Physiological performance of a coastal marsh plant Hydrocotyle vulgaris in natural conditions in relation to mineral nutrition and mycorrhizal symbiosis
Karlsons, A., University of Latvia, Riga (Latvia). Faculty of Biology | Andersone-Ozola, U., University of Latvia, Riga (Latvia). Faculty of Biology | Ievina, B., University of Latvia, Riga (Latvia). Faculty of Biology | Necajeva, J., University of Latvia, Riga (Latvia). Faculty of Biology | Samsone, I., University of Latvia, Riga (Latvia). Faculty of Biology | Ievinsh, G., University of Latvia, Riga (Latvia). Faculty of Biology
The aim of the present study was to assess plant performance by means of non-destructive instrumental methods in a highly heterogeneous natural habitat. More specifically, environmental factors affecting growth and physiological performance of a clonal plant Hydrocotyle vulgaris L. were investigated. Changes in soil salinity, soil mineral characteristics, leaf nutrient concentrations, morphological parameters, chlorophyll fluorescence, and mycorrhizal symbiosis were analysed in different experimental plots of naturally growing H. vulgaris plants. The dynamic nature of interaction between sea water flooding-affected changes in soil salinity and competition-dependent changes in light availability led to micro-environmental heterogeneity differentially affecting physiological performance and growth of H. vulgaris in natural conditions. Plant growth was mostly affected by intensity of photosynthetically active radiation in the respective plots. Increased growth rate in shaded conditions specifically pointed to shade tolerance strategy of H. vulgaris. High heterogeneity of mineral nutrients between the plots was established. However, considerable plasticity of metabolism in respect to highly variable soil concentration of mineral nutrients together with effective mineral adaptation mechanisms ensured optimal supply of material for growth. Photochemistry of photosynthesis was only marginally affected by differences in microenvironmental conditions as shown by respective changes in chlorophyll a fluorescence parameters. Mycorrhizal symbiosis was stimulated by moderately increasing soil salinity and suppressed by relatively high salinity. When the effect of soil salinity was omitted, intensity of mycorrhizal symbiosis was positively associated with intensity of photo-synthetically active radiation.
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