376 



MUTATION AND PLANT BREEDING 



30- 

 20- 

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 30 



en 20 



Q 

 UJ 

 u 



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 m 



z 20- 



10 - 





 30 

 20-1 



10 



1 5,000r + aerobic hydration 

 x = 4.5 cm. 



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Ann 



£3- 



B. 



Heat * I5,000r ♦ aerobic hydration 

 x ■ 7.6 cm. 



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flu 



l5,000r + 48 hrs. storage 

 + aerobic hydration 

 x = 5.3 cm. 



n. 



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Heat + I5,000r + 48 hrs. storage 

 + aerobic hydration 

 x = 8.5 cm. 



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a 



I 



r 1 1 — 



10 II 12 13 14 15 



23456789 



SEEDLING HEIGHT (CM) 



Figure 8. — The effect of a 75° C pre-irradiation heat treatment on the 

 injury to seeds that are hydrated aerobically before and after storage. 



(Figure 8) or anaerobic hydration (Figure 9) the distribution of seed- 

 ling heights was more nearly normal in the populations that received 

 heat treatment than in the population that did not. Furthermore, the 

 most skewed distribution occurred in the populations that were not 



