Finding suitable growth models for turbot (Scophthalmus maximus L.) in aquaculture 1 (length application)

Growth data of two different commercial turbot (Scophthalmus maximus) strains reared in recirculating aquaculture systems were analysed with the aim to determine the most suitable model for turbot. To assess the model performance three different criteria were used: (1) The mean percentage deviation between the estimated length and actual length; (2) the residual standard error with corresponding degrees of freedom and (3) the Akaike information criterion. The analyses were carried out for each strain separately, for sexes within strains and for a pooled data set containing both strains and sexes. We tested a pre‐selection of six models, containing three to four parameters. Models were of monomolecular shape or sigmoid shape with a flexible point of inflection including the special case of monomolecular shape in defined cases of their parameters. The 4‐parametric Schnute model achieved best fit in 62% of all cases and criteria tested, followed by the also 4‐parametric generalized Michaelis–Menten equation in 48% and the 4‐parametric Janoschek model (38%). The von Bertalanffy growth function achieved only 29%, Brody 24% and a new flexible function 19% best fit. In a 1–1000 day growth‐simulation sigmoid shaped curves were produced by the Schnute model in 71% of cases. The Janoschek and the Michaelis–Menten model each produced sigmoid curves in 57% of all cases. This indicates that a flexible 4‐parametric function reflects the growth curve of turbot the best and that this curve is rather sigmoid than monomolecular shaped.     

体重决定猪回肠内的蛋白吸收率

<正>近期伊利诺伊大学的J.A.Almeida博士、 Hans H.Stein博士以及Carsten Pedersen博士联手展开体重对于标准化回肠蛋白质和氨基酸吸收率的影响试验,结论证明,20 kg以下的仔猪回肠对于粗蛋白和氨基酸的吸收率比20~50 kg的育成猪和50~110 kg的育肥猪低。而且同一猪群的不同猪只也表现出吸收率的差异性。例如,在测定的300只仔猪中粗蛋白和氨基酸的吸收率     

Wood modification with alkoxysilanes

Wood was treated with three different alkoxysilanes which are able to undergo a sol–gel process: tetraethoxysilane (TEOS), methyl triethoxysilane (MTES) and propyl triethoxysilane (PTEO). Two types of treatments were compared: impregnation of fibre saturated wood with monomeric silane solutions, and impregnation with pre-hydrolysed partly oligomeric silanes. Wood properties such as cell wall bulking, anti-swelling efficiency (ASE), moisture uptake and durability were more significantly improved in samples treated with monomeric silanes than in samples treated with oligomeric silanes. SEM-EDX mapping showed that this treatment resulted in a higher degree of silicon incorporation into the cell wall, although the weight percent gain (WPG) was lower compared to the treatment with pre-hydrolysed partly oligomeric silanes. The resistance against soil micro-organisms was enhanced in the initial phase of incubation especially in those samples treated with organo-functional-alkoxysilanes. In miniaturised block tests with the white-rot basidiomycete Trametes versicolor, an improved durability was observed within the test period. During an air conditioning step, a weight loss of the treated samples occurred which was accompanied by a reduction in bulking and ASE. The initial reduction of moisture uptake observed after treatment diminished almost completely. This effect was explained by an ageing of the gels in the wood cell wall which is a consequence of uncompleted hydrolysis and condensation of the silanes during the treatment.     

The effect of lupins as compared with peas and oats on the yield of the subsequent winter barley crop

New high yielding early maturing cultivars of lupins have been introduced in north-west Europe as grain protein crops in crop rotations. This paper reports on a comparative study of lupins with peas and oats, and of their effect on yield of subsequent winter barley crops. These crops were given five levels of N under irrigated and non-irrigated conditions on sand and loam. Under rain fed conditions the grain yield of pea, oat and lupin varied between 24–36, 34–53 and 18–37 hkg DM ha⁻¹, respectively. Supplemental irrigation raised grain yield of oat to 50–60 hkg DM ha⁻¹, while grain yield in pea was not affected and grain yield in lupin in most cases decreased due to gray mould attack and excessive vegetative growth in the indeterminate lupin variety. Under rain fed conditions, the grain nitrogen content of pea, oat and lupin varied between 137–172, 61–80 and 189–226 kg N ha⁻¹, respectively, and was significantly higher in lupin as compared with pea. On sandy soil, similar low-root densities were found for pea, oat and lupin below 30 cm depth. On sand, at final harvest the residual soil-N of lupin and pea, as measured in a subsequent winter barley crop not supplied with N fertilizer, was 15 and 8–10 kg N ha⁻¹ higher than in winter barley following oat, respectively. The nature of the probably more N-root residues of lupin is discussed. On loam, the residual N of lupin and pea was similar, 18–27 kg N ha⁻¹. On sand, under rain fed conditions preceding lupin and pea as compared with oat, increased the barley grain yield at zero N-application 77 and 49%, respectively; the effect of lupin was significantly higher than that of pea until the highest N-level 120 kg N-application ha⁻¹. On loam under rain fed conditions preceding lupin and pea increased the barley grain yield at zero N-application by 36 and 62%, respectively, as compared with oat; at N-application>60 kg N ha⁻¹ the grain yield was similar after all three crops. For both soil types the same level of effect was found under irrigated conditions. Conclusions: Supplemental irrigation might result in lower grain yield in lupin due to gray mould attack and excessive growth if indeterminate lupin varieties are used. Grain nitrogen yield of lupin is significantly higher than that of pea. On sand, the effect of lupin on the subsequent winter barley grain yield is significantly higher than that of pea, probably due to greater N-root nitrogen residues. On loam, lupin and pea have similar effects on the subsequent winter barley crop.     

