PLANT BREEDING 425 



(4) Plantmg the mother roots selected in (3) for the 

 production of what is called "ehte seed." 



(5) Growing from elite seed small beets which are planted 

 to secure commercial seed. 



It requires five years to obtain seed in large quantities from 

 the very few selected roots with which the process of securing 

 improved seed is begun. i 



Some notion of the thoroughness with which European 

 seed growers choose their beets may be gathered from the 

 fact that in 1889-1890 one of the most important firms tested 

 2,782,300 roots, from which it selected only 3043 to be planted 

 for seed production. Constant pains must be taken in main- 

 taining the best possible seed supply, as the quality becomes 

 lowered at once when the seed is grown without special pre- 

 cautions. This is due to the fact that the variations in beets 

 are not elementary species (Sect. 383), and therefore are not 

 sure to come true from the seed. Two of the most serious 

 ways in which a poor stock of sugar beets falls short are in 

 the low percentage of sugar and in the production of many 

 worthless annual plants. In central Europe the annual indi- 

 viduals sometimes constitute 20 per cent of the entire crop. 



The average yield of sugar from American-grown beets is 

 at present 12 per cent or less. Exceptional beets have been 

 found to contain more than double this amount. It is impos- 

 sible at present to produce the roots in large quantities with 

 anywhere near this high percentage of sugar, but decided gains 

 may easily be secured, and an increase of 2 per cent in the 

 yield would mean a gain of something like $100,000 per year 

 in the beet-sugar production of the United States. 



389. Constant and inconstant varieties. Beets, as stated in 

 Sect. 388, do not long remain true to type unless there is con- 

 tinued selection of the seed. There is a constant tendency of 

 the high-bred sugar beet to "run out," — that is, to revert to 

 the average sweetness of beets grown from unseleeted seed. 

 In this respect beets differ sharply from the cereals, most of 

 1 See Yearbook of the Department of Agriculture, 1904. 



