Nov. i, 1920 



Effect of Drying Disinfected Seed Wheat 



241 



Three sorghums, Brown durra, Honey sorgo, and Sudan grass, were 

 found to be uninjured by either a 0.1 per cent or a 0.2 per cent solution 

 of formaldehyde even after weeks of drying. When the seed was stored 

 dry in the same manner as was the severely injured wheat, no effects of 

 the treatment ever appeared. This probably is due to protection af- 

 forded by the glumes in some instances, and in others by the thick seed 

 coats. 



PREVENTION OF POST-TREATMENT INJURY RESULTING FROM 



DRYING 



McAlpine (11) thought that soaking the seed which had been held 

 some time before sowing prevented the appearance of formaldehyde in- 

 jury, but neither Darnell-Smith and Carne (5) nor Kiessling (9) was 

 able to confirm this. The writer also has been unable to show that the 

 injury can be avoided in this way. Soaking the seed hastened the 

 germination, as it always does even with untreated wheat. But the 

 characteristic injury to the seedling remained, and the percentage of 

 germination, although occasionally somewhat augmented, was far from 

 normal. It seems probable, therefore, that the hardening of the pericarp 

 is not the primary injury. 



It has been shown in this paper that thorough aeration of the treated 

 seed as it dries retards and lessens storage injury but does not always 

 prevent it (Tables X, XI, and XII). Neither is rapid drying possible 

 where large quantities of wheat are handled. However, it was found 

 that dry-storage injury can be entirely avoided by simply washing the 

 seed with water after treatment (PI. 41). The extent to which this 

 simple procedure would do away with the danger in the use of formalde- 

 hyde solutions is shown by the data in Table XVI. 



Table XVI. — Percentage of germination of wheat treated with o.l and 0.2 per cent 

 formaldehyde solutions and washed with water, compared with percentage of germina- 

 tion of unwashed samples 



Length of drying period. 



Days 

 O 



7 



14 



30 



60 



0.1 per cent solution. 



Seed not 



washed in 



water. 



78 

 62 



58 



5 2 

 36 



Seed 



washed in 



water. 



78 

 74 



74 



74 



0.2 per cent solution. 



Seed not 



washed in 



water. 



72 



So 

 30 



3 2 



Seed 



washed in 



water. 



76 



74 

 82 

 76 

 72 



Control, un- 

 treated." 



70 

 72 

 76 

 72 

 74 



"This seed had been injured by fumigation with carbon bisulfid, hence the low germination of the 

 untreated control and washed samples. 



9507°— 20 6 



