1. Elevated ozone prevents acquisition of available nitrogen due to smaller root surface area in poplarTanja Mrak, Klemen Eler, Ovidiu Badea, Yasutomo Hoshika, Elisa Carrari, Elena Paoletti, Hojka Kraigher, 2020, original scientific article Abstract: Aims Poplars are ecologically and economically important tree genus, sensitive to ozone (O3). This study aimed to investigate modifying effects of elevated O3 on poplar root response to nutrient addition. Methods In pot experiment, young trees of an O3-sensitive Oxford poplar clone (Populus maximoviczii Henry x berolinensis Dippel) growing in soil with three levels of P (0, 40 and 80 kg ha-1) and two levels of N (0 and 80 kg ha-1) were exposed to three levels of O3 (ambient - AA, 1.5 x AA, 2.0 x AA) at a free air exposure facility. After one growing season, root biomass, fine root (<2 mm) nutrient concentrations and ratios, and fine root morphology were assessed. Results Nitrogen addition resulted in an up to +100.5% increase in coarse and fine root biomass under AA, and only up to +46.3% increase under 2.0 x AA. Elevated O3 and P addition had a positive effect, while N had a negative effect on P concentrations in fine roots. Nitrogen limitation for root growth expressed as a N:P ratio was more pronounced at elevated O3. Nitrogen addition increased root surface area per soil volume by +78.3% at AA and only by +9.9% at 2.0 x AA. Conclusions Smaller root surface area per soil volume at elevated O3 prevented acquisition of available N, rendering N fertilization of young poplar plantations in such conditions economically and environmentally questionable. Keywords: fine roots, nitrogen, phosphorus, Populusmaximoviczii x berolinensis, ozone, Poplar Published in DiRROS: 16.06.2020; Views: 2247; Downloads: 1295 Full text (775,68 KB) This document has many files! More... |
2. Different belowground responses to elevated ozone and soil water deficit in three European oak species (Quercus ilex, Q. pubescens and Q. robur)Tanja Mrak, Ines Štraus, Tine Grebenc, Jožica Gričar, Yasutomo Hoshika, Giulia Carriero, Elena Paoletti, Hojka Kraigher, 2019, original scientific article Abstract: Effects on roots due to ozone and/or soil water deficit often occur through diminished belowground allocation of carbon. Responses of root biomass, morphology, anatomy and ectomycorrhizal communities were investigated in seedlings of three oak species: Quercus ilex L., Q. pubescens Willd. and Q. robur L., exposed to combined effects of elevated ozone (ambient air and 1.4 x ambient air) and water deficit (100% and 10% irrigation relative to field capacity) for one growing season at a free-air ozone exposure facility. Effects on root biomass were observed as general reduction in coarse root biomass by -26.8 % and in fine root biomass by -13.1 % due to water deficit. Effect on coarse root biomass was the most prominent in Q. robur (-36.3 %). Root morphological changes manifested as changes in proportions of fine root (<2 mm) diameter classes due to ozone and water deficit in Q. pubescens and due to water deficit in Q. robur. In addition, reduced fine root diameter (-8.49 %) in Q. robur was observed under water deficit. Changes in root anatomy were observed as increased vessel density (+18.5 %) due to ozone in all three species, as reduced vessel tangential diameter (-46.7 %) in Q. ilex due to interaction of ozone and water, and as generally increased bark to secondary xylem ratio (+47.0 %) due to interaction of ozone and water. Water deficit influenced occurrence of distinct growth ring boundaries in roots of Q. ilex and Q. robur. It shifted the ectomycorrhizal community towards dominance of stress-resistant species, with reduced relative abundance of Tomentella sp. 2 and increased relative abundances of Sphaerosporella brunnea and Thelephora sp. Our results provide evidence that expression of stress effects varies between root traits; therefore the combined analysis of root traits is necessary to obtain a complete picture of belowground responses. Keywords: ozone, drought, fine roots, ectomycorrhiza, anatomy, morphology, plants Published in DiRROS: 20.02.2020; Views: 2488; Downloads: 1676 Full text (1,03 MB) This document has many files! More... |
3. Ectomycorrhizae of Norway spruce from its southernmost natural distribution range in SerbiaMarina Katanić, Saša Orlović, Tine Grebenc, Marko Bajc, Saša Pekeč, Milan Drekić, Hojka Kraigher, original scientific article Abstract: Norway spruce (Picea abies Karst.) reaches its southernmost limit in the mountainous regions of south Serbia and Bulgaria. The species is a regionally important timber species for the wood industry and a significant host for various ectomycorrhizal fungi, including edible species. We analysed ectomycorrhizal community and fine root parameters of high continental / subalpine Norway spruce stands at three sites (Stara planina, Kopaonik, Tara) located in protected areas in Serbia. In addition, we assessed the potential effects of altitude and growing season on the ectomycorrhizal diversity and fine root parameters. Using standardised sampling in combination with morpho-anatomical and molecular identification of ectomycorrhizae, we recorded 29 different anatomorphotypes. None of the identified fungi belonged to commercial edible fungal species. Compared to other Norway spruce ectomycorrhiza studies in central Europe, sites in Serbia exhibited lower species diversity and different dominant species composition, with Cenococcum spp. and Russula spp. as the dominant ectomycorrhizal fungi. A number of ectomycorrhizal types and the value of the species richness index differed between Stara planina and Tara in the autumn, but the influence of site and season on the studied diversity indices was not significant. The total number of fine roots increased in the spring, while percentage of vital ectomycorrhizal root tips increased in the autumn. This study was the first examination of Norway spruce ectomycorrhizal communities at the edge of the natural geographical range of the species. Keywords: ectomycorrhiza, Picea abies Karst, community structure, fine roots Published in DiRROS: 22.01.2019; Views: 3022; Downloads: 1824 Full text (553,32 KB) This document has many files! More... |