A method for quantifying changes in the epicuticular wax structure of Norway spruce needles

Abstract

A method for quantifying changes in the epicuticular wax structure of spruce needles {Pieea abies) has been developed for the scanning electron microscope. This evaluation system, based on a five-point scale, classifies only the epistomatal waxes of current-year needles. Two criteria, the different crystal wax forms and the amount of changed wax as a percentage of the total stomatal area have been used for classification. Statistically significant results (accuracy below + 10% at 5% error level) were obtained under the following conditions. Mixed needle samples were taken from two adjacent trees per site. These were in a dominant and predominant social position m the stand. The needles were collected from the 7''" whorl of sun crowns exposed to all wind directions. The wax quality was determined by evaluating three stomata per needle. One stoma was investigated at the needle base, one m the middle and the third at the apex of the needle. 24 needles were evaluated per site.SEM-Investigations of needle waxes of 25 Austrian forest sites with no local emission source (background sites) showed, that the mean wax quality ranged from 1.6 to 4.1, according to this classification method. Stepwise multiple regression analyses with site characteristics and element contents of the needles (nutrient elements, heavy metals) confirmed correlations between the wax quality and the manganese-and sulphur-content of the needles and also the average degree of crown defoliation.

Latent manganese deficiency increases transpiration in barley (Hordeum vulgare)

“…In algae ( Euglena gracilis ), the fatty acid composition was changed under Mn deficiency (Constantopoulus 1970), especially a reduction in α‐linolenic acid, which is known to be a principal component of the cuticle in higher plants. Likewise, Trimbacher and Eckmüllner (1997) found a strong correlation between the Mn and S tissue concentration of Norway spruce needles and their wax content, but the relation was not investigated at the biochemical level. However, in combination with the observed slack appearance of Mn‐deficient leaves in this study, probably caused by poor lignification due to reduced PAL activity (Burnell 1988), it seems very likely that Mn deficiency increases the leaf conductance via a reduction in the epicuticular wax content, thereby facilitating the marked increase in transpiration.…”

Plants and Atmospheric Aerosols

“…Apparent wax degradation has been associated with tree damage symptoms, including winter desiccation (Huttunen et al 1981), needle loss (Bruck et al 1989;Mengel et al 1990;Sauter and Voss 1986;Takamatsu et al 2001;Trimbacher and Eckm€ ullner 1997;Turunen and Huttunen 1990), and, notably, increased g min (Anfodillo et al 2002;Cape and Fowler 1981;Heinsoo and Koppel 1998;Sase et al 1998;van Gardingen et al 1991), but a satisfactory mechanism for wax degradation has remained elusive. In some cases, amorphous aerosol deposits following repeated deliquescence and efflorescence (see Figs.…”

Hygroscopic particles on leaves: nutrients or desiccants?

“…Trimbacher and Eckmüllner (1997) classified the form and amount of Picea abies needle waxes from 25 Austrian forest sites with no local emission source (background sites). A correlation of the wax quality with the average degree of crown defoliation, as well as with the manganese and sulfur content of the needles, was found by applying stepwise multiple regression analyses of site characteristics and the element contents of the needles (Trimbacher and Eckmüllner 1997). Again, the results of these regression analyses could be explained by deliquescent hygroscopic particles leading to increased HAS and reduced drought tolerance.…”

“…Although scanning electron microscopy (SEM) can be used to determine particle accumulation (Gu¨nther and Wortmann 1966, Fortmann and Johnson 1984b, Coe and Lindberg 1987, SEM has been used more intensively to examine the structure of leaf surfaces and for taxonomic purposes (e.g., Eglinton and Hamilton 1967, Jeffree et al 1976). It has also been widely applied to describe wax ''degradation'' or ''erosion'' on needle and leaf surfaces in studies related to forest decline (Godzik and Sassen 1978, Huttunen and Laine 1983, Crossley and Fowler 1986, Sauter and Voss 1986, Trimbacher and Eckmu¨llner 1997. Although SEM images enable a compelling view of the complexity and details of surface structures, it has been noted that probably ''in many cases contaminants were misinterpreted as wax granules and vice versa'' .…”

“…However, very few studies have reported a massive loading of leaves with aerosols, and the absence of these studies may be related to the difficulties of detecting deliquescent hygroscopic particles. At the same time, the widespread occurrence of degraded or eroded epicuticular waxes in areas with high air pollution (Crossley and Fowler 1986, Sauter and Voss 1986, Turunen and Huttunen 1990, Gu¨nthardt-Goerg et al 1994, Riederer et al 1994, Bermadinger-Stabentheiner 1995, Trimbacher and Eckmu¨llner 1997, has yet to be comprehensively explained. While degraded waxes have been highly correlated with primary forest decline symptoms, they have not been included in the current explanations of forest declines in Central and Northern Europe, the Eastern United States, and Eastern Asia, which have been mostly attributed to air pollution.…”