THF- I.IFF.-SPAX OF MU'FAGFA'S I'KODUCFD IN CRLLS l<^ IKKADIA HON 



after irradiation, breakage increases. These results are plotted in Figure 5, 

 with the results of the experiments withoiii post-storage for comparison. 

 The increase at low oxygen concentration is marked. As before, this total 



20 

 7. 02- 



100 



-1A days pre -irradiation storage 



Figure 3. Frequency of chromosome breaks per cell in seed germinated 



immediately after irradiation in various oxygen-nitrogen mixtures and 



pre-storage for two weeks in these atmospheres (1-2 kr X irradiation) 



effect may be partitioned into its various components and this is shown in 

 Figure 6. The direct effect of irradiation and the direct effect of oxygen can 

 be deducted. This leaves a large component made up of the interaction 



02effect 



direct action irradiation effed 



20 100 



% O2 — ►Kdays pre- irradiation storage 



Figure 4. Partition of the total irradiation-oxygen damage shown in Figure 3 



between irradiation and oxygen previously shown in Figure 4 and a post- 

 storage oxygen effect (shaded area in Figure 6), which is again zero in 

 nitrogen but which rises to full effect in 20 per cent oxygen concentration. 



196 



