Environmental Impact on Soil Nematodes Following the Use of the Ivermectin Sustained-release Bolus or the Nematophagous Fungus Duddingtonia flagrans to Control Nematode Parasites of Cattle in Sweden

Management of nematode parasites of grazing livestock is essential, but there is concern about the potential environmental risk from agents used in their control. In this experiment, parasites in young cattle were controlled, using ivermectin boluses or the predacious fungus Duddingtonia flagrans , over 3 years. Treatment differences were sought among the soil nematodes recovered from soil samples collected from the paddocks on which treated animals grazed, and compared with similar samples taken from an untreated control paddock. Analysis of the soil nematode fauna on 21 occasions failed to demonstrate any impact of parasite management on soil nematodes. In 0-22 mm soil total nematode abundance averaged 524 000 m -2 , with 18 nominal taxa and H' diversity 2.41. There were both underlying paddock and year-to-year, climate-related, differences. The results of this trial not only confirm the lack of any adverse environmental impact of D. flagrans , a promising biological control agent, on soil nematodes, but also fail to show any impact arising from the use of ivermectin boluses.     

Direct measurement of rice bran lipase activity for inactivation kinetics and storage stability prediction

Rice bran is a rich source of valuable nutrients and has potential for high-value applications. Endogenous lipases catalyze the hydrolysis of rice bran oil to free fatty acids, which initiates lipid oxidation. The evaluation of the success of rice bran stabilization processes in terms of the degree of lipid oxidation and shelf-life has so far relied on the measurement of free fatty acid content over a storage period of 3–6 months. In the present study, a photometric and a titrimetric pH-stat method for direct lipase activity measurement immediately after debranning were adapted to rice bran. The photometric method was further applied to determine rice bran lipase/esterase inactivation kinetics, which are useful to optimize stabilization treatments in order to prevent overprocessing and retain maximum level of nutrients. Rice bran was heat-treated in a specialized, hermetically sealable reactor at controlled holding times (5–40 min), temperatures (70–145 °C) and moisture contents (10–20%). Temperature dependency of the lipase/esterase inactivation rate could be described by the Arrhenius equation. Empirical findings on the importance of moisture content for effective rice bran stabilization could be quantified. Furthermore, the results demonstrate the great potential of the method to predict the shelf-life of stabilized rice bran without time-consuming storage tests.     

Efficient discrimination of oat and pea roots by cluster analysis of Fourier transform infrared (FTIR) spectra

Understanding belowground competition of plants requires a simple method for species identification of plant roots. This study investigates Fourier transform infrared (FTIR)-attenuated total reflexion (ATR) spectroscopy followed by cluster analysis for the discrimination of pea and oat roots. Pea and oat plants were grown under various conditions – in moist paper, soil-compost mixture, soil, in the greenhouse and field – to enhance the intra-species variability of their chemical composition. FTIR-ATR spectra of young-to-old roots from four independent experiments were recorded and represent, like a fingerprint, the chemical sample composition such as lipids, proteins, carbohydrates, etc. To group the spectra according to their spectral similarity in a dendrogram, cluster analysis was performed. The experimental approach discriminated pea and oat roots 100% successfully. The perfect discrimination of pea and oat roots, even from intercropped plants, strikingly demonstrates the potential of the method.     

High organic carbon stock in a karstic soil of the Middle-European Forest Province persists after centuries-long agroforestry management

Little is known on soil organic carbon (SOC) stocks in karst areas worldwide, although many of them have seen long-term application of agroforestry systems with a potential for carbon sequestration. Therefore, our study aimed to assess landscape-level SOC concentration and stock in the Silica Plateau, a part of the Slovak Karst Biosphere Reserve located in the Western Carpathians (Slovakia) with a centuries-long agroforestry record. The most represented local soil units are Chromi-Rendzic Leptosols and Chromic Cambisols with clayey loam texture, C/N ratio 9–12, and $ {\text{pH}}_{{{\text{H}}_{2} {\text{O}}}} $ 6.6–6.2 in their organo-mineral surface horizons. Mull surface humus form prevails under mixed forest stands dominated by hornbeam (Carpinus betulus L.), oak (Quercus petraea L.), and beech (Fagus sylvatica L.). A total of 2,700 soil samples were collected from 150 soil pits. Both SOC concentrations and stocks were determined for the 0–60?cm mineral soil layer. Soil stoniness was accounted for by means of electrical resistivity tomography. According to the analysis of covariance, cropland SOC concentration (0.026?g?g^?1) is significantly lower compared to forestland (0.040?g?g^?1) and pastureland (0.041?g?g^?1) (P?<?0.01). During the period of 130?years after forest clearing, cropland SOC stock has been reduced at an exponential decay rate of ca 0.002?year^?1, while the SOC stock in pastureland has increased following land use change from cropland by approximately 30% during the same period of time. Irrespective of land use history, overall SOC stock is high reaching on average 207.4?Mg?ha^?1, out of which 66% are stored within 0–30?cm and 34% within 30–60?cm soil layers.     

