Soluble organic nitrogen in temperate forest soils

Very few studies have been related to soluble organic nitrogen (SON) in forest soils. However, this nitrogen pool could be a sensitive indicator to evaluate the soil nitrogen status. The current study was conducted in temperate forests of Thuringia, Germany, where soils had SON (extracted in 0.5 M K₂SO₄) varying from 0.3 to 2.2% of total N, which was about one-third of the soil microbial biomass N by CFE. SON in study soils were positively correlated to microbial biomass N and soil total N. Multiple regression analysis also showed that mineral N negatively affected SON pool. The dynamics of the SON was significantly affected by mineralization and immobilization. During the 2 months of aerobic incubation, the SON were significantly correlated with net N mineralization and microbial biomass N. SON extracted by two different salt solution (i.e. 1 M KCl and 0.5 M K₂SO₄₎ were highly correlated. In mineral soil, SON concentrations extracted by 1 M KCl and 0.5 M K₂SO₄ solutions were similar. In contrast, in organic soil layer the amount of KCl-extractable SON was about 1.2-1.4 times higher than the K₂SO₄-extractable SON. Further studies such as the differences of organic N form and pool size between SON and dissolved organic N (DON) are recommended.     

Influence of measuring angle,nitrogen fertilization,and variety on spectral reflectance of winter oilseed rape canopies

A field experiment with winter oilseed rape was conducted near Göttingen (northern Germany) in the growing season 1998–99. Twelve varieties were compared at two nitrogen (N) application rates (0, 206 kg N ha^–1) regarding shoot dry matter production, shoot N content, shoot N uptake (beginning of shooting, beginning of flowering), and seed yield. Canopy reflectance was measured one week before the beginning of shooting and one week before flowering at different wavelengths between 550 and 940 nm using a spectral reflectance sensor, type FAL II. The vegetation indices red edge inflection point (RIP), soil adjusted vegetation index (SAVI), and normalized vegetation index (NDVI) introduced in literature as indicators of growth parameters were calculated from the reflectance values and compared with growth parameters. The results showed that the measuring angle (–45° to 45°) had a significant influence on the calculated vegetation indices. Therefore, the measuring angle should be kept constant during the measurements. Nitrogen fertilization led to an increase of all vegetation indices. The results revealed significant differences between the tested varieties, indicating problems regarding an accurate estimation of the N status of the crop. Consistent differences in the vegetation indices appeared between varieties with extremely different growth parameters. However, no general relationship between growth parameters and vegetation indices of the 12 varieties could be found. Therefore, variety‐specific calibrations are necessary. The indices RIP and SAVI resulted in similar statements and seem to be good parameters regarding N effects and variety differences, whereas NDVI could resolve variety differences in the fertilized treatments only imperfectly.     

Masked mycotoxins: determination of a deoxynivalenol glucoside in artificially and naturally contaminated wheat by liquid chromatography-tandem mass spectrometry

Conjugated mycotoxins, in which the toxin is usually bound to a more polar substance like glucose, are referred to as masked mycotoxins, as these substances escape routine detection methods but can release their toxic precursors after hydrolysis. This is the first report on the natural occurrence of a glucoside of deoxynivalenol (DON) in Fusarium-infected wheat and maize. To obtain appropriate standards, we chemically synthesized deoxynivalenol-3-beta-D-glucopyranoside (DON-3-glucoside) and deoxynivalenol-15-beta-D-glucopyranoside (DON-15-glucoside). The synthesis products were characterized by liquid chromatography-tandem mass spectrometry. The DON-glucosides showed different collision-induced dissociation (CID) fragmentation behaviors and could therefore be distinguished. Wheat plants were either treated with DON (n = 52) or with Fusarium spp. (n = 4) at anthesis, and after harvest, wheat ears were analyzed for DON and DON-glucosides. All 56 treated wheat samples contained DON and a DON-glucoside with the same retention time, molecular mass, and CID fragmentation behavior as the synthetic DON-3-glucoside. Moreover, the DON-glucoside was also found in two out of three analyzed naturally DON-contaminated maize and in five out of five naturally contaminated wheat samples, in a range from 4 to 12% of the DON concentration. To further confirm the identity of the DON-glucoside, the compound was isolated from wheat extracts and characterized as DON-3-glucoside with NMR. The results of this study indicate the importance to consider both DON and DON-3-glucoside with regard to food and feed safety.     

Inheritance of the sesquiterpenes longipinenone and hydroxy-longipinenone within the Achillea millefolium complex (Compositae)

Three selfing and 13 crossing experiments between tetraploid individuals of Achillea ceretanica, Achillea collina, Achillea distans ssp.‘styriaca’ Saukel (ined.), and Achillea pratensis (Achillea millefolium complex, Compositae), five F₁ crosses, three backcrosses and one further selfing experiment were carried out in order to study the inheritance of longipinenone (1) and its hydroxyl derivative (2). From these crossings, 1294 plants were studied by qualitative thin layer chromatography. Progenies from parent and F₁ plants without longipinenones (0‐type, ll) uniformly contained none of these two sesquiterpenes. All other crossing experiments showed typical segregation patterns of 0‐type, L‐type (longipinenone (1) without hydroxylongipinenone, L.hh) and H‐type (hydroxy‐longipinenone (2) and occasionally longipinenone, L.H.) in the ratio of 1 : 1 and 1 : 3. According to these results both derivatives are under dominant genetic control regulated by genes L and H, whereby hydroxylation takes place after synthesis of longipinenone (1).     

