VARIABILITY IN THE RADISH' 



Excessive Variation of Root Crops Handicaps Commercial Grower — Careful 



Selection Should Secure Constancy — Seed of Ideal 



Types Should be Selected 



E. Eugene Barker and R. H. Cohen 



Nezu York State College of Agriculture, Cornell University, Ithaca, N. Y. 



ALL the root crops used as vege- 

 /\ tables show great variability in 



1 V most of their characters, espe- 



cially in size and shape. This 

 is true even in those kinds and varie- 

 ties which are supposed to be most true 

 to type. The best seed obtainable from 

 the most reputable firms is subject to 

 this same fault. 



This study was undertaken with the 

 purpose of obtaining some accurate 

 data as to the exact amount of varia- 

 bility in a representative kind of root 

 vegetable. It was also desired to as- 

 certain what genetic factors most affect 

 the yield. Three standard commercial 

 varieties were obtained from a seed- 

 house of good reputation. Two of 

 them, Scarlet Globe and White Box, 

 were supposed to reach marketable size 

 in four weeks from the date of planting, 

 while the third variety, White Icicle, 

 was a six-weeks variety. Four hun- 

 dred seeds of each variety were planted 



2 inches apart in rows in apparently 

 uniform soil in the garden. They were 

 planted about the middle of July and 

 were harvested and the data taken after 

 growing four and six weeks, respec- 

 tively. Owing to very hot and humid 

 weather that prevailed during this 

 time, they were all much overgrown 

 for market size. Their coarse, pithy 

 quality was due to the same causes. 

 This was especially marked in the 

 White Icicle variety whose final two 

 weeks of growth were excessively hot. 



THREE varieties DIFFER GREATLY 



The three varieties differed greatly 

 in regard to germination. (Fig. 10.) 



From 400 seeds of each variety, Scarlet 

 Globe germinated 246 seeds or 61.5%, 

 from which were obtained only 176 

 roots that could be considered market- 

 able ; White Box germinated 240 seeds 

 or 60%, from which were obtained 236 

 roots of marketable size; and White 

 Icicle 320 seeds or 80%, from which 

 were obtained 276 well-formed roots 

 of the typical White Icicle shape. The 

 remainder, which were discarded, were 

 not true to type. 33 of these being 

 "rogues," apparently of a different type, 

 and 11 failed to produce any good 

 root at all. 



An interesting condition came to light 

 in the White Box variety, indicating 

 that careless selection had been prac- 

 ticed in saving the seed. A few dozen 

 plants were about to bloom or had al- 

 ready come into flower when the roots 

 were dug. The roots of these preco- 

 cious plants were all long and thin and 

 not at all suitable for eating. About 

 one-fourth of all seeds of this variety 

 planted produced such roots. These 

 were discarded which accounts for the 

 peculiar distribution for weight in the 

 White Box variety, which is seen to 

 be entirely on one side of the mode. 



IDEAL SHAPES CHOSEN 



The measurements taken on each, 

 variety were weight in grams and 

 length (exclusive of the tap-root) and 

 greatest thickness in millimeters. The 

 Scarlet Globe and White Box varieties 

 are ideally globular in shape, while the 

 White Icicle is ideally long cylindric. 

 In order to have a standard constant 



1 This study was carried out by the junior author during the summer of 1917 in the Plant 

 Breeding Garden at the New York State College of Agriculture, Cornell University, All data 

 were taken and statistical computations reckoned by him. 



Paper No. 71, Department of Plant Breeding, Cornell University, Ithaca, N. Y. 



357 



