Erinevate kasvatustehnoloogiate mõju Fusarium spp. esinemisele ja mükotoksiinide tekkimisele teraviljadel

A Thesis for applying for the degree of Doctor of Philosophy in Agriculture.Microbiological and toxicological purity are important one indicators of the quality of cereals. Albeit the content of fusariosis and mycotoxins in the food cereals is not permitted, the feed grain may contain 0.1% Fusarium spp. grains and the levels of mycotoxins may not exceed the maximum levels established in the European Union. Earlier, in 1973–1992, the monitoring of cereal yields conducted by Lõiveke Heino showed that more than 79% of the samples contained grains infected with Fusarium fungi, and on average 54% of the samples monitored in 1998–2007 were infected with mycotoxins in Estonia. The results of several countries scientific studies show that agronomic techniques such as crop rotation, cultivation technology, fertilization, pesticide use, as well as the type and variety of cereals and weather conditions affect the spread of Fusarium fungi under field conditions and the formation of mycotoxins in grains. Until now, there was a lack of knowledge about the extent to which the cultivation technologies affect the Fusarium infestation and mycotoxin contamination of cereals in the Northern Baltic region. Thus, the following hypotheses were set in this dissertation: 1) that the use of barley-pea intercropping technology would reduce the infestation of Fusarium fungi on grain; 2) that the nitrogen fertilization of spring barley would increase the abundance of moulds, yeasts and Fusarium fungi on the grain; 3) the spraying with fungicide in flowering time reduce the incidence of Fusarium fungi, and the formation of mycotoxins DON, HT-2 and T-2 in the barley grains; 4) that the capacity of Fusarium spp. to produce mycotoxins depend on the available carbon and nitrogen sources and affected by environmental conditions. The results of this dissertation showed that the location of the field, the cultivation technology and the weather had a very strong effect on the occurrence of moulds, including Fusarium fungi, on cereals grains. However, the environment and the structure of carbon and nitrogen affected the formation of mycotoxins in the grains. Thus, the suitable cereal growing technologies enable to reduce the contamination of cereals with Fusarium fungi and mycotoxins in the northern climate conditions.Teraviljade kvaliteedi olulisteks näitajateks on teiste hulgas ka mikrobioloogiline ja toksikoloogiline puhtus. Kui toiduviljas ei ole fusarioossete seente ja mükotoksiinide sisaldus lubatud, siis söödavili võib sisaldada 0,1% fusariooseid teri, kuid mükotoksiinide sisaldus ei tohi ületada Euroopa Liidus kehtestatud maksimaalseid piirmäärasid. Varasemalt, aastatel 1973–1992, Lõiveke Heino poolt Eestis läbi viidud teraviljade saagi monitooring näitas, et üle 79% proovides esines Fusarium seentega nakatunud terasid ning aastatel 1998–2007 monitooritud teraviljast oli mükotoksiinidega saastunud keskmiselt 54% proovidest. Teistes riikides tehtud teadusuuringute tulemused näitavad, et agronoomilised võtted, nagu külvikord, harimistehnoloogia, väetamine, pestitsiidide kasutamine, aga samuti teravilja liik ja sort ning ilmastikutingimused, mõjutavad olulisel määral Fusarium seente levimist ja mükotoksiinide tekkimist teradesse. Siiani puudusid Põhja-Baltikumi piirkonda sobivad teadmised kui olulisel määral meie agroklimaatilistes tingimustes kasvatustehnoloogilised võtted mõjutavad teraviljade Fusarium seentega nakatumist ja mükotoksiinidega saastumist. Seega seati käesolevas doktoritöös järgmised hüpoteesid: 1) odra-herne segukülvi tehnoloogia kasutamine võimaldab vähendada terade Fusarium seentega nakatumist; 2) ilmastik, põllu asukoht ja taimedele antud lämmastiku kogused mõjutavad oluliselt hallitus-, pärmseente ja Fusarium seente arvukust teradel; 3) teravilja õitsemiseaegne pritsimine fungitsiidiga vähendab Fusarium seente esinemist ja vähendab mükotoksiinide DON, HT2 ja T2 tekkimist teradesse; 4) Fusarium seente mükotoksiinide tootmine on mõjutatud keskkonna tingimustest ja süsiniku ning lämmastiku päritolust. Doktoritöö tulemustest selgus, et põllu asukoht, kasvatustehnoloogia ja ilmastik avaldasid väga tugevat mõju hallitusseente, sealhulgas Fusarium spp. esinemisele teradel. Kuid mükotoksiinide tekkimine teradesse oli seotud ilmastikuga, keskkonna happesusega ja selles oleva süsiniku ning lämmastiku struktuuriga. Seega Põhjamaade ilmastikku sobiva teravilja kasvatustehnoloogia valikuga on võimalik vähendada saagi saastumist Fusarium seentega ja mükotoksiinidega.Publication of this thesis is supported by the Estonian University of Life Sciences

Effects of lake sediment on soil chemical composition, dehydrogenase activity and grain yield and quality in organic oats and spring barley succession

In organic farming, it is important to maintain soil fertility with organic fertilisers; often organic compost, manure, or slurry is used. However, the effects of lake sediment in maintaining and improving soil fertility are less studied. The direct and residual effects of a one-time application of 50 t ha-1 or 100 t ha-1 of lake sediment were compared to an unfertilised control for oats (Avena sativa) (2015) followed by spring barley (Hordeum vulgare) in 2016, under organic farming conditions. Soil chemical composition, microbial activity in the 0–20 cm soil layer, grain yield, and grain quality were tested. The application rate, 100 t ha-1 , increased (P < 0.05) the soil organic carbon (SOC), the amount of mobile calcium (Ca), total nitrogen (Ntot), and boron (B) content in soil. Both application rates increased (P < 0.05) the amount of magnesium (Mg), copper (Cu), and manganese (Mn) content in the soil. The application rate had no effect on soil pH. Soil dehydrogenase activity (DHA) was higher (P < 0.05) at 100 t ha-1 than the control and the lower application rate. Both rates of lake sediment application significantly (P < 0.05) increased the grain yield and test weight for oats in 2015. Positive residual effects on spring barely yield only occurred in the 100 t ha-1 treatments in 2016. No residual impact of lake sediment was found on spring barely quality