Changes in soil nematode populations indicate an annual life cycle at Cape Hallett, Antarctica

Soil biological studies have suggested that generations of terrestrial nematodes in continental Antarctica may take many years. We sampled soil nematodes at three sites in the Adélie penguin colony at Cape Hallett on four dates in a two month sampling period (16 November 2002–18 January 2003). The size class distribution of over 3500 nematodes, and the occurrence of adults, indicate an annual life cycle of the bacterial-feeding Panagrolaimus davidi and Plectus murrayi, at each site. Nematode abundance ranged from 2 to 1375/g dry soil. Moderate temperatures and the regular presence of free water underlie this biological activity and related contribution to soil processes.     

Long-term changes in topsoil nematode populations in grazed pasture under elevated atmospheric carbon dioxide

Increasing atmospheric CO₂ concentrations are expected to affect ecosystems processes, and while a New Zealand study reported a response in soil biological activity after 4 years of CO₂ enrichment, apparently reflecting increased populations of Longidorus elongatus, similar findings have not been reported from other sites. Soil microfauna in 0–10 cm soil under a sheep-grazed pasture on a sand was assessed quarterly in FACE rings that were either at ambient CO₂ or had been exposed to 475 μl l⁻¹ CO₂ for some 9 years. Although the area had been subject to a severe drought and microfaunal populations were lower than previously found, the effects of elevated CO₂ on microfaunal populations were broadly similar to those at 4 years. Average populations of the root-feeding L. elongatus increased from 67,000 to 233,000 m⁻² (3.48×) compared with a 4.26× increase after 4 years; microbial-feeding nematodes increased slightly, while predacious nematodes showed a 2.0× increase. A pot experiment showed an additive effect of elevated CO₂ and L. elongatus abundance in reducing specific root length. That similar effects have been found 4 and 9 years after CO₂ enrichment commenced suggests they are real, and emphasises the difference to other sites around the world where much lower responses to elevated CO₂ have been found. This, in part, reflects the unique combination of soil, plant and soil biological conditions at each site and confirms the strong effect of soil type and vegetation on soil biological processes. Just as the effects of global climate change on a given region are idiosyncratic, so it seems are the effects of elevated CO₂ on soil and ecosystem processes. In part, this reflects our limited understanding of below-ground processes.     

Blossom‐end rot and fruit cracking of tomato grown in net‐covered greenhouses in Central Thailand can partly be corrected by calcium and boron sprays

Two tomato (Lycopersicon esculentum Mill.) cultivars King Kong 2 (KK2) and FMTT 260 (FMTT) were grown in a net‐covered greenhouse in Central Thailand to investigate the influence of fruit applications of combined aqueous calcium (Ca) and boron (B) solutions amended or not with the tenside Glucopon® on fruit yield and quality. Special attention was paid on blossom‐end rot (BER) and fruit cracking (FC), two prevailing disorders in tomato and main causes for non‐marketability of tomato fruits under the conditions of protected cultivation in Central Thailand. While no effect of the additional Ca and B applications on total fruit yield was observed, the composition of the non‐marketable fraction of fruit yield differed significantly between treatments and cultivars. Cultivar KK2 proved to be highly susceptible to both BER and FC and, therefore, produced less marketable fruits than cv. FMTT. The Ca and B sprays decreased the incidence of BER but increased FC at the same time. Addition of the tenside Glucopon® to the Ca and B solutions did not yield any further advantage. The contrasting effect of the Ca and B sprays on BER and FC resulted in similar levels of non‐marketable fruit yield in the treatments with or without the sprays for both cultivars. The nutrient status in different fruit segments was surveyed during fruit development. The Ca concentration in the distal end of the fruit during the time of rapid fruit growth was correlated with the BER incidence in mature fruits. Since additional Ca and B sprays are labor‐intensive and did not significantly reduce the portion of non‐marketable fruits, the selection of cultivars insusceptible to BER and FC appears to be of highest priority when conditions favoring these disorders are to be expected. This is particularly true for protected cultivation in Central Thailand.     

Phylogenetic relationship and genetic differentiation of Populus caspica and Populus alba using cpDNA and ITS noncoding sequences

Populus caspica Bornm.(section Leuce and subsection Albida), one of the most endangered endemic tree species in the Hyrcanian Forest in Iran, has numerous morphological characteristics that are closely similar to Populus alba; to clarify their taxonomic relatedness and genetic differentiation and thus inform conservation strategies, we used the noncoding regions of chloroplast DNA(cpDNA; trnL-F and trnH-psbA) and the internal transcribed spacer(ITS). Leaf samples were collected from six populations across northern Iran. cpDNA and ITS fragments were amplified by universal primers using the PCR technique and directed sequencing. The results showed that P. caspica is genetically differentiated from P.alba, and two ITS variants were detected within some P.caspica individuals. Conflicts between topologies from ITS and plastid genomes were observed. High differentiation of P. caspica from the other Populus species shown in this study confirmed the diverging taxonomic status of this endangered species. We recommend in situ conservation measures(e.g., protected areas) for at least several populations of this species, especially in the plain regions of the Hyrcanian forest.