Sirvi Autor "Loit, Kaire" järgi
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Kirje The indigenous arbuscular mycorrhizal fungal colonisation potential in potato roots is affected by agricultural treatments(2018) Loit, Kaire; Soonvald, Liina; Kukk, M.; Astover, Alar; Runno-Paurson, Eve; Kaart, Tanel; Öpik, Maarja; Estonian University of Life Sciences. Chair of Plant Health; Estonian University of Life Sciences. Chair of Soil Science; Estonian University of Life Sciences. Chair of Crop Science and Plant Biology; Estonian University of Life Sciences. Chair of Animal Breeding and BiotechnologyThere is an urgent need to develop novel approaches to enhance sustainable agriculture while not reducing cr op yields. Arbuscular mycorrhizal (AM) fungi establish symbiotic associations with most crop plants improving plant performance and soil health. This study investigated the extent of colonisation of potato roots by indigenous AM fungi in the arable soil under conventional and organic farming systems. Potato roots had greater AM fungal colonisation levels under organic than conventional farming, though in general, root colonisation levels were extremely low in both farming systems . Pota to root AM fungal colonisation was lower with higher soil P content and higher with higher annual C input. Trap plant root AM fungal colonisation was considerably higher than in field potato roots and showed that soil mycorrhizal inoculum potential was hig her in organic than in conventional farming. Thus, the positive impact of manure application in organic fields to the potato AM fungal colonisation can be explained by previous higher total annual C fresh organic matter input and lower soil P content under treatment. Furthermore, the natural AM fungal abundance in the soil was sufficient to colonise trap plant roots, suggesting a low mycorrhizal dependence of the studied potato cultivar.Kirje Pathogenic and arbuscular mycorrhizal fungi in potato fields in Estonia(Eesti Maaülikool, 2021) Loit, Kaire; Astover, Alar (advisor); Tedersoo, Leho (advisor); Öpik, Maarja (advisor); Timonen, Sari (opponent); Koppel, Mati (reviewer)Soil fungi have fundamental ecological roles as decomposers, mutualists, and pathogens of plants. Roots of agricultural plants are hosts for various microorganisms. These include many harmful, often soilborne, pathogens, as well as beneficial organisms such as plant growth- and health‐promoting arbuscular mycorrhizal (AM) fungi. Potato (Solanum tuberosum L.) yield and quality is very sensitive to various pathogens. Soils contain distinct AM fungal communities and most crops (including potato) naturally become colonized by AM fungi in the absence of inoculation. In the current thesis, diversity, abundance, and community composition of putative pathogenic fungi and symbiotic AM fungi in potato fields in Estonia is studied. We found that potato roots have higher AM fungal colonization levels under organic, rather than conventional, farming. However, colonization of potato roots by AM fungi is extremely low in both of these management types. Relative abundance of AM fungi is significantly higher at the end of the growing season compared to the beginning. Seasonal and cultivar-driven changes of soilborne phytopathogenic fungal communities in conventional potato production, both within roots and in soil, were studied for the first time on a large number of potato cultivars using high-throughput sequencing. Cultivar influenced root-pathogenic fungal richness and community composition more than sampling time or sampling time x cultivar interaction. Additionally, cultivar had a significant effect on root fungal pathogen relative abundance. In soil, the community composition of putative pathogenic fungi changed significantly over time. Under increasing threat of plant disease outbreaks, the speed of detection of plant disease agents is essential for avoiding large-scale crop losses. This thesis work demonstrated that the third-generation sequencing device MinION is well suited for rapid, PCR-free diagnosis of fungal pathogens and other eukaryotic organisms. However, care should be taken due to a number of possible limitations that might lead to misdiagnosis. Our findings demonstrate that AM fungi are present in Estonian conventional potato fields, but studied potato cultivars exhibit low AM root colonization levels. In order to benefit from AM fungi in potato cultivation, a potato growing technique that involves less soil disturbance could be used. The results of this thesis work also indicate the importance of plant breeding, concerning disease resistance; and offer implications for rapid pathogen diagnostics that may help to avoid large-scale crop losses caused by new, emerging pathogens that are undetectable from symptoms.Kirje Physiological disorders affect apple susceptibility to Penicillium expansum infection and increase probability for mycotoxin patulin occurrence in apple juice(2019) Heinmaa, Lagle; Põldma, Priit; Loit, Kaire; Kiiker, Riinu; Moor, Ulvi; Estonian University of Life Sciences. Institute of Agricultural and Environmental Sciences. Chair of Horticulture; Estonian University of Life Sciences. Institute of Agricultural and Environmental Sciences. Chair of Plant HealthPenicillium expansum infection of apples and mycotoxin patulin (PAT) production has previously been associated with many pre- and postharvest factors other than physiological disorders. In the current study, ‘Antei’ and ‘Krameri tuviõun’ apples with and without bitter pit (BP) symptoms and ‘Talvenauding’ apples with and without superficial scald (SS) symptoms were used in order to determine if the named physiological disorders may influence susceptibility to P. expansum infection and PAT production. Apples were inoculated with 10 μL P. expansum spore suspension with the concentration of 1×105 conidia mL-1 and stored at 24 °C with relative humidity (RH) 80%. After 7 and 11 days, lesion diameters were measured, and apples were pressed into juice. PAT content was determined in pasteurized juice. Two cultivars out of three showed that in fruit with physiological disorders, Penicilllium infection and PAT production proceeded significantly faster compared to apples, which did not have physiological disorders. SS increased the risk for PAT occurrence in juice more than BP: while the juice pressed from BP–affected apples with no visual signs of fungal diseases did not contain PAT, juice pressed from apples with SS contained PAT three times above legislative limits defined by the World Health Organization (50 μg L-1).Kirje Terve loom ja tervislik toit : konverentsi "Terve loom ja tervislik toit 2021" stendiettekanded(Eesti Maaülikool, 2021) Nahkur, Esta; Andrianov, Vladimir; Namm, Aimar; Torga, Taavi; Arend, Andres; Aunapuu, Marina; Olt, Andres; Loit, Kaire; Puidet, Britt; Püssa, Tõnu; Riisberg, Märt; Ots, Meelis; Sild, Erkki; Marcone, Giovanni; Kaart, Tanel; Piirsalu, Peep; Arney, David Richard; Carnovale, Francesca; Jin, Xiao; Descovich, Kris; Guo, Wenliang; Shi, Binlin; Phillips, Clive J.C.; Kass, Marko; Haskell, Marie; Kuus, Kaisa; Mäesaar, Mihkel; Roasto, Mati; Koskar, Julia; Anton, Dea; Raudsepp, Piret; Meremäe, Kadrin; Kramarenko, Toomas; Rusalepp, Linda; Rätsep, Reelika; Kaldmäe, Hedi; Bleive, Uko; Tedersoo, TriinEsta Nahkur, Vladimir Andrianov, Aimar Namm, Taavi Torga, Andres Arend, Marina Aunapuu. Luude vaagnapõhja mineraalne tihedus lehmadel.