The trace and major element composition of the leaves of some deciduous trees

Summary The contents of 21 trace and major constitutents in the leaves or leaf blades of three species of deciduous trees, sycamore, horse-chestnut and beech, have been studied at regular intervals throughout the season. The various elements can be grouped into three categories: (A) Co, Ni, Fe, V, Ti, Cr, Pb and Al, (B) Mn, B, Si, Ca, Sr, Ba, and Mg, and (C) Cu, Mo, Zn, P, K, and Na. The Group-A elements, including most of those whose essentiality has not been established, together with Fe, show a fall in concentration in the leaf early in the season, probably as a result of dilution due to increase in dry weight as the absolute amount per leaf rises slightly, followed by steady rise until senescence, when a further fall occurs. In Group B, in which Si Sr, and Ba are considered non-essential, there is a continual rise both in concentration and absolute content until late in the season. In Group C, all the elements of which, except possibly Na, are essential, there is generally a gradual fall followed by a period when the content remains relatively constant, although Na and Zn, together with Pb from Group A, show an unexpected increase at senescence.Group-A elements show a decrease in concentration with height, which can only partly be explained by dilution due to increase in dry weight with height, while Group-B and -C elements are relatively constant at all heights. Results are also presented for some petioles and inflorescences. There does not appear to be any systematic transfer from leaf to inflorescence at any stage of growth. The only elements whose contents could be used systematically for diagnostic purposes appear to be those in Group C, during the midseason period of constant concentration.