Effects of cuvette surface material on ammonia‐, nitrous oxide‐, carbon dioxide‐, and methane‐concentration measurements     

Martina Predotova  Roland Kretschmann  Jens Gebauer  Andreas Buerkert 《植物养料与土壤学杂志》2011,174(3):347-349

Closed‐chamber systems are commonly used to determine gaseous C and N emissions from agricultural soils. We investigated the effects of eight cuvette surfaces on two standard gas concentrations of NH₃, N₂O, CO₂, and CH₄ under laboratory conditions. Cuvette surface materials differentially affected gas adhesion or recovery as a function of the type and the concentration of the gases. Given the strong effects on results of gas measurements in closed‐chamber systems, both the type and the concentration of the measured gases need to be considered in selecting cuvette surface materials.  相似文献   

Detection of duplicates among repatriated Nordic spring barley (Hordeum vulgare L. s.l.) accessions using agronomic and morphological descriptors and microsatellite markers     

Birgitte Lund  Rodomiro Ortiz  Roland von Bothmer  Sven-Bode Andersen 《Genetic Resources and Crop Evolution》2013,60(1):1-11

  相似文献   

Genetic diversity in farmer grown spring barley material from Kyrgyzstan     

Birzhan Usubaliev  Agnese Kolondinska Brantestam  Björn Salomon  Larisa Garkava-Gustavson  Roland von Bothmer 《Genetic Resources and Crop Evolution》2013,60(6):1843-1858

Barley (Hordeum vulgare L.) is one of the economically important cereal crops grown in the highlands of the Kyrgyz Republic. In marginal agricultural areas of the country barley is considered as irreplaceable and very suitable fodder crop for livestock. In this study the genetic diversity of currently grown farmers’ spring barley material from Naryn and Issik-Kul provinces is described. In order to capture maximum diversity present in farmer field’s different morphological types were collected. The 22 spring barley accessions collected in 2008 were described morphologically and analysed using fourteen simple sequences repeat (SSR) markers. Most material was two-rowed barley, 78 %, whereas six-rowed barley was only 22 %. The spike colours present were light yellow, dark yellow, brown and violet. The material varied also for such characters as length of spike and number of kernels per spike. For the SSR loci 129 alleles were detected with an average of 9.3 alleles per locus and a genetic diversity with an average of h = 0.721 per locus. Based on analysis of molecular variance the 71.3 % of genetic diversity accounted for within accession variation, whereas 27.4 % for among accession variation. The variation between provinces was not significantly different. A group of two-rowed barley was identified that was more closely related to six-rowed barley than to the rest of the two-rowed barley material. Two-rowed material currently grown in Kyrgyzstan is more diverse than six-rowed barley (h = 0.65, A = 8.8 vs. h = 0.59, A = 3.1). From this study we could conclude that the materials nowadays grown by farmers are mixtures. Since there are no geographic differentiation between these mixtures suggests that materials is frequently inter-exchanged between farmers and are most probably not landrace material. The question concerning the origin of these mixtures remains unsolved and further investigation will be carried out to identify sources of variation in farmers’ field.  相似文献   

Infection conditions for Neofabraea perennans and Phacidiopycnis washingtonensis on developing apple fruit in the orchard     

Holthusen  Hinrich H. F.  Weber  Roland W. S. 《European journal of plant pathology / European Foundation for Plant Pathology》2021,161(4):895-906

European Journal of Plant Pathology - In Northern Germany, a major share of postharvest losses of apple fruit is due to preharvest infections by pathogenic fungi. Little is known about their...  相似文献   

Features and applications of a field imaging chlorophyll fluorometer to measure stress in agricultural plants     

Linn  Alexander I.  Zeller  Alexander K.  Pfündel  Erhard E.  Gerhards  Roland 《Precision Agriculture》2021,22(3):947-963

Most non-destructive methods for plant stress detection do not measure the primary stress response but reactions of processes downstream of primary events. For instance, the chlorophyll fluorescence ratio F_v/F_m, which indicates the maximum quantum yield of photosystem II, can be employed to monitor stress originating elsewhere in the plant cell. This article describes the properties of a sensor to quantify herbicide and pathogen stress in agricultural plants for field applications by the F_v/F_m parameter. This dedicated sensor is highly mobile and measures images of pulse amplitude modulated (PAM) chlorophyll fluorescence. Special physical properties of the sensor are reported, and the range of its field applications is defined. In addition, detection of herbicide resistant weeds by employing an F_v/F_m-based classifier is described. The PAM-imaging sensor introduced here can provide in-field estimation of herbicide sensitivity in crops and weeds after herbicide treatment before any damage becomes visible. Limitations of the system and the use of a classifier to differentiate between stressed and non-stressed plants based on sensor data are presented. It is concluded that stress detection by the F_v/F_m parameter is suitable as an expert tool for decision making in crop management.

