Methods were established, which render possible a simultaneous determination of ri‐bulose‐l,5‐bisphosphate (RuBP) carboxylase (EC 4.1.1.39) activity and chlorophyll content of Norway spruce (Picea abies Karst.) needles from a detergent‐containing aqueous crude extract. Spruce RuBP carboxylase was tentatively characterized with regard to kinetic properties. Recovery experiments employing purified wheat RuBP carboxylase proved quantitative extraction of the enzyme from spruce foliage. Five timber stands consisting of 35–62 years old spruce, two of which exhibited the typical symptoms of recent spruce decline, were compared. For the needle generations 1 to 4 the enzyme activities as well as chlorophyll and protein concentrations were determined. The results do not indicate an involvement of RuBP carboxylase in spruce decline.
Summary. The amount of abscisic acid (ABA) in needles of silver fir from a natural location was investigated with regard to position in the crown, damage, seasonal variation, and needle age. Because of problems of quantification of ABA in coniferous needles, which contain numerous secondary plant products, a method for reliable determination of both isomers cis-trans-ABA (c-ABA) and transtrans-ABA (t-ABA) was developed. By means of gas chromatography (GC) using an electron capture detector (ECD) and a programmed temperature vaporizer (PTV) injector complete separation of both compounds was achieved. Two different pairs of fir were investigated -in each case a damaged and a healthy tree. Needles from both trees from the first and the second pair collected in September contained 500-1100 ng c-ABA/g fresh weight (FW), and the concentrations of t-ABA varied from 400 to 700 ng/g FW. Investigations from the second pair show highest amounts of 2900 ng/g Fw c-ABA and 1800 ng/g FW of t-ABA in May and June. For the first pair a higher c-ABA content was found in needles from the top of the crown than in those from the middle and the base. This difference could not be confirmed in the analysis of the second pair. Because of the strong natural deviation no statistically significant difference between the healthy and the damaged tree was found. The first pair of firs examined showed a higher t-ABA concentration than the second one. In this case the highest amount was found in the top of the crown. Methodical mistakes during the clean-up procedure and in quantification by gas chromatography could be excluded. The presence of c-and t-ABA in the purified extract was corroborated by mass spectrometry. With regard to the seasonal variation both isomers of ABA show an unequivocal trend. The maximum concentration is achieved in May to June, whereas the content is minimal inCorrespondence to: H. Ziegler August/September. In any case the level of t-ABA is lower than that of c-ABA. No correlation between the amount of ABA and the needle age could be established.
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