Varieties of Roots. 



151 



higher dry matter content and yet retain the heavy yielding power. 

 Unfortunately, several of those who have thus crossed these plants have 

 not had a proper means of measuring the dry matter content, but have 

 selected for external characters only, with the result that many of the 

 varieties of half-sugar mangels are no richer in dry matter than common 

 mangels, and some are inferior. 



General observation supported by some experiments have shown that 

 beets that grow deep in the soil contain, on the average, a somewhat 

 higher percentage of dry matter than others. Thus, in the case of man- 

 gels the globe varieties with 80 per cent, of their root above ground will 

 contain on an average 7 to 10 per cent, dry matter. The tankard varieties 

 with 60 to 70 per cent, of the root above ground contain 8 to 11 per cent, 

 dry matter. The long varieties with 35 to 50 per cent, of the root above 

 ground contain 9 to 14 per cent, dry matter. Of sugar-beets, those 

 growing with all of the root below ground are, on the average, higher in 

 dry matter content than those with 30 to 40 per cent, of the root above 

 ground. This general 

 statement cannot, how- 

 ever, be used in regard 

 to individuals ; for it is 

 possible to .'•ecure a globe 

 or a tankard-shaped 

 mangel with 20 per cent, 

 of dry matter, so that in 

 selection of " mother 

 roots," shape cannot be 

 used as a basis for selec- 

 tion. Furthermore, it 

 has been observed that 

 heavy individuals within 

 a variety will run lower 

 in dry matter than those 

 of lighter weight. At the 

 same time it has not yet 

 been determined whether 

 a large crop of heavy 

 mangels will yield more 

 dry matter than a smaller crop of light mangels. We do not yet know 

 what is the ideal weight of an individual. 



Points to consider in selecting a " mother " mangel: 



I. The yield of dry matter. This involves consideration of two 

 factors : 



FiG.^61. — Hollow Crown parsnip. In one test this 

 variety yielded eight tons fresh substance, one 

 and six-tenth tons dry matter per acre. Seed must 

 be fresh. Grows slowly while small. 