  相似文献   

Iron isotope fractionation in soil and graminaceous crops after 100 years of liming in the long-term agricultural experimental site at Berlin-Dahlem,Germany     

Bei Wu  Yi Wang  Anne E. Berns  Kathlin Schweitzer  Sara L. Bauke  Roland Bol  Wulf Amelung 《European Journal of Soil Science》2021,72(1):289-299

  相似文献   

Value of permanent grassland habitats as reservoirs of Festuca pratensis Huds. and Lolium multiflorum Lam. populations for breeding and conservation     

Madlaina K. I. Peter-Schmid  Roland Kölliker  Beat Boller 《Euphytica》2008,164(1):239-253

European natural and semi-natural grassland form reservoirs of genetic resources containing highly adapted and variable ecotype populations of forage plants. Variation within these reservoirs is stimulated by variation in natural and anthropogenic site-related factors. Changes in agricultural practices lead to the loss of many characteristic habitats. In order to preserve resources for breeding, targeted conservation strategies for germplasm in gene banks (ex-situ) or on site (in-situ) are needed. In order to define site-related criteria for the potential of habitats to preserve valuable resources for breeding and conservation, 38 different habitats across Switzerland were selected to collect Festuca pratensis Huds. and Lolium multiflorum Lam. ecotype populations. Phenotypic variation and population differentiation of 60 single plants were evaluated in a field experiment using 16 morpho-physiological traits. For F. pratensis, ecotype populations and cultivars were clearly separated and there was a significant correlation between diversity of morphological traits and geographic location of sampling sites. For L. multiflorum no clear separation of ecotype populations and cultivars was observed suggesting gene flow from adjacent temporary leys into permanent grassland. Several ecotype populations were superior to cultivars in important traits such as early heading or resistance to winter damage, indicating the importance of natural habitats as a reservoir of genetic resources for breeding. In conclusion, maintenance of permanent grassland in contrasting environments appears to be a promising strategy for preserving valuable genetic variation of forage grasses. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

Two-Year Weed Seedling Population Responses to a Post-Emergent Method of Site-Specific Weed Management     

Williams  Martin M.  Gerhards  Roland  Mortensen  David A. 《Precision Agriculture》2000,2(3):247-263

Field experiments were conducted to determine how a site-specific weed management practice in Zea mays L. influenced the numerical and spatial distribution of a naturally occurring weed infestation in Z. mays and the succeeding Beta vulgaris L. crop. Compared to conventional broadcast herbicide applications, site-specific herbicide applications reduced herbicide load by 11.5 and 98.0% in two separate Z. mays fields. The broad range in outcomes was attributed to the spatial aggregation and density of target weed populations. While herbicide use was successfully reduced at field locations with low weed density, most survivors of multiple control tactics were in locations with the highest initial density. A greater understanding of interactions between weed management and weed density would increase the likelihood that site-specific weed management offers long-term improvements over conventional approaches.  相似文献   

Levels and distribution of allozyme and RAPD variation in populations of Elymus fibrosus (Schrenk) Tzvel. (Poaceae)   总被引：5，自引：0，他引：5  

Oscar Díaz  Gen-Lou Sun  Björn Salomon  Roland von Bothmer 《Genetic Resources and Crop Evolution》2000,47(1):11-24

To study the magnitude and nature of genetic variation in E. fibrosus, the levels and distribution of allozyme and RAPD variations were investigated in populations collected from Finland and Russia. The results obtained from the allozyme and RAPD studies were compared to each other in 10 of the populations. The allozyme analysis showed that 6 of 12 presumed loci (50%) were polymorphic within the species, while the mean number of polymorphic loci within populations was 4.8%. The mean number of allele per locus for the species was 1.5 and 1.05 across the populations. Genetic diversity at the species level was low (H _es = 0.025), and the mean population genetic diversity was even lower (H _ep = 0.007). Both these values were much lower than the average for other Elymus and self-fertilising species. The largest proportion of the total allozyme diversity was found among, rather than within the populations (G _ST = 0.70). The allozyme genetic distances between the populations did not reflect geographic distances. Cluster and principal coordinates analyses revealed the same allozyme relationship patterns among the populations. A comparison of allozyme and RAPD variation in 10 of the populations showed differences in the amount of genetic variation. The RAPD analysis revealed higher levels of variation (A _p = 1.19, P _p = 20.3 and H _ep = 0.09) than the allozyme one) A _p = 1.06, P _p = 5.8 and H _ep = 0.008). For both markers, the largest proportion of the total gene diversity was found among the populations studied (G _st = 0.63 for RAPDs and G _st = 0.65 for allozyme). In contrast to the allozyme analysis, the RAPD based genetic distances did reflect geographic distances. The cluster and principal coordinates analyses showed different grouping of populations for each data set. There was a positive, but not significant, correlation (r = 0.41) between the genetic distance matrices resulting from these markers. Regional comparison revealed that the Finnish populations had a higher diversity than the Russian ones. Generally, this study indicates that E. fibrosus contains low genetic variation in its populations. The results are discussed in the context of conservation of the species.  相似文献   

Living in a Dusty World: Airborne Dust as a Key Factor for Alpine Lakes     

Psenner  Roland 《Water, air, and soil pollution》1999,112(3-4):217-227

For a long time studies on precipitation and lake-water chemistry have focussed on the deposition of strong acids. Dust in snow and rain was analyzed much less intensively, but recent findings suggest that it may be the missing link which explains why many low-alkalinity lakes in the Alps and the Pyrenees did not become acidic and nutrient levels are seasonally high, whereas lakes in areas which are rarely influenced by dust depositions, for instance in Scandinavia, have acidified. Beside being a dominant factor for nutrient inputs to oceans, rain forests and remote lakes, dust can also play a major role in global warming and cooling, and it may significantly contribute to soil formation at mountain sites in the Mediterranean. I suggest that future changes in dust deposition and warming will be key factors for the development of alpine lakes.  相似文献