12 BULLETIN 1063, U. S. DEPARTMENT OF AGRICULTURE. 



The loss due to decay in this experiment was very small, the 

 average being only 1.10 per cent for all varieties. Among the 

 varities tested, those showing the greatest loss were the Gold Skin, 

 8.66; Big-Stem Jersey, 3.65; Pumpkin "Yam," 2.64; Haiti, 

 2.45 ; and Red Brazil, 2.18 per cent. Of the 27 varieties in the ex- 

 periment 4 showed no decay ; 7 varieties had a loss between 0.02 and 

 0.25 per cent; 6 varieties between 0.25 and 0.50 per cent; 1 variety 

 0.72 per cent; 4 varieties between 1 and 2 per cent, and the others 

 showed losses between 2.18 and 8.66 per cent. 



The conditions in the storage room were nearly ideal; therefore 

 the loss due to decay was so slight that differences between varieties 

 mean very little. 



Several varieties, chiefly those belonging to the Jersey group, 

 namely, Red Jersey, Big-Stem Jersey, Yellow Jersey, and Gold 

 Skin, though not showing excessive decay, had begun to deteriorate 

 and from a commercial point of view should have been removed 

 sooner. 



COMPARISON OF THE KEEPING QUALITIES OF SWEET POTATOES 

 WHEN STORED AT DIFFERENT TEMPERATURES. 



To determine the effects of different temperatures on the keeping 

 qualities of sweet potatoes, experiments were conducted during 

 1917-18 and 1918-19. Three standard varieties of sweet potatoes 

 were stored in each of three different rooms, where after the cur- 

 ing period it was the plan to maintain the temperature between 50° 

 and 55° F., 55° and 60° F., and 60° and 65° F., respectively. The aim 

 during curing was to keep the temperature high enough to cure the 

 potatoes properly, all three rooms being treated alike. After the 

 curing period the temperature was gradually lowered in each room 

 and an effort made to maintain it between the points mentioned. The 

 average weekly temperature usually varied only a few degrees, as 

 shown in figure 1. 



The shrinkage of sweet potatoes at the end of the curing period 

 and at various intervals during storage and the percentage of loss 

 due to decay are shown in Table 6. 



Table 6 shows that under all temperatures about half the shrink- 

 age occurred during the curing period. After the curing period the 

 shrinkage continues, but the rate is rather slow, averaging less than 

 1| per cent a month under the three sets of temperatures. Comparing 

 the average percentage of shrinkage under the three different tem- 

 peratures, it is seen that it is greater at the higher temperatures. The 

 difference between the first two sets is especially noticeable, and is 

 just as noticeable with the Big-Stem Jersey and Nancy Hall varieties 

 in the third set. The Southern Queen showed less shrinkage at 60° to 

 65° F. than at any other temperature. The average total shrinkage of 



