*2.1. Field Experiments*

Thirty cultivars of winter wheat (*Triticum aestivum* L.) were evaluated (Table 1). The cultivars were listed in the Polish National List of the Research Centre for Cultivar Testing (COBORU) and were added to the list between 1998 ('Mewa') and 2009 ('Belenus'). The cultivars were described in detail in the paper of Góral et al. [20]. They di ffered in the pedigree, morphological characters, and resistance to Fusarium head blight (FHB). Cultivars were grouped in four classes of FHB resistance: susceptible (S), medium susceptible (MS), medium resistant (MR), and resistant (R).


**Table 1.** List of winter wheat cultivars used in this study.

\* Group of resistance to Fusarium head blight [20]; S = susceptible, MS = medium susceptible, MR = medium resistant, R = resistant.

Field experiments were established in 2014 in the experimental fields of state-owned research institute—Plant Breeding and Acclimatization Institute (IHAR-PIB) in Radzików, Central Poland. First experiment was sown in the conventional field (GPS coordinates: 52.212517, 20.634765). Pre-crop was oilseed rape. Artificial fertilizers were applied according to standard agricultural practices in IHAR-PIB in particular. In the autumn 3 dt ha−<sup>1</sup> of 'Polifoska 6 fertilizer was applied (N—18 kg ha−1, P—45 kg ha−1, K—72 kg ha−1). In the spring, after the start of vegetation ammonium nitrate fertilizer was applied in an amount providing 68 kg N ha−1. Weeds and pests were controlled with herbicides and insecticides. Immediately after sowing weeds were controlled with herbicide 'Maraton 375SC' in a dose of 4 L ha−1. In spring weeds were controlled using the herbicide 'Attribut 70GS' in a dose of 60 mg ha−1. Cereal leaf beetle and aphids were controlled with 'Fastac Active 050ME' in a dose of 250 mL ha−1. No fungicides were applied.

Simultaneously the same wheat cultivars were sown in the experimental organic field of IHAR-PIB (GPS coordinates: 52.216319, 20.638653). Wheat was grown according to organic farming practices with no chemical disease control and application of fertilizers. Pre-crop was pea. Weeds were controlled mechanically. No fertilizers or other components allowed in organic farming were applied. Distance between two experimental fields was about 500 m. Single plot size in both experiments was 5 m2. In both fields, cultivars were sown in three randomized blocks (replications) distant from each other by 2 m.

Heading and full flowering dates for individual plots were recorded. Plant height was measured after the end of heading stage. Fusarium head blight was scored based on the mean percentage of blighted spikelets per infected head (disease severity) and the percentage of infected heads per plot (disease incidence). Fusarium head blight index (FHBi) was calculated as the combination of disease severity and disease incidence.

$$\text{FHB}\_{\text{i}} = \left(\text{FHB}\_{\text{severity}} \times \text{FHB}\_{\text{Irricidence}}\right) / 100 \tag{1}$$

Presence of other fungal diseases were also recorded. They were as follows: yellow rust (*Puccinia striiformis*), leaf rust (*P. triticina*), Septoria tritici blotch (*Zymoseptoria tritici*), Stagonospora nodorum blotch (*Parastagonospora nodorum*) and tan spot (*Pyrenophora tritici-repentis*). These diseases were scored according to percentage of leaf area per plot with symptoms of disease—necrosis and/or sporulation.

### *2.2. Analysis of Mineral Elements in Soil*

In spring, soil samples were collected from conventional and organic fields. Twenty soil cores were taken from experimental plots in both fields using soil sampler. Soil cores from plots were mixed thoroughly.

The material was mineralized with a CEM Mars 5 Xpress (CEM, Matthews, NC, USA) microwave mineralization system (55 mL vessels) using 8 mL HNO3 (65%) and 2 mL H2O2, according to the program comprising three stages: First stage—power 800 W, time 10 min, temperature 120 ◦C; second stage-power 1600 W, time 10 min, temperature 160 ◦C; third stage-power 1600 W, time 10 min, temperature 200 ◦C [21]. Materials after digestion were filtered through 45 mm filters (Qualitative Filter Papers Whatman, Grade 595: 4–7 μm; GE Healthcare, Buckinghamshire, UK), and filtrate completed with deionized water from Milli-Q Academic System (non-TOC (Total Organic Carbon); Millipores. A.S., Molsheim, France) to a final volume of 50 mL. Concentration of particular trace elements was analyzed by the flame atomic absorption spectrometry (Cd, Cu, Mn, Cr, Co, Si, Ni, and Zn), atomic emission spectrometry (Mg, Ca, Na, K, B) using an AA Duo—AA280FS/AA280Z spectrometer (Agilent Technologies, Mulgrave, Victoria, Australia), equipped with a Varian hollow-cathode lamp (HCL; Varian, Mulgrave, Victoria, Australia). Calibration curves were prepared in four replicates per each trace element concentration. Detection limit for the analyzed metals was, mg kg−1: Ca 0.015, Na 0.10, K 0.09, Mg 0.003, B 0.06, Cu 0.18, Zn 0.06, Cr 0.005, Mn 0.005, Co 0.011, Si 0.12, Ni 0.005, Cd 0.01.
