Abstract
Using Triticum spelta, T. timopheevi, T. vulgare, and Oryza sativa, seedlings at 2 leaves were irradiated by X-rays or by gamma-rays, at 10, 30, 50 and 70kr. The seedlings were inoculated 1 and 7 days after irradiation by spraying with an aqueous uredospore suspension (Puccinia triticina 21 B), and the effects of radiation on the susceptibility to the leaf rust were observed. In seedlings of the same age, the first and second leaves were sampled, and the amounts of amino-nitrogen and reducing sugar were measured.
Effects of irradiation on leaf characters, namely stomata size, internal structure, viability, and sporulation of the fungus on the irradiated leaves were examined. Rust susceptibility of the irradiated plants (T. spelta and T. vulgare) was increased, as compared with the non-irradiated plants. In T. timopheevi which was inoculated 7 days after irradiation, the third leaf was susceptible, while the first and second leaves of the same plants were mostly resistant. The irradiated rice plants remained immune.
In T. timopheevi, the amount of amino-nitrogen was higher in the seedlings 1 day after irradiation, as compared with that of the non-irradiated seedlings, while it was lower 7 days after irradiation. The amount of reducing sugar increased seedlings 1 and 7 days after irradiation, in comparison with the non-irradiated seedlings. Stomata size and internal structure of the irradiated plants (T. spelta and T. vulgare) did not change noticeably, as compared with the non-irradiated plants.
Effects of irradiation on the viability of leaves were tested. When the growing point suffered radiation damages, the already developed leaves longer the remained fresh than those of the non-irradiated plants. The uredosori of the leaf rust produced on irradiated T. vulgare were larger than on normal plants. Relationships between rust susceptibility an irradiation await further experiments.
