Jan. 7, 1918 Behavior of Sweet Potatoes in the Ground 



II 



Table II. — Percentage composition of sweet potatoes in iQog, according to Keitt 



Date. 



Aug. 31 

 Sept. 10 

 Sept. 21 



Oct. 10 



Oct. 26 



Aug. 31 



Sept. 10 



Sept. 21 



Oct. 2 



Oct. 10 



Oct. 26 



Aug. 31 



Sept. 10 



Sept. 21 



Oct. 2 



Oct. 10 



Oct. 26 



Aug. 31 

 Sept. 10 

 Sept. 21 

 Oct. 10 

 Oct. 26 



Variety. 



Pumpkin yam. 



do 



do 



do 



....do 



Purple yam. 



do 



....do 



....do 



....do 



....do 



Polo. 



.do. 

 .do. 

 .do. 

 .do. 

 .do. 



Brazilian. 

 ....do... 

 ....do... 

 ....do... 

 ....do... 



Water. 



72.45 

 66. 12 

 74.27 

 68.34 

 70. 20 



66. 97 

 64.71 

 62. 42 

 61.59 



60. 91 

 63-83 



66.81 

 68.24 

 69.44 

 67.98 



61. 24 

 66.08 



67-45 

 64.31 



65-51 

 66. 22 

 69.97 



Starch . 



58. 22 

 57.20 

 55-03 

 53-03 

 59.60 



63-73 

 61. 06 

 69. 10 



69. 72 

 56.46 

 71. 00 



70.44 



61. 52 

 68.52 



64-55 

 58-38 



70. 70 



70.78 



62. 96 

 69.99 



55-21 

 65-77 



Glucose. 



13-03 



11.98 



6.18 



3-95 

 4-5° 



8.27 

 9. 18 

 3-70 

 6.77 

 2. 76 

 4. 06 



7.28 

 8.21 

 2. 61 



3-85 

 4.86 



Sucrose. 



2. 50 



5-73 

 8.94 



9-95 

 14.70 



2.32 



5-74 

 3-98 

 7. 16 

 7.70 

 8.26 



Total 

 carbohy- 

 drates. 



73-75 

 74.91 



70.15 

 66. 93 

 78.80 



77-51 

 73-75 

 77-56 

 81.67 

 66. 77 

 81.56 



79-63 

 77-39 

 78.77 

 71.79 



67-43 

 81.64 



83.80 



75-15 

 79.76 

 66.76 

 78. 89 



These figures exhibit considerable fluctuation. In 1908 there was as 

 a rule a decrease in the percentage of starch from August 28 to September 

 18, then a sudden increase from September 18 to September 29, and an 

 equally sudden fall from September 29 to November 18. A frost which 

 killed the vines occurred on November 6. The Polo variety does not con- 

 form to the others in its behavior. During the same period all the 

 varieties show a decrease in sucrose up to September 29, and an increase 

 from that time until November 18. The glucose shows a gradual increase, 

 reaching a maximum in the different varieties between September 18 

 and September 29, after which there is a loss of glucose. During the 

 next year the figures show even greater irregularity. The percentage of 

 starch fell and rose alternately between each pair of successive dates. 

 It is notable that after the frost which killed the vines on October 13, 

 the starch content of all varieties increased considerately. Hence, there 

 is one year a loss of starch after the death of the vines and in the following 

 year an increase. The figures representing the percentages of glucose 

 and sucrose fluctuate irregularly, but in general it may be said that the 

 glucose fell throughout the season, while the sucrose increased. It is to 

 be noted, however, that after the frost both sugars increased. Thus, we 

 have the remarkable phenomenon of an increase in the percentage of 

 of total carbohydrates in the roots after the vines had been killed. 



