus et al 1969;Takabe et al 1989).…”