*3.7. Multivariate Principal Component Analysis*

Multivariate principal component analysis showed significant di fference between two studied populations (wheat cultivars in two environments) in terms of FHB infection (Figure1). However, this di fference was caused by only some cultivars, which showed higher *Fusarium* infection (measured with di fferent parameters) in organic or conventional field. Cultivars from organic field had higher FHB index, proportion of dead seeds and *Fusarium* DNA content. In conventional field, the most infected cultivars had higher toxin content in the grain but moderate FHB index, dead seeds proportion and *Fusarium* biomass amount in kernels. The exception was cultivar 'Kampana' (C\_12) (Figure 2).

There were also carried out other tests—Multidimensional Wilks' Lambda test and Fisher distances test. They pointed to the significance of the separation between the analyzed growing systems at the significance level of *p* < 0.0001.

There was also compared which source of variation had higher e ffect on the obtained results (i.e., FHBi, DS, Total TCT B, Total TCT A, and *Fusarium* DNA concentration) using multivariate analysis of variance (MANOVA). Both sources statistically significantly a ffected the results; however, experimental variant (conventional vs organic field) had much higher significance (*p* < 0.0001). It means that Fusarium head blight infection and its e ffect on grain quality, toxins concentration and *Fusarium* biomass in kernels depended mainly on wheat growing environment. Resistance of cultivars to FHB was less important (*p* < 0.025).

**Figure 2.** Biplot of the principal component analysis for 30 winter wheat cultivars grown in conventional (C) and organic field (O). Two first components explained 55.90% of variability of Fusarium head blight index (FHBi), dead seeds proportion (DS), ergosterol (ERG) and type A (Total TCT A) and type B (Total TCT B) trichothecenes content, and concentration of DNA (*Fusarium* DNA) of five *Fusarium* species in grain. Samples from conventional field marked with circles and from organic field with triangles.

Cultivars grown in organic field were compared for their overall performance under such conditions with respect to resistance to *Fusarium* infection. Multivariable analysis (K-means, discriminant analysis) made it possible to divide cultivars into three groups depending on their resistance to head infection, number of dead seeds, accumulation of ergosterol and *Fusarium* toxins in the grain as well as contamination of grain with *Fusarium* fungi (Figure 3, Table 8).

The most infected five cultivars were in the second group (Figure 3, Table 9). They could be described by the highest FHB index, high number of dead seeds, high accumulation of *Fusarium* toxins and the highest concentration of *Fusarium* biomass in kernels. Only amount of ERG was medium in grains of the cultivars of the group 2. The other 25 cultivars were in two close groups 1 and 3. They mainly differed in amount of ERG in grain, which was the highest in the group 1 while the lowest in the group 3.

**Figure 3.** Discriminant analysis of 30 cultivars grown in organic field for Fusarium head blight index (FHBi), dead seeds proportion (DS), ergosterol (ERG), type A (Total TCT A) and type B (Total TCT B) trichothecenes content, and concentration of DNA of five *Fusarium* species in grain (*Fusarium* DNA): (**A**) Observations on the factor axes with marked groups 1–3; (**B**) Correlation circle.

μ μ The lowest overall infection showed cultivars from the group 3: 'Nateja', 'Mewa', and 'Markiza'. Regarding only accumulation of trichothecenes, it was the lowest in grain of 'Nateja' and 'Ostroga' from the group 3. It was low also in grain of cultivars 'Figura', 'Dorota', 'Mulan', 'Batuta', 'Tonacja' from the group 1, and surprisingly in grain of cultivar 'Belenus' from group of the most infected cultivars. Among the low-toxin accumulating cultivars, 'Ostroga', 'Batuta', 'Mulan', and 'Figura' were in the group of cultivars showing the highest grain yield per plot in organic field (Table S1). The lowest infected cultivar 'Nateja' had low grain yield caused by high yellow rust infection.


**Table 9.** Average values for groups shown in Figure 3A.
