Studies of Soils, Soil Water and Stream Water at a Small Catchment near Guiyang, China

Acid deposition is considered to be a major environmental problem in China, but information about effects on soils and waters is scarce. To contribute to increased knowledge about the problem a small catchment (about 7 ha) in the outskirts of Guiyang, the provincial capital of Guizhou in south-western China, was instrumented for collection of precipitation, throughfall, soil water and stream water. In addition soil samples have been collected and analyzed for key properties. Median pH in the precipitation is 4.40 (quartiles: 4.19 and 4.77) and the median sulfate concentration 228 µeq/L (quartiles: 147 and 334 µeq/L). The dry deposition of both SO₂ and alkaline dust is considerable. The sum of wet deposition of sulfate and dry deposition of SO₂ has been estimated to about 8.5 gSm^-2yr^-1. The total S-deposition may be somewhat higher due to dry deposition of sulfate and occult deposition. In soil water, SO₄ ^2- is the major anion, generally ranging from 300 to 2500 µeq/L in the different plots. Calcium is an important cation, but there is also a considerable contribution of aluminum from the soil. In some of the plots the concentrations of inorganic monomeric aluminum (Ali) are typically between 200 and 400 µm. Potential harmful levels of aluminum and/or high Ali/(Ca²⁺ + Mg²⁺) molar ratios occur in the catchment, but damages to vegetation have not yet been reported. In most cases exchangeable aluminum accounts for between 75 and 95% of the total effective cation exchange capacity (CEC_E) in the mineral soils. The aluminum chemistry cannot easily be explained by conventional models as the Gaines-Thomas ion-exchange equation or equilibrium with an Al(OH)₃ mineral phase. The stream water is generally less acidic and has considerably lower concentrations of aluminum than the soil water, even though quite acid events have been observed (pH < 4.4). The median pH values are 4.9 and 5.0 in the two first order streams and 6.3 in the dam at the lower boarder of the catchment.     

Pollen characteristics and stigma receptivity for <Emphasis Type="Italic">Anemone coronaria</Emphasis> L.

To obtain crossing products, an efficient pollination and subsequent fertilization is essential. This efficient pollination is achieved by pollen germination and tube growth. Here, these pollen characteristics of 2 genetically differentiating cultivars of Anemone coronaria L. were investigated in vitro. For the essential components boron, calcium and an osmoticant, only calcium showed to be crucial for pollen germination. Boron concentrations influenced the pollen tube length with a concentration of 100 mg l^?1 H₃BO₃ resulting in the longest pollen tubes. For the osmoticant sucrose, a concentration of 100 g l^?1 caused a significant positive effect on both pollen germination and pollen tube length for the 2 cultivars. The cultivars reacted similarly with respect to the investigated compounds. Next to this, the pollen development was correlated with 8 different flower stages in A. coronaria. As a final point, the germination of an optimized pollen germination medium was compared with in vivo pollen germination in cross-pollinations within the same cultivar (identified by aniline blue staining). For ‘Mistral Wine’, pollen germination percentage was lower in vitro than in vivo, while ‘Wicabri Blue’ pollen showed no significant difference in germination rates in vivo and in vitro. To achieve fertilization a following requisite is that the stigma is receptive. To study this, the most receptive female flower stage of the 8 different flower stages for A. coronaria was characterized by aniline blue staining. A. coronaria clearly showed protogyny.     

Report on the 43rd Annual Meeting of the DPG-Working Group Nematology

Journal of Plant Diseases and Protection -     

Identifying plant DNA in the sponging–feeding insect pest <Emphasis Type="Italic">Drosophila suzukii</Emphasis>

Drosophila suzukii (Diptera: Drosophilidae) is a highly polyphagous invasive pest threatening fruit production in the Americas and Europe. The current knowledge of its host plants is mainly based on oviposition and larval development in fruits, while little is known on the diet of the adult flies. This information is important for developing effective control strategies. Here, we examine DNA-based techniques to determine food plants of D. suzukii. Adult flies were fed with raspberries (Rubus idaeus) and allowed to digest up to 72 h after feeding. Raspberry DNA was detected by diagnostic PCR for up to 48 h post-feeding with a significant negative effect of time on DNA detection success but no significant differences between male and female flies in detection probabilities. As D. suzukii walks on plants, its body surface can get contaminated with DNA. With a bleaching experiment, we succeeded to remove contaminating external plant DNA, while the DNA in the gut content stayed unaffected. Finally, field-collected flies were subjected to a next-generation sequencing approach, demonstrating that plant DNA from different host plants can be efficiently detected in both bleached and non-bleached specimens. In order to safeguard against erroneous host plant detections, we recommend bleaching flies before they are subjected to DNA extraction. The current findings encourage the use of DNA-based gut content analysis in D. suzukii to obtain a better understanding of its feeding ecology which is a prerequisite for developing successful control strategies.     

Climatic response and impacts of drought on oaks at urban and forest sites

This study focuses on the climate and growth response of the sessile oak (Quercus petraea (Matt.) Liebl.) and the northern red oak (Quercus rubra L.) using dendrochronological methods. Tree-ring series of street trees in the city of Dresden, Germany and in a nature reserve close to the urban area were analysed, and the climate and growth response and moving correlation functions (CF) were computed. Moreover, the impact of 13 years of drought was examined by superposed epoch analysis (SEA). Our results show that differences emerge from peculiarities of the different site conditions, indicating that city oaks contain a higher level of noise in their ring width data due to human activities that degrade the strength of growth-climate associations. Importantly, climatic conditions during the previous summer and autumn and during the current spring season display significant correlations with annual growth. The stability of the climate–growth relationship was tested via moving correlation functions. A strong increase in the correlation with the temperature and precipitation in April was found for the trees of northern red oak in forests. Drought years induced significant reductions in radial growth for the northern red oak only. Nevertheless, the long-term impact of drought years must be considered as marginal because of the fast recovery of the radial growth after one to two years. In the future, the growth of the northern red oak may be restricted by an increased frequency of droughts and warmer and drier conditions in April.     

Production of chips from potato cultivars (Solanum tuberosum L.) with high sugar content using lactic acid fermentation

Summary Tubers of twelve cultivars ofSolanum tuberosum L., with a varying content of reducing sugars (0.49–2.30 g/100 g fresh weight), were sliced and fermented for up to 48 h by lactic acid bacteria in a brine of 1.5% NaCl, prior to frying. The content of reducing sugars decreased by 80 to 100%, depending on the initial sugar level. Colour of chips was measured using the CIE (1976) L^*a^*b^* colour system, where L^* is lightness, a^* is redness and b^* is yellowness of the material and by IBVL colour cards, photographs used for grading the colour of potato chips. L^*-values were the best measurement of chip colour. The scale of the IBVL colour cards was too narrow (scale 1–9) for this study, as chips from eight of the cultivars were scored lighter than IBVL 9 after 48 h of fermentation. Lighter coloured chips significantly correlated with lower contents of reducing sugars. The sugar content decreased as fermentation time increased. Fermentation time can thus be used to control potato chip colour, and all the cultivars tested can be used for production of chips with regard to colour.     

Brachygnathia in a herd of Angus cattle

Seven cases of brachygnathia in a single calf crop (28 calves) were observed in an Angus herd. Two of the affected calves, 1 female and 1 male, were necropsied and anatomically described. Breeding histories and results of pedigree analysis involving the 7 affected calves indicated the cause of the defect to be genetic with the mode of inheritance that of a single autosomal recessive gene.