*3.3. DON Contamination*

The variety specific data (Table 7) show a similar picture to the FDK data. The four isolates showed larger aggressiveness differences, and their combinations showed rather variable performance, depending on their combinations (Table 7A). It seems the mixing resulted in both a decreasing of the aggressiveness level of the most aggressive Fg 19.42 isolate and in a reduction of DON contamination; and this tendency was true not only for DON but also for DI and FDK. On the other hand, it is also true that the aggressiveness of the mixture was, in most cases, significantly higher than the arithmetical means of the mixtures measured by the performance of the DON contamination original of the participating inocula. The isolates and isolate combinations of the low pathogenic isolates showed normally low aggressiveness and low DON levels, indicating that the use of such isolates does not give suitable inoculum for inoculation. The correlations between cultivars against the 15 different inocula (Table 7B, *n* = 15) to the used inocula (individual and mixed), as well as mixed inocula, were highly significant between r = 0.81–0.95. Here, also, the correlations between the means across cultivars and individual performances were given. These were higher, between r = 0.90 and 0.98 than that of the numbers between cultivars. The conclusion is that the means are better resistance indicators than any of the isolates and their mixtures present.

**Table 7.** Response of the wheat cultivars to the different isolates and their mixtures. DON data (mg/kg) across experiments, Szeged, 2013–2015.



The resistance expression di ffers in the 15 inocula. The genotypes that did not di ffer significantly to a given inoculum having lower di fferences than the LSD 5% is (Table 7A). In twelve cases, GK Garaboly is significantly more susceptible than GK Csillag and GK <sup>F</sup>ény. The more resistant GK Futár has higher DON contamination to GK Garaboly only in one case. GK Csillag shows lower DON contamination in seven cases than GK <sup>F</sup>ény, and in five cases, the GK <sup>F</sup>ény produces less DON. The di fference for mean does not reach the significance. This is all independent from the inoculum, should it be pure isolate or mixture. It can be stated, also, that the large resistance di fferences have the highest chances to be significant, except in the three cases without significant deviation. At lower resistance di fferences even otherwise significant di fferences cannot be demonstrated as the data show at di fferent inocula compared with the man cultivar reaction (Table 7A)

At two inocula, the cultivars did not show any significant di fference. This is true, also, for the control that had natural infection. The DON contamination of the naturally infected heads was low compared to the artificially inoculated samples. On the other side, they are not without risk, as they were higher than the EU limit of 1.25 mg/kg. Four inocula showed three not di ffering genotypes. Six inocula could not di fferentiate between two genotypes, and in two cases, every genotype di ffered from the other. This was the case also for the means. Counting the correlations (Table 7C), being significant, 30 cases were found of the 105 total correlations between inocula. The control values correlated with inocula only in one case. In 24 cases, the Isolate 3 and its combinations showed significant correlations, for the other possibilities we had only six cases. The question is, again, what is the best inoculum? It seems that mixed inocula are not better than the single spore lines are. We have chances for good or very good di fferentiation at the highest aggressive inocula, but not in every case. For demonstrating no significant di fferences, we have a chance at low aggressiveness. One solid conclusion is clear. There is no proof that mixtures would be better than pure isolates. However, we should have more inocula than one to present more useful results for a QTL phenotyping or a registration trial. Since, for us, the DON reaction is the most important, we provide the data for it in Figure 2.

**Figure 2.** Influence of mixing isolates on the resistance expression of the four cultivars with di ffering FHB resistance. DON contamination across years and experiments. LSD 5% between any bars in the figure is 18.71.

There are large di fferences between experiments (Table 8). The epidemic conditions in 2015 significantly increased the DON contamination; even the FHB and FDK values did not predict these high DON data values (Table 8A). The correlations with the 2014 data and other experiments were moderate, whereas, the others were highly significant with a correlation of r = 0.90 and above (Table 8B). The data also prove that a low aggressiveness level does not allow a proper distinction between the

effects of di fferent inocula. As one year does not give well-balanced results, in spite of the higher number of isolates, the tests in di fferent years have a high importance. The correlations between the four experiments were tested (Table 8C). Moreover, 89 cases from the 120 significant relations were registered. This shows a rather good agreemen<sup>t</sup> between responses of di fferent experiments. It should be noted that the control values correlated at a high ratio with the artificial inoculation data. For DI 52 and FDK 57, significant correlations were found. It seems that the best correlation matrix was found for DON.



The variance analyses (Table 9) revealed large similarities between the di fferent traits (Table 9A). The three-way interactions were not significant, so an additional F test to the "Within" category was not necessary. All main e ffects were highly significant. It is more important that the interactions were much smaller than the individual main e ffects were (Table 9B). This is significant in all cases in di fferences between the main e ffect and interactions for FHB and FDK. The variety e ffect against A × B is not significant for DON indicating that the main e ffect is more impressionable than the FHB or FDK are. The genotype (A) e ffect is significant over A × C interaction, indicating a good stability of resistance.


**Table 9.** Response of wheat to the different isolates and their mixtures. ANOVAs for the three traits, FHB, FDK and DON, Szeged, 2013–2015.
