6 



BULLETIN 916, U. S. DEPARTMENT OF AGRICULTURE. 



Serious injury was apparent in this experiment. Injury occurred to 

 five specimens of Triumph, six of Irish Cobbler, five of Spaulding 

 No. 4, four of American Giant, one of Rural New Yorker, two of 

 Russet Rural, and one of Green Mountain. The most serious injury 

 occurred in the early-maturing; varieties. In experiment No. 6 six 

 tubers of each variety were held 96 hours, with injury occurring to 

 two specimens of Triumph, two of Irish Cobbler, two of American 

 Giant, and one of Russet Rural. The Spaulding No. 4, Rural New 

 Yorker, and Green Mountain varieties suffered no injury. The aggre- 

 gate injury in this experiment was 17 per cent, while in experiment 

 No. 5 the injury totaled 31 per cent. 



Table II. — Freezing injury to seven varieties of potatoes held at 28° F. for 

 different lengths of time. 





Number of experiment and duration of exposure. 



Variety. 



No. 1, 7 

 hours. 



No. 2, 24 

 hours. 



No. 3, 48 

 hours. 



No. 4, 4$ 

 hours. 



No. 5, 70 

 hours. 



No. 6, 96 

 hours. 





Num- 

 ber of 

 speci- 

 mens. 



Num- 

 ber 

 in- 

 jured. 



Num- 

 ber of 

 speci- 

 mens. 



Num- 

 ber 

 in- 

 jured. 



Num- 

 ber of 

 speci- 

 mens. 



Num- 

 ber 

 in- 

 jured. 



Quan- 

 tity of 

 speci- 

 mens. 



Num- 

 ber 

 in- 

 jured. 



Num- 

 ber of 

 speci- 

 mens. 



Num- 

 ber 

 in- 

 jured. 



Num- 

 ber of 

 speci- 

 mens. 



Num- 

 ber 

 in- 

 jured. 





2 

 2 

 2 

 2 

 2 

 2 

 2 







20 





 2 

 

 1 

 

 

 



2 

 2 



2 

 2 

 2 

 2 

 2 





 

 

 (! 

 1 

 

 



Bush. 

 i 







11 

 11 

 11 

 11 

 11 

 11 

 11 



5 



6 

 5 

 4 

 1 

 2 

 1 



6 

 6 

 6 

 6 

 6 

 6 

 6 



2 



Irish Cobbler 



20 



2 



Spaulding No. 4 



American Giant 



Rural New Yorker. 

 Russet Rural 





 

 1 

 

 



20 

 20 

 20 

 20 

 20 



i 





 

 

 





 2 

 

 1 



a 





1 





Total 



14 



1 



140 



3 | 14 



1 



2 j 



77 



24 



42 



7 



In no case at 28° F. were the potatoes frozen solid. A superficial 

 examination would not have revealed any evidence of freezing injury 

 in any of these varieties. It is true that during subsequent storage, 

 however, these internally injured specimens are the first to break 

 down, although these potatoes do not show injury so far as their 

 external appearance is concerned and would be as salable in the 

 ordinary market as the uninjured ones. After a few days at ordinary 

 room temperature they are quite unfit for food. While no serious 

 injury occurred till the potatoes were held at least 70 hours, isolated 

 cases of freezing injury did occur even when potatoes were held only 

 7 hours. It is difficult to explain these isolated cases. For some 

 unknown reason certain individuals seem to bear much less under- 

 cooling than others of the same variety. Similarly, certain varieties 

 bear less undercooling than other varieties. There is a certain va- 

 rietal difference shown here. The Irish Cobblers seem to be the 

 first to succumb to freezing injury, followed by the Triumph, Ameri- 

 can Giant, Spaulding No. 4, and Russet Rural varieties. The Rural 

 New Yorker and Green Mountain varieties are the most resistant. 



