W. D. JACKSON 



also in the series storage without irradiation, storage with irradiation, and 

 storage with irradiation and additional post-storage. These trends are shown 

 in Table 1. 



Table 1. Chromosome breaks induced in pre- and post-irradiation storage in various 

 oxygen-nitrogen mixtures — Mean and standard error of chromosome breaks per cell 

 (x + S.E.), and mean index of dispersion for these chromosome breaks (r'.v/.v + S.E.) — • 

 Comparisons are shown of the Fits between the Sum Data, the Sum Poisson and Sum 

 Negative Binomial fitted individually to the distributions for each root 



The leaching experiment, although merely a preliminary to a larger 

 experiment, is interesting in the light of the above evidence. However, 

 because of the lack of statistical control and the inefficient design, the results 

 must be viewed with caution. The results of the leaching experiment are 

 shown in Figure 9. The leachate from unirradiated fresh seed slowed ger- 

 mination of the test seed but produced no increase in the breakage of the 

 chromosomes. However, the leachate from irradiated fresh seed increased 

 chromosome breakage in the test seeds by a factor of 2 • 5 (significant at the 

 0-005 level). The leachate from unirradiated aged seed produced a high, 

 but variable amount of breakage in the test seed. The mean breakage level 



199 



