50 research outputs found

    Salicylic acid and salicylic acid glucoside in xylem sap of Brassica napus infected with Verticillium longisporum

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    Salicylic acid (SA) and its glucoside (SAG) were detected in xylem sap of Brassica napus by HPLC–MS. Concentrations of SA and SAG in xylem sap from the root and hypocotyl of the plant, and in extracts of shoots above the hypocotyl, increased after infection with the vascular pathogen Verticillium longisporum. Both concentrations were correlated with disease severity assessed as the reduction in shoot length. Furthermore, SAG levels in shoot extracts were correlated with the amount of V. longisporum DNA in the hypocotyls. Although the concentration of SAG (but not SA) in xylem sap of infected plants gradually declined from 14 to 35 days post infection, SAG levels remained significantly higher than in uninfected plants during the whole experiment. Jasmonic acid (JA) and abscisic acid (ABA) levels in xylem sap were not affected by infection with V. longisporum. SA and SAG extend the list of phytohormones potentially transported from root to shoot with the transpiration stream. The physiological relevance of this transport and its contribution to the distribution of SA in plants remain to be elucidated

    A runoff module for use in an atmospheric model

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    Sensitivity studies with a runoff module coupled to a mesoscale atmospheric model

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    On the impact of explicitly predicted runoff on the simulated atmospheric response to small-scale land-use changes--an integrated modeling approach

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    An integrated modeling approach was developed to simulate the water cycle in a closed manner. It consists of (1) procedures for up- and downscaling of the variables and fluxes important for both the hydrological and atmospheric processes, (2) a module to explicitly predict surface and channel runoff, (3) the hydro-thermodynamic soil-vegetation scheme (HTSVS) which was introduced in the (4) nonhydrostatic meso-beta/gamma-scale meteorological model GESIMA (Geesthacht's simulation model of the atmosphere). Comparison of the results provided by simulations with and without consideration of surface and channel runoff shows a remarkable impact of surface runoff on the water cycle within the domain. The results of simulations, wherein, along the rivers, grassland and agriculturally used land were substituted by deciduous forest demonstrate that the atmospheric response to land-use changes is more distinct when surface runoff is considered explicitly than if not. It can be concluded that an integrated modeling techniques of the water cycle, like presented here, can be an important tool for studies on water availability under altered future conditions
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