ALFALFA ROOT STUDIES. 9 



VARIETIES STUDIED. 



Field studies of the root systems of the more common commercial 

 varieties or strains of alfalfa and of forms of the yellow-flowered 

 species {Medlcago faJcata) have been conducted at the Redfield field 

 station at various times between 1914 and 1920. The varieties and 

 strains ^ taken into consideration include the Peruvian, Poona/ 

 southern-grown common, northern-grown common, Turkestan, 

 Grimm, and yellow flowered, and form the basis of the principal part 

 of this study. 



The Turkestan, Grimm, and yellow-flowered alfalfas passed 

 through the four-season period from 1916 to 1919. incJusive. with 



Fig. 6. — Distortions and the production of branch roots in Grimm alfalfa plants 117 

 days old. These plants were confined in small flowerpots during the first 39 days. 



little thinning of stand. The southern-grown common had approxi- 

 mately 22.5 per cent mortality during the period, while the Peruvian 

 and Poona were almost completely winterkilled the first winter. The 

 tkroot systems of 12 consecutive plants of each variety and strain 

 'were taken in October, 1916, and photographed. In May, 1917, 

 after growing one season, 25, 75, or 100 plants of each variety and 

 iistrain were removed consecutively for the purpose of making obser- 

 iivations, measurements, and estimates of the more important root 

 licharacteristics. In August and October, 1919, after growing four 

 seasons, additional data were obtained by taking sets of the same 



I 



*For definitions and a classification of varieties and strains of alfalfa, see Farmers' 

 Bulletin 757. 

 2 An introduction from Poona, India. 

 103923°— 22 2 



