Time filter

Source Type

Geisenheim, Germany

Thomas L.K.,University of Marburg | Leyer I.,University of Marburg | Leyer I.,University of Geisenheim
Plant Ecology

In northern Patagonia, riparian ecosystems are highly modified due to alien plant invasions. The establishment of non-native willows and poplars has unknown effects for Salix humboldtiana, the only native floodplain tree species in this region. To clarify establishment processes and to assess whether interspecific competition among the Salicaceae taxa may occur and therefore whether the native species can coexist in the long term, we analysed age structure and growth performances of the dominant four taxa within mixed adult forest stands along the Río Negro, Argentina. Low mean ages of <15 years for all four taxa within 20 stands could be detected and suggest frequent and severe disturbances resulting in the removal of existing vegetation and subsequent creation of sites for establishment. Trees of the same stand showed the same age structure indicating joint establishment events with all taxa involved. A significant better growth performance (basal area, crown diameter) could be proved for the invasive willows. Considering the upper and middle river separately in a total of 88 studied plots, S. humboldtiana was more frequent at the middle river stretch, while invasive willows showed an opposing pattern suggesting a downstream directed invasion process. The results showed that competition pressure in mature mixed stands could affect S. humboldtiana. However, these stands are usually removed by river dynamics creating new sediment bars and islands. These processes enable S. humboldtiana seeds to germinate frequently which may compensate for its inferior growth performance and potential impacts by the invasive willows and poplars. © 2014 Springer Science+Business Media Dordrecht. Source

Bozzi J.A.,Instituto Nacional de Tecnologia Agropecuaria | Liepelt S.,University of Marburg | Ohneiser S.,University of Marburg | Gallo L.A.,Instituto Nacional de Tecnologia Agropecuaria | And 6 more authors.
Applications in Plant Sciences

Premise of the study: We present a set of 23 polymorphic nuclear microsatellite loci, 18 of which are identified for the first time within the riparian species Salix humboldtiana (Salicaceae) using next-generation sequencing. Methods and Results: To characterize the 23 loci, up to 60 individuals were sampled and genotyped at each locus. The number of alleles ranged from two to eight, with an average of 4.43 alleles per locus. The effective number of alleles ranged from 1.15 to 3.09 per locus, and allelic richness ranged from 2.00 to 7.73 alleles per locus. Conclusions: The new marker set will be used for future studies of genetic diversity and differentiation as well as for unraveling spatial genetic structures in S. humboldtiana populations in northern Patagonia, Argentina. © 2015 Bozzi et al. Published by the Botanical Society of America. Source

Vollmer E.,University of Geisenheim | Keicher R.,University of Geisenheim | Schwarz H.-P.,University of Geisenheim

With plant protection in hedgerow system vineyards (minimum pruning) the resultant foliage density hinders spray penetration to target surfaces with insufficient wetting of all parts of the plants. The investigation presented here tests the efficacy of different sprayer designs in these types of vineyards. Trial procedure is based on already existing methods of leaf deposit measurement in espalier vineyards and modified to account for the increase in leaf area and the specific leaf canopy geometry. Trial results show a very broad scatter of leaf deposit and a marked deficit of deposits on the foliage canopy roof area. The recorded data contribute to further development of application methods. Special attention is required in future investigations toward increasing the number of spot samplings. Source

Discover hidden collaborations