Einfluss assoziativer rhizosphärenbakterien auf die äHrstoffaufnahme und den Ertrag von Mais

In mehrjährigen Feldversuchen (1990–1995) in Nordostdeutschland wurde der Einfluß selektierter assoziativer Rhizosphärenbakterien auf den Ertrag und die Nährstoffaufnahme bei Mais untersucht.

Der Trockenmasse‐ und Kolbenertrag zur Siloreife bzw. der Samenertrag wurde durch die Bakterienstämme Pseudomonas fluorescens (PsIA12), Agrobacterium rhizogenes (A1A4), Rhizobium trifolii (R39) und z.T. durch Stenotrophomonas maltophilia (PsIB2) in den Jahren 1990 bis 1995 auf lehmigen Sandböden wiederholt signifikant, auf sandigem Lehm zum Teil signifikant erhöht. Maissorten können unterschiedlich auf die Bakterieninokulation reagieren. Die Bakterien stimulierten insbesondere bei Jungpflanzen die Wurzelentwicklung und die Nährstoffaufnahme (N, P, K) aus dem Boden. Sie bildeten Phytohormone (Auxine und z.T. Cytokinine) und überlebten, auch unter Feldbedingungen, im Rhizosphärenraum von Mais während der gesamten Vegetation.     

Economic utility of 3D remote sensing data for estimation of site index in Nordic commercial forest inventories: a comparison of airborne laser scanning,digital aerial photogrammetry and conventional practices

ABSTRACT

Forest productivity is a crucial variable in forest planning, usually expressed as site index (SI). In Nordic commercial forest inventories, SI is commonly estimated by a combination of aerial image interpretation, field assessment and information obtained from previous inventories. Airborne laser scanning (ALS) and digital aerial photogrammetry (DAP) data can alternatively be used for SI estimation, however the economic utilities of the inventory methods have not been compared. We compared seven methods of SI estimation in a cost-plus-loss analysis, by which we added the expected economic losses due to sub-optimal treatment decisions to the inventory costs. The methods comprised direct and indirect estimation from combinations of ALS, DAP and stand register data, and manual interpretation from aerial imagery supported by field assessment and information from previous inventories (conventional practices). The choice of method had great impact on both the accuracy and the economic value of the produced estimates. Direct methods using bitemporal ALS and DAP data gave the best accuracy and the smallest total cost. DAP was a suitable and low-cost data source for SI estimation. Estimation from single-date ALS and DAP data and age obtained from the stand register provided practical alternatives when applied to even-aged stands.     

The reproductive success of a Quercus petraea × Q. robur F1-hybrid in back-crossing situations

A 56 year old Quercus petraea × Q. robur F1-hybrid was back-crossed to both parental species. Pollen mixes were applied and paternity assigned to offspring based on microsatellite markers. The studied Q. petraea × Q. robur hybrid proved highly fertile and back-crossed well with both Q. robur and Q. petraea with slight but not significant preference for Q. robur. The results do not support the hypothesis about highly unidirectional gene flow between Q. robur and Q. petraea towards Q. robur as the observed back-crossing ability of the hybrid opens a route for nuclear gene flow from Q. robur to Q. petraea. However, Q. petraea × Q. robur hybrids may be rare in nature and the results do not tell us if the (probably more common) reciprocal hybrid also back-crosses easily to Q. petraea.     

The effects of temporal differences between map and ground data on map-assisted estimates of forest area and biomass

Key message

When areas of interest experience little change, remote sensing-based maps whose dates deviate from ground data can still substantially enhance precision. However, when change is substantial, deviations in dates reduce the utility of such maps for this purpose.

Context

Remote sensing-based maps are well-established as means of increasing the precision of estimates of forest inventory parameters. The general practice is to use maps whose dates correspond closely to the dates of ground data. However, as national forest inventories move to continuous inventories, deviations between map and ground data dates increase.

Aims

The aim was to assess the degree to which remote sensing-based maps can be used to increase the precision of estimates despite differences between map and ground data dates.

Methods

For study areas in the USA and Norway, maps were constructed for each of two dates, and model-assisted regression estimators were used to estimate inventory parameters using ground data whose dates differed by as much as 11 years from the map dates.

Results

For the Minnesota study area that had little change, 7-year differences in dates had little effect on the precision of estimates of proportion forest area. For the Norwegian study area that experienced considerable change, 11-year differences in dates had a detrimental effect on the precision of estimates of mean biomass per unit area.

Conclusions

The effects of differences in map and ground data dates were less important than temporal change in the study area.

     

Comparison of chitosans with different molecular weights as possible wood preservatives

Fungi cause serious problems in wood utilization, and environmentally benign wood protection is required as an alternative to traditional chemicals. Chitosan has shown promising antimicrobial properties against several microorganisms. In this study, we present the characterization of and antifungal properties of a commercial chitosan formulation developed for impregnation of wood. A broad range of chemical and mycological methods were used to evaluate the uptake, fixation, and antifungal properties of chitosan for wood preservation. The results show that the higher the uptake of chitosan the lower the relative recovery of chitosan in wood after leaching, and the higher the molecular weight of chitosan the higher the recovery. Chitosan with high molecular weight proved to be more efficient against decay fungi than chitosan with low molecular weight. The fungi tested on chitosan-amended nutrient agar medium were totally inhibited at 1% (w/v) concentration. In decay studies using small wood blocks, 4.8% (w/v) chitosan concentration gave the best protection against brown rot fungi.     

Phylogenetic analysis of the SSU rRNA gene from the piscine diplomonad Spironucleus torosus (Diplomonadida: Hexamitinae)

Previous studies have recorded Spironucleus torosus Poynton et Morrison, 1990 from several species of gadoid fishes, including the only freshwater gadoid, the burbot Lota lota (L.). Two morphologically different isolates of S. torosus have been described (elongate and pyriform). Both have been found in saltwater, while only the elongate has been found in freshwater. To address the conspecificity of the two morphs of S. torosus, and to identify the source of S. torosus in burbot in Norway, we have sequenced the small subunit ribosomal RNA (SSU rRNA) gene from 43 isolates of S. torosus from six species of gadoid fishes sampled at 15 localities in Norway, Sweden and the Baltic Sea. Phylogenetic analyses of the SSU rRNA gene sequence data recovered two major clades, one containing mainly isolates from burbot, while the other contained isolates from marine gadoid fishes only. The genetic distance (based on 25 nucleotide substitutions in 789 base pairs) separating the two assemblages was not large enough to consider the two groups separate species. Spironucleus torosus isolated from burbot displayed limited genetic variation in the small subunit ribosomal RNA (SSU rRNA) gene along the post-Pleistocene migration route of its host. The present study is the first report of S. torosus in tusk Brosme brosme (Ascanius), whiting Merlangius merlangus (L.), and fourbeard rockling Enchelyopus cimbrius (L.).