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The influence of distance between host trees and leaf litter removal on population density of Cameraria ohridella have been for the first time examined in an isolated population of horse chestnut (Aesculus hippocastanum L.) trees. The observation was performed in the small town (area 13,58 km²) in Wielkopolska region (West Poland) on the total number of 49 trees: 31 (11 clumps) of them with autumnal leaves removal (controlled sites), and 18 (5 clumps) without this procedure (uncontrolled sites). The main factors determining the extent of the leaf destruction by larvae were the leaf litter removal and the number of subsequent generations on a given tree. The effect of mean distance between trees on the infestation level was statistically significant only for the third generation larvae, when analyzing all sites. There was no significant correlation when checking the impact of mean and short distance on the leaves infestation between controlled and uncontrolled sites. The abundance of the first generation of the larvae of raked sites is possibly a result of low number of in situ overwintering individuals and the number of immigrants from uncontrolled areas. Assuming the random choice of direction of the migration, the effect of the immigrants on the trees which leaves have been disposed of is not as high as it should be expected. Additionally, the moths can be blown away by the wind in a random direction. Consequently, the noted increase in the leaves infestation by the third generation larvae can be result of the rate of population increase innate for the species and only partly a result of immigration from refuge areas.
The aim of the study was to describe the relationships between the flowering phase of selected tree species, whose pollen is known to be allergenic, and fluctuations in the pollen in the air, and to use results obtained for making allergological forecasts. Studies were conducted of five tree taxa: Populus, Ulmus, Salix, Aesculus, and Tilia, in the years 2003-2004. Aeropalinological analyses concerned the above mentioned genera, while in phenological studies specific species were investigated, i.e. the most common representatives of a given genus found in Poland, that is Populus wilsonii, Ulmus laevis Pall. C. K.Schneid., Salix caprea L., Aesculus hippocastanum L. and Tilia cordata Mill. Aerobiological monitoring was performed using a the volumetric method and phenological observations of flowering phases were made according to the Lukasiewicz method. While observing the emergence of individual phenological symptoms and measurements of the concentration of pollen of the investigated taxa in the air of Poznań, a distinct acceleration was observed in 2004, a year that was characterized by a milder winter. This applied not only to the species blooming in early spring, but also to the later ones. Pollen grains of the investigated taxa, except for Aesculus, appeared earlier in aeropalinological observations than the macroscopically observed beginning of flowering in selected trees. Apart from a poplar, the end of flowering in the other trees occurred each year earlier than would follow from the aerobiological observations. This may be explained by the abundance of species within a taxon, and the effect of medium - and long-distance transport.
W minionych 2 latach z siewek kasztanowca z objawami brunatnienia wierzchołków korzeni i ich pękania oraz z porażonej podstawy pędów irgi wyizolowano Phytophthom cambivora. Gatunek ten wykryto również w podłożach spod zamierającej irgi i cyprysików Lawsona. Izolaty tego czynnika chorobotwórczego kolonizowały tkanki korzeni, części pędów oraz blaszki liściowe 3 gatunków roślin. Stwierdzono zróżnicowaną reakcję badanych gatunków roślin na P. cambivora, jak również różnice w szybkości zasiedlania tkanek przez testowane izolaty, w tym zwłaszcza na cyprysiku.
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