Effects of accute gamma iradiation on plant development.1. Growth and survival of Avena fatua (L), Spergula arvensis(L) and Sinapis arvensis (L) irradiated at early stages ofdevelopment

Three different weed species, Avena fatua (L), Sinapis arvensis (L), and Sperqula arvensis (L), were cultivated inpots and treated by 60Co gamma rays at various early stages of development. Irradiation was applied on the 1st, 4th and 7th day after sowing. The doses were ca, 4.5, 9 and 18 krad for Avena and ca. 5.7, 12 and 23 krad for Spergula and Sinapis. In the case of Avena, irradiation was also performed at ca. 2.2, 4.5 and 6.7 krad on the 1st, 2nd and 4th day after sowing. Non irradiated pots served as control. The number of emerging and surviving seedlings was regularly recorded during the vegetation period and dropping seeds were collected. At the end of the experiment, the vegetative tissues and remaining seeds were harvested and studied. Depending on the time of treatment, irradiation affected the developing plants to a varying degree. In Avena, irradiation was found to strongly influence the development and seed production and particularly at higher doses, the plants were killed. Also in Spergula inhibition of growth and delay of flowering were recorded but no radiation-induced death or diminished seed production. Sinapis reacted only slightly, mainly by a dose-dependent delay in plant growth and in the development and ripening of the pods. The findings are discussed in the light of published results from experiments on irradiated seeds and on plants chronically irradiated in the field. (author)