Potato Breeding 83 



East found that purples when selfed gave in some cases only 

 purples; in other cases, purples and whites; and in still others, 

 purples, reds and whites. Reds when selfed gave either reds alone, 

 or reds and whites. Whites gave only whites. No mosaics of red 

 and purple were obtained. The conclusion was that red is epi- 

 static to white, and purple, to both red and white. 



Salaman ^ selfed a red-tiibered plant of the variety Flourball and 

 got a ratio of 9 reds : 7 whites, suggestive of the action of two pairs 

 of factors. He believes that chromogen, a color base, is present in 

 all tubers. In the red tubers he assumed the action of an R factor 

 for color and a D factor which develops R. The second generation 

 would then give : — 



9 RD — red 



3Rd] 



3rD [ — white 



Ird J 



The red-tubered plant which Salaman self-fertilized was assumed 

 to be of the constitution Rr Dd. 



The Congo X Flourball (heterozygous for red) gave in Fi 13 

 black : 12 red : 4 white. 



Salaman holds that a factor for purple — P — is necessary in addi- 

 tion to the R and D factors to give purple. He has on four different 

 occasions united strains bearing white-skinned tubers to get colored 

 types. This may be a case of factor interaction similar to Bateson's 

 case of complementary colors in the sweet pea. 



Solarium etuherosum seems to have an inhibitor to the formation 

 of purple in the tubers. 



Flesh color. — Very little work has been done on this character. 

 Salaman notes that the color of flesh is inherited independently of 

 skin color. He says that colored flesh is apparently due to the 

 action of one pair of factors. 



Shape of tuber. — Both East and Salaman found roundness recessive 

 to other shapes. Round jiotatoes bred true in all cases. Salaman 

 found that long tubers bred true for long axis, but often varied in 

 diameter and hence in shape. Many oval-shaped potatoes were 

 found to be heterozygous and to break up when selfed into round, 



' Salaman, R. N. The Inheritance of Color and other Characters in 

 the Potato. Journ. Gen., Vol. 1, 1910-11. 



