JOHAL OF AGRiaJLTIML ffiSEMCH 



DEPARTMENT OF AGRICULTURE 



Vol. V Washington, D. C, December 27, 1915 No. 13 



CARBOHYDRATE TRANSFORMATIONS IN SWEET 

 POTATOES 



By Heinrich Hasselbring and LoN A. Hawkins, Plant Physiologists, Drug-Plant, 

 Poisonous-Plafii, Physiological, and Fermentation Investigations, Bureau of Plant 

 Industry 



INTRODUCTION 



In a former paper ^ embodying a study of the general course of the 

 carbohydrate transformations in sweet potatoes {Ipomoea batatas) 

 during storage, certain data were presented indicating that the sugar 

 content of sweet potatoes remains comparatively low while they 

 are in the ground, but that immediately after the roots are harvested 

 there is a transformation of starch into sugar which takes place more 

 rapidly at that time than at subsequent periods. It was pointed out 

 that this initial transformation seemed to be not greatly affected by 

 temperature, but seemed rather to depend upon internal factors. It 

 was suggested that possibly this initial change was associated with the 

 cessation of the activity of the leaves. In view of the fact that this 

 initial change appeared to be a phase of the carbohydrate metabolism 

 of the sweet potato which was inaugurated only under certain conditions 

 and which differed in some respects from subsequent changes, it seemed 

 worth while to investigate this process more fully in order to make out 

 something, if possible, as to its nature by a study of its progress at dif- 

 ferent temperatures. 



EXPERIMENTATION IN CARBOHYDRATE TRANSFORMATION 

 PLAN OF EXPERIMENTS 



The plan carried out in this work v^s, in general, to compare the 

 carbohydrate transfonnations taking place in sweet potatoes during a 

 period of 10 or 12 days immediately after they had been dug with the 

 changes taking place during a second subsequent period of equal length. 

 These experiments were carried out at temperatures of 30°, 15.5°, and 

 5°C. 



1 Hasselbring, Heinrich, and Hawkins, L. A. Physiological changes in sweet potatoes during storage, 

 /w Jour. Agr. Research, V. 3, no. 4, p. 331-342. 1915. Literature cited, p. 341-342. 



Journal of Agricultural Research, Vol. V, No. 13 



Dept. of Agriculture, Washington, D. C. Dec. 27, 1915 



bo G — 70. 



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