Improvement of the resistance was observed in F₁ generation in comparison with relative parental components (i.e. sources of resistance). This was particularly evident in the following combinations: (Toropi x Encruzilhada), (Bizel x Mironovskaya 808), (Bizel x Poncheau) and (Balayacerkov x Poncheau), the resistance level of which ranged from 0,75 (Toropi x Encruzilhada) to 1,04 (Balayacerkov x Poncheau). In the presented combinations in F₁ generation of single crosses there is obviously additive gene effect present. Additive gene effect and the more expressed level of resistance particularly appeared in crosses with Bizel, Poncheau and Encruzilhada, where as somewhat less in combinations involving genotypes Mironovskaya 808, Toropi and Balayacerkov. Reaction type of crosses was resistant (R).

Furthermore, partial dominance was also noticed in combinations of crosses such as: (Roazon x Poncheau), (Roazon x Mironovskaya 808) and (Roazon x Bizel), which expressed the level of resistance from 2,59 (Roazon x Poncheau) to 3,33 (Roazon x Bizel). Partial dominance is present in those combinations involving genotypes with less expressed level of resistance, in this case crosses with Roazon. Reaciton type of crosses was moderately resistant to moderately susceptible (MR - MS).

Even more expressed improvement of the level of resistance in comparison to parental components was found in F₁ generation of double crosses (F₁ x F₁), in which the level of resistance ranged from 0,50 /(Roazon x Mironovskaya 808) x (Balayacerkov x Poncheau)/ to 1,66 / (Bizel x Poncheau) x (Toropi x Encruzilhada)/. Increased level of resistance was also expressed in the following combinations of double crosses (F₁ x F₁); /(Roazon x Bizel) x (Bizel x Poncheau) /, /(Bizel x Mironovskaya 808) x (Balayacerkov x Poncheau) /, as well as in /(Roazan x Poncheau) x (Bizel x Poncheau)/. These crosses expressed the resistant (R) type of reaction.

From all said above probably the polygenic mode of inheritance with its minor gene effects is present here.

The results given in Table 1 prove that among all wheat sources of resistance to fusarium head scab, the highest level of resistance was found in genotypes Encruzilhada, Bizel, Poncheau and Mironovskaya 808. In connection with the investigations of the level of resistance to fusarium head scab similar findings were reported also by other workers (Schroder and Christensen 1963; Feekes and Wieten 1967; Wildermuth and Purss 1971; Luzzardi et al 1974, 1975, 1984; Mesterhazy 1977, 1978, 1983; Saur and Trottet 1981; Saur, 1984; Bekele 1984; Liu 1984; Milatovic, Vlahovic and Tomasovic 1982; Tomasovic 1981, 1984).Conclusions

Based on several investigations of wheat sources of resistance to fusarium head scab under artificial field infection, we might have the following conclusions:

1. A considerable difference in the level of resistance among the selected genotypes was found, ranging from 0,65 to 3,89 (rating scale 0 - 5).

2. Testing of resistance in adult stage has revealed the improvement of the level of resistance in F₁ progenies as well as in F₁ x F₁ crosses in comparison with their parental components.

3. Additive gene effect is noticed in F₁ including increased level of resistance as well as partial donimance.

4. Those combinations involving genotypes Bizel and Poncheau, shows the highest level of resistance whether it was in F₁ generation or in F₁ x F₁ crosses.

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