| Changes in rust susceptibility due to partial irradiation
of wheat seedlings and its dose dependence K. KATSUYA National Institute of Genetics, Misima, Japan The stems and leaves of seedlings at leaf stage of Triticum vulgare (Norin No. 16) were irradiated by X-rays at 5 kr. The seedlings were inoculated 10 days after irradiation by spraying with an aqueous uredospore suspension of Puccinia triticina. The first leaves of the seedlings were removed 10 days after inoculation and the size of uredosori was measured. They were on plants whose whole bodies or stems were irradiated about 1.7 times larger than on the control and plants whose leaves only were irradiated. Seedlings at 2 leaf stage of T. vulgare (Norin No. 50) were irradiated by gamma - rays, at 0.1, 0.25, 0.5, 1, 2.5, 5 and 10 kr. The seedlings were inoculated 6 days after irradiation by spraying with the spore suspension. Seedling length was measured 7 days after irradiation, and then the size of the sori was measured 12 days after inoculation. Inhibition of seedling growth increased with the increase of dosage and the seedling length at dosage above 1 kr remained unchanged. Also, the size of the sori increased with the increase of the dosage, however it did not further increase of dosages above 5 kr. |