Pedo‐ecological consequences of lithological discontinuities in soils—examples from Central Europe

Soil profiles having lithological discontinuities, i.e., stratified or layered profiles, occur worldwide. Their genesis as part of the upper‐regolith formation is comparatively well understood, particularly in Central Europe where extensive research on relic periglacial cover beds has been done. But the pedogenetic and ecological implications of lithologically discontinuous soils (LDS) are less well known. Most textbooks rely on the so‐called A‐B‐C‐model as a climate‐driven approach to soil formation. After reviewing definitions and concepts of lithological discontinuities and how they form, we present a pedogenetic model extending the traditional approach by considering substrate genesis and regolith dynamics. The consequences in the interpretation of vertical distributions of parameters of soil acidification and of heavy metals are investigated for typical soil profiles from the W Ore Mountains and the central‐German lowlands. Results show how lithological discontinuities influence the depth gradients and that properties inherited from substrate should be distinguished, if possible, from those developed by pedogenesis.     

Colluvisols under cultivation in Schleswig-Holstein. 1. Genesis,definition and geo-ecological significance

In Schleswig-Holstein, F.R.G., two typical soil associations from loamy boulder marl and loamy pleistocene sands were mapped and ecologically characterized in order to show the necessity of an adequate classification of Colluvic Cumulic Anthrosols (Colluvisols). More than 50% of the original soils have been altered by erosion. The depth of the colluvic wM horizon ranges between 10 cm and more than 100 cm. The amounts of soil organic matter and plant available nutrients are much higher in the Colluvisols than in the haplic soils. Soil classification does not deal with all these aspects with regard to mapping of colluvic soils. In the German soil classification adequate and ecologically significant definitions and instructions of the nomenclature of colluvic soils are not available. Therefore, a proposal is presented to classify colluvic soils. In addition the threshold value of 0.6% soil organic matter in sandy parent material is too low in order to distinguish a Bv from a M horizon; 1.0% would be a more acceptable value. It would be necessary to investigate yield on erodic, non-erodic and colluvic soils in order to determine the effect of erosion and accumulation on crop yield.     

Species composition of arbuscular mycorrhizal fungi in two mountain meadows with differing management types and levels of plant biodiversity

Species composition of arbuscular mycorrhizal fungi (AMF) was analysed in two differently managed mountain grasslands in Thuringia (Germany). Arbuscular mycorrhizal fungi were studied in the roots of 18 dominant plant species from a total of 56 (32%). Additionally, spores of AMF were isolated from soil samples. Arbuscular mycorrhizal fungi species composition was analysed based on 96 sequences of the internal transcribed spacer of the nuclear ribosomal DNA, 72 originated from mycorrhizal roots, and 24 originated from AMF spores. Phylogenetic analyses revealed a total of 19 AMF species representing all genera of the Glomeromycota except Scutellospora and Pacispora. Despite a different farming intensity, resulting in remarkable differences concerning their plant species diversity (27 against 43 plant species), the diversity of AMF was found to be similar with 11 species on the intensively farmed meadow and ten species on the extensively farmed one. Nevertheless, species composition between both sites was clearly different. It thus seems likely that the AMF species composition, but not necessarily the species number, is related to above ground plant biodiversity in the system under study.     

Diverse plant and animal genetic records from Holocene and Pleistocene sediments

Genetic analyses of permafrost and temperate sediments reveal that plant and animal DNA may be preserved for long periods, even in the absence of obvious macrofossils. In Siberia, five permafrost cores ranging from 400,000 to 10,000 years old contained at least 19 different plant taxa, including the oldest authenticated ancient DNA sequences known, and megafaunal sequences including mammoth, bison, and horse. The genetic data record a number of dramatic changes in the taxonomic diversity and composition of Beringian vegetation and fauna. Temperate cave sediments in New Zealand also yielded DNA sequences of extinct biota, including two species of ratite moa, and 29 plant taxa characteristic of the prehuman environment. Therefore, many sedimentary deposits may contain unique, and widespread, genetic records of paleoenvironments.     

Ash and biochar amendment of coarse sandy soil for growing crops under drought conditions

Appropriate soil amendments may increase plant available water and crop yields on coarse sandy soils under drought conditions. In this study, we applied straw ash or straw biochar from gasification to a Danish coarse sandy subsoil to assess the effects on soil water retention, evapotranspiration and crop yields. Spring barley (2016, 2017) and winter wheat (2018) were grown over three years in columns containing 25cm of organic matter-rich topsoil, 80 cm of amended coarse sandy soil (1.5%, 3%, 6% wt. ash or 1% wt. biochar or control soil) and 45 cm of un-amended subsoil. Precipitation, evaporative demands and soil moisture were recorded across the growth seasons, with 2018 having severe drought conditions. This year evapotranspiration levels increased with increasing ash and biochar content (by 54% and 33% for the 6% ash- and 1% biochar-amended soils, respectively), and plant dry matter increased by 18% in both the 1% biochar- and 6% ash-treated soils compared to the untreated control. A linear relationship was established between in situ field capacity and ash dosage (R² = .96), showing an increase of 2.2% per percentage (wt.) of ash added, while the 1% biochar treatment increased the capacity by 3.5%, indicating a higher efficiency than for ash. However, we did not find significant positive effects on grain yields. The results show that ash and biochar have the potential to significantly increase soil water retention, evapotranspiration and total dry matter yield in drought conditions, but that this may not correspond to an increase in grain yield.