UNITED STATES DEPARTMENT OF AGRICULTURE 
DEPARTMENT BULLETIN No. 1195 
Washington, D. C. T Maicb, 1924 
STERILITIES OF WILD AND CULTIVATED POTATOES WITH REFERENCE TO 
BREEDING FROM SEED. 
By A. B. Stout, Director of Laboratories, Ne w York Botanical Garden, and C. F. Clark , 
Horticulturist, Office of Horticultural Investigations, Bureau of Plant Industry. 
CONTENTS. 
Page. Page. 
Introduction 1 General survey, etc.— Continued. 
General survey of the tvues of sterility in the Sterility in hybrids 22 
potato 2 Sterility from incompatibility 23 
Sterilitv due to nonfloverins 2 Results of the sterility survey 26 
Sterility from one-sided impotence, or Summary 31 
intersexualism 4 Literature cited 31 
INTRODUCTION. 
The importance of the reproduction of the potato from seed balls 
is shown by the fact that nearly all of the most valuable varieties 
now in cultivation have been thus obtained. A few, however, are 
claimed to have originated as bud sports, but these have played a 
relatively unimportant part in potato production. Through seed 
propagation there have been developed numerous varieties, differ- 
ing in habit of growth, in time of maturity., in size, shape, and 
quality of tubers, and in adaptability to conditions in different 
localities. While there is still chance for further improvement 
regarding these characteristics, the most immediate demand for 
seed reproduction is in the need for varieties resistant to disease. 
The rapid spread of diseases of the potato during recent years, par- 
ticularly the extremely infectious diseases of the mosaic and leaf- 
roll types that are transmitted by aphids, makes breeding for resist- 
ance to disease highly desirable, if not necessary. 
The greatest difficulty -encountered in the breeding of the potato 
from seed is the marked sterility or lack of fruitfulness very generally 
present. This has been experienced by all who have sought to 
breed this plant. Many observations have been made with reference 
to the various aspects of fruitlessness, and numerous views have been 
expressed regarding the causes and conditions involved. No clear 
outline of this situation with reference to the distinctions between 
the several types of sterility now known to be present in other 
60229— 24-Bull. 1195 1 
