[en] A revolving facility was made for the homogeneous superficial irradiation of spherical vegetables and fruits (apricot, peach, tomato, apple, etc.) with fast electrons. After the building of the technological apparatus described in detail, dosimetrical measurements were carried out by a Van de Graff generator of 2 MV and it was proved, that the superficial irradiation had a smaller effect on the quality of the fresh fruits, than of the stored ones. The developed apparatus can be altered according to the ripe-rate of the products. (K.A.)

[en] Research carried out between 1971 and 1981 is summarized. Attempts to find induced mutants with full resistance to pathotype mixtures of the three pathogens were not successful. Reasons are discussed. Studies on wheat lines tolerant to stem rust infection led to the conclusion that this disease reaction may be often accompanied by a reduced number of infection sites and a longer lag period resulting in reduced spore production. Various selection methods have been evaluated. Selecting for the multigenic 'non race specific' way is promising. (author)

[en] Mutation for vertical mildew resistance did not seem to be promising under our environmental conditions. Occasionally, we detected moderately disease resistant types in the M₃ and M₄. However, the rate of mutations for moderate type of resistance for five diseases was indeed lower in the irradiated populations than in the non-irradiated ones. On the other hand, in the production of characters which used to be considered as non-progressive from an evolutionary point of view /e.g. dwarfness/, induced mutations seemed to be superior over spontaneous mutations. The usefulness of three methods for screening large mutant populations for race non-specific disease resistance, namely the Tolerance Test, the Multitolerance Test and the Center Pivot Method is discussed. Regarding the biochemical nature of rust resistance, we came to the conclusion that the so called common antigens correlate compatibility between the host and the pathogen only on a species level. However, the ''common antigen theory'' i.e. the occurrence or the lack of common antigenic proteins in host and pathogen does not offer an explanation for susceptibility or resistance, respectively on a cultivar level. (author). (author). (author)

No abstract available

[en] To develop an effective in vitro screening system for mutation breeding work, an appropriate screening agent and the method to utilize it are the fundamental components. In the present research, reaction of the host plants to necrotrophic pathogens were examined in relation to the comparable reaction to superoxide resistance. The research used Solanaceae crops (potato and tomato) as materials, and sensitivities to Phytophthora toxin were compared among cultivars. Differential sensitivities were observed between callus and root cap cells, the latter showed better reactions than the former to differentiate sensitive and resistant cultivars. (author). 7 refs, 1 tab

[en] Detached flag leaf cultures were not suitable for evaluation of stem-rust resistance in our screening programme. On the basis of yield evaluation it was possible to screen out ten stem-rust ''tolerant'' wheat lines in field experiments. Rusted and protected microplots of each line were paired within a replicate. After artificial inoculation, the protected plants were sprayed with fungicides (benomyl plus dithiocarbamate plus copper salt) at weekly intervals until maturation to keep each protected plot rust-free. The thousand-kernel weights of rusted and protected plots were compared. When the thousand-kernel weight of protected plot increased only slightly and the rust reaction type of plants was susceptible in the rusted plot, the line was screened out as putative ''tolerant''. On the basis of three-year field trial ten ''tolerant'' lines were selected. Nine out of ten lines proved to be resistant to two stem-rust races in greenhouse tests in the seedling stage, when resistance was determined on the basis of reduced spore production instead of infection types. Resistance of these seedlings related partly to the reduced number of pustules and partly to a slow rusting character of plants. It seems possible to screen resistant cultivars in the greenhouse by the method outlined in this paper, when resistance is determined on the basis of a reduced number of infection sites and/or by the slow rusting capacity. (author)