Abstract
Dormant seeds of Triticum monococcum flavescens were exposed to X- and γ-rays at the dosage of 10 and 20kr. Growth of seedlings, single spike fertility and chromosome aberrations of X1 plant and gene mutations in X2 were compared for acute and chronic irradiation. At acute irradiation with X- and γ-rays treatment was given either immediately before sowing or the irradiated seeds were kept for 30 days in storage at room temperature (about 20°C) or at 5°C. Also, the effect of β-radiation by 32P was examined for comparison.
The relation between the inhibition of seedling growth and dosage, temperature in storage and irradiation time coincides roughly with the relation between the percentage of induced sterility and all those conditions. X- and γ-irradiations were far more effective at 20kr than at 10kr. In the case of 30 day storage, γ-rays inhibited the growth of seedlings and reduced the fertility stronger than X-rays, while irradiation applied just before sowing showed the reverse relation. It was further observed, especially with γ-rays, that low temperature had the strongest inhibitory effect. At 10kr acute γ-irradiation was more effective than the chronic one, while at 20kr the reverse relation was observed.
The frequency of chromosome aberrations and gene mutations was strikingly higher at 20kr than at 10kr. Irradiation just before sowing and 30 day storage at low temperature were more effective than storage at room temperature fter irradiation. The effect of γ-irradiation was less.
The effects of β-irradiation were unexpectedly slight. It was found from another experiment with seed absorption of 32P solution that the actual dosage of β-rays was very low.
