CALDECOTT AND NORTH: RADIO-SENSITIVITY OF SEEDS 



379 



stored for 120 hours at —78° C. They were then removed from this 

 temperature and subjected to additional storage periods, at either 

 20° C or 85° C, before being hydrated (Figure 11B). 



100 



A. 

 Stored immediotely ofter 75O0r of x-rays ot either 20*C. 

 or 85°C before hydration 



20*C ♦ anaerobic hydration 



24 30 



TIME STORED (HRS.) 



Figure 11. — The effect of post-irradiation temperature on X-ray-induced 

 storage injury and the suppression of injury progression by low tempera- 

 ture. 



These data clearly show that, for at least the first few hours, 

 at both 20° C and 85° C injury increases progressively as a function 

 of time stored, with the most rapid increase occurring at the highest 

 temperature. Furthermore, they show that sensitivity to hydration 

 in the presence of oxygen is eliminated first by the highest temper- 

 ature. In addition, they demonstrate that after about 48 hours storage 

 at 85° C there is a partial recovery from injury. Essentially the same 

 result was obtained when seeds were stored at 75° C for longer periods 

 of time (Figure 12). 



The data also demonstrate (16) that storing seeds at —78° C for 

 120 hours essentially prevents the progression of post-irradiation 