Inheritance of calyx shape in the genus Origanum (Lamiaceae)

Five different traits responsible for calyx shape within the genus Origanum were found to be determined by five independent genes. The five traits are bell‐shaped vs. tubular‐shaped calyx, angular vs. round teeth on the upper lip, entire vs. denticulate upper lip, fully developed vs. reduced lower lip and entire vs. denticulate lower lip. The simple Mendelian inheritance of most traits for calyx shape could be used to identify hybrids between Origanum species arising from open‐pollinated plants and so avoid tedious artificial pollination resulting from small flower sizes in Origanum. Such hybrids are interesting base material for character transfer (e.g. winter hardiness or seed size) between economically important species.     

Defence responses in plantation‐grown Eucalyptus globulus and Eucalyptus nitens after artificial fungal inoculation

The formation of reaction and barrier zones was studied in the xylem of Eucalyptus globulus and Eucalyptus nitens tree stems after wounding and artificial inoculation with two white rot fungi. The study had two objectives: to describe host responses in Eucalyptus spp. by light microscopy and to determine whether they would differ in a fungal treatment (wounding and inoculation by one of two fungal isolates) when compared to a control treatment (wounding only). Eucalyptus globulus and E. nitens developed similar reaction and barrier zones. The E. globulus barrier zone was characterized by kino vein formation. In both hosts, the reaction zone was primarily influenced by content and distribution of living tracheids and parenchyma cells within the sapwood. By contrast, the anatomy of the barrier zone showed similarities to the basic xylem structure of each host, except for some cell types that were newly formed (sclereids, kino veins) or increased in number (parenchyma cells, tracheids). Other cell types were reduced in number or completely absent. Host response in terms of barrier zone width appeared to be greater in the fungal than control treatment. Both wood decay fungi appeared to induce a wider barrier zone in both species than that associated with non‐specific damage caused exclusively by wounding. However, the small number of replicates available for this study was possibly insufficient to provide statistical evidence for different barrier zone width between fungal and control treatments.     

Analyzing time and fuel consumption in road transport of round wood with an onboard fleet manager

Round wood supply in Austria is often affected by different factors such as bottlenecks or oversupply due to changing market, weather and road conditions. An additional factor impacting the complex wood supply chain is the rising transport costs from the landing to the sawmill. Logging trucks are the primary transportation technology used from the forest to the customer??s site. The objectives of this study were to analyze the actual situation and characteristics of typical trucking activities for round wood supply from the region to an Austrian sawmill. The study used time and fuel consumption, proportion of travel on forest roads and average speed on different functional road classes to estimate productivity and costs. Data collection including GPS-tracking was done using fleet management equipment built into the driver??s cabin. The GPS-routes were analyzed in ArcGIS 9.3 based on the national road network and its attributes. The sawmill studied with a yearly demand of 600,000 m³ round wood was located in southern Austria. In total, more than 2,000 round trips operated by seven logging trucks recorded close to 100,000 km. The transport distance from the forest to the sawmill averaged 51 km. The average share on forest roads within a route to the sawmill was 14.2% with an average speed of 13.5 km/h, whereby the forest road is defined as road with minor importance. Transport costs from the forest site to the sawmill with a truck and trailer were ? 11/m³ solid timber based on an average load size of 25 m³. An average 0.77 l of diesel fuel per kilometer was consumed during a round trip including all work phases. A trip to an interim storage location consumed 2.05 l/km due to the number of work phases without driving distance.     

Microbial biomass and enzyme activities in coniferous forest soils as affected by lignite-derived deposition

A forest ecosystem study was conducted along a deposition gradient of air pollutants in old Scots pine stands located near the industrial belt around the city of Bitterfeld in northeast Germany from 1999 to 2000. In order to estimate the impact of different atmospheric deposition loads on microbial biomass and enzyme activities, samples were taken from the forest floor (L, F, and H horizon) and the mineral topsoil (0–10 cm). The emission-induced increases in ferromagnetic susceptibility, soil pH, concentrations of mobile (NH ₄NO ₃ extractable) Cr and Ni, effective cation exchange capacity, and base saturation in the humus layer along the 25-km long transect reflected that great portions of the past depositions were characterized by alkaline fly ash. Alkaline depositions significantly ( P <0.05) decreased the microbial biomass C and N contents, microbial biomass C-to-organic C ratios, and microbial respiration rates, but increased the metabolic quotient (qCO ₂) of the mineral topsoil and forest floor. Variations in microbial biomass and activity can mainly be predicted ( r ² =0.60) by the concentrations of Ca, Zn and Cd in these forest soils. The specific activities (activity kg ^-1 organic C) of l-asparaginase, l-glutaminase, arylsulfatase, and in part, acid phosphatase were significantly ( P <0.05) higher at forest sites receiving higher fly ash loads than those of the other sites, and thus followed the trend of the qCO ₂. In contrast, the specific activity of ß-glucosidase was significantly ( P <0.05) decreased at heavily affected sites compared to moderate and less affected sites, suggesting an inhibition of C mineralization in the forest floor of pine stands affected by predominantly alkaline emissions. A great portion ( r ²=0.91) of the variation in the specific enzyme activity data in forest soils in emission areas can be predicted from a linear combination of the variables total organic C and NH ₄Cl-extractable Ca, pH and effective cation exchange capacity.