UNITED STATES DEPARTMENT OF AGRICULTURE 



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BULLETIN No. 958 



Contribution from the Bureau of Plant Industry 

 WM. A. TAYLOR. Chief 



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Washington, D. C. 



August 22, 1921 



DEVELOPMENT OF TUBERS IN THE POTATO. 



By Charles F. Clark, Horticulturist, Office of Horticultural and Pomological 



Investigations. 



CONTENTS. 



Page. 



Scope of the experiments 1 



Work of previous investigators 1 



Description of the t uber-bearing parts 4 



Page. 



Details of the experiments 4 



Summary 25 



Literature cited 27 



SCOPE OF THE EXPERIMENTS. 



The conditions which attend the setting and subsequent develop- 

 ment of the tubers of the potato (Solanum tuberosum L.) are of 

 interest not only to the plant physiologist but also to the practical 

 grower, as a knowledge of the relation of these factors to crop pro- 

 duction may, to a certain extent, be put to practical use. 



The experiments described in the following pages were conducted 

 at the Colorado Potato Experiment Station, Greeley, Colo., duruig 

 the seasons of 1916, 1917, and 1918. A few minor observations were 

 also made in Maine in 1919 for the purpose of verifying the conclusions 

 previously reached relating to the time of the beginning of tuber 

 formation. 



While these studies could profitably be extended to cover a longer 

 period and include a greater number of varieties and a wider range 

 of environmental conditions, it is deemed advisable to place on 

 record the results obtained up to the present time, since these lines 

 of investigation have been temporarily suspended. 



WORK OF PREVIOUS INVESTIGATORS. 



While very extensive studies of the potato plant have been made, 

 the development of tubers has received comparatively little atten- 

 tion. Jones and Orton (5, p. 155-156)^ report results obtained 



1 The serial numbers in parentheses refer to " Literature cited" at the end of this bulletin. 

 47473°— 21— Bull. 95S 1 



