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BULLEri:S" 1087, U. S. DEPAETMEXT OF AGEICULTURE. 



SUMMARY. 



Factors tending to produce modifications of taproots in alfalfa 

 are soil, climate, cultural treatment, and injuries. 



Studies made at Kedfield, S. Dak., were on varieties seeded at the 

 same time and grown under the same soil and moisture conditions. 

 Even with the greatest care, however, it is difficult to make allow- 

 ances for differences in root growth of the various varieties, owing 

 to the nonuniform thinning of the stand by severe climatic condi- 

 tions or other causes. 



The varieties and strains studied include Peruvian, Poona, south- 

 ern-grown common, northern-grown common, Turkestan, Grimm, 

 and yellow flowered. The root systems of the Peruvian and Poona 

 alfalfas of one season's growth are quite similar. Thej'- are charac- 



FiG. IS. — Root systems of decumbent yellow-flowered alfalfa plants, the growth of six 



seasons. 



terized by small, upright crowns, distinct taproots, comparatively 

 few branch roots, and few fibrous roots, which are distributed rather 

 uniformly over the root system. They differ in that the Poona sel- 

 dom has branch roots on the upper portion of the taproot. 



For convenience, the common alfalfas are divided into two classes. 

 the southern-grown common and the northern-grown common. All 

 these alfalfas have distinct taproots and in general show consider- 

 able similarity. The northern-grown strains have somewhat broader 

 crowns and they exhibit more of a tendency to throw out branch 

 roots and fibrous roots, but these differences are not sufficiently 

 marked to constitute conspicuous characteristics. Both exceed the 

 Poona and Peruvian alfalfas in branch and fibrous root develop- 

 ment. There is practicalh^ no difference in the diameter of the tap- 

 root. 



M 



