Browsing by Subject "Soil microorganisms"

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Microbial consortia as inoculants for improvedcrop performance
(2020) Bradácová, Klára; Neumann, Günter
The use of microbial consortia products (MCP) based on combinations of different strains of plant growth-promoting microorganisms (PGPM) and frequently also on non-microbial bio-stimulants (BS) with complementary beneficial properties, is discussed as a strategy to increase the efficiency and the flexibility of BS-based crop production strategies under variable environmental conditions. Moreover, MCP application aims at the restoration of plant-beneficial, soil biological processes disturbed by soil degradation and intensive use of agro-chemicals. This PhD thesis was initiated to characterize the modes of action and the potential advantages of a representative commercial MCP formulation over selected single strain PGPM inoculants, with documented effects on plant growth promotion and pathogen suppression. In total, nine pot and field experiments were conducted with three crops (maize, spring wheat, tomato) on seven different soils with three organic and inorganic fertilization regimes. Only in one out of nine experiments conducted in this thesis, clear evidence for superior MCP performance was detectable in a drip-irrigated tomato field experiment conducted under the challenging environmental conditions of the Negev desert in Israel (Bradáčová et al., 2019c). This finding demonstrates that MCP inoculants can exhibit an advantage over single strain inoculants but not as a general feature. Selective interactions with the type and dosage of the selected fertilizers, as well as avoidance of inhibitory effects on root growth during MCP rhizosphere establishment, have been identified as critical factors. A further characterization of the conditions, promoting beneficial plant-MCP interactions is mandatory for a more targeted and reproducible MCP application.
The importance of soil microorganisms and cover crops for copper remediation in vineyards
(2014) Mackie, Kathleen; Kandeler, Ellen
The historical use of copper fungicides, as a plant protection agent, has moderately polluted agricultural topsoils across Europe. Organic agriculture, in particular, continues to be limited to the use of copper fungicides due to a lack of permitted alternative plant protection agents. In recent years, the effects of copper accumulation in the soil have been observed. Studies on the negative effects of copper in agricultural soils show a decrease in ecosystem services, which rely on macro- and micro-organisms. Thus, there is the question of how to remediate copper polluted crop fields. Although this topic has more recently been investigated in the laboratory, currently, there are no experiments available in the field. Viticulture is one of the largest perennial crops in Europe that utilize copper fungicides. Therefore, this dissertation was designed to investigate copper remediation strategies in vineyards, in order to best understand potential solutions for a growing problem, as well as their effect on ecosystem services. Understanding the reaction of and support by soil microorganisms will help determine which strategy has the best potential. The main project was implemented using two field experiments, each of which analyzed copper availability, microbial abundance, function and community composition to determine the overall outcome of copper remediation. The dissertation is presented in four papers. The first paper is a review on copper in vineyards, which focused specifically on cutting-edge remediation strategies currently being studied. This paper also provided information on knowledge gaps in the literature. The second paper showed the spatial distribution of copper and soil microorganisms at the plot scale, providing a better understanding of copper and microbial distribution as well as a foundation for subsequent papers. The third paper analyzed copper phytoextraction by single species and mixed species cover crop plots and the microbial community that may support it. The fourth paper was aimed at observing the ability of biochar and biochar-compost to immobilize copper and improve ecosystem services. The studies utilized classic soil biological methods (enzyme activities, microbial C and N, ergosterol) and modern molecular techniques (quantitative polymerase chain reaction (qPCR) of 16S rRNA and taxa specific bacteria genes and phospholipid fatty acid analysis (PLFA)) as well as determination of chemical soil properties and copper fractions.