ALFALFA EOOT STUDIES. 



15 



roots, fibrous roots, and rooting rhizomes. The crowns are somewhat 

 larger than in the less hardy varieties, such as Poona and Peruvian, 

 but smaller than in Grimm and Turkestan. The taproot is prominent, 

 grows vertically downward, and tapers slowly. In diameter there is 

 no distinguishing difference between this variety, the Turkestan, 

 and the hybrid alfalfas, as is shown in Table 5. 



Fig. 10. — Root systems of Peruvian alfalfa plants, the growth of one season. 



As a result of the greater mortality in southern-grown common 

 alfalfa, each plant had more space than the ordinary varieties. It 

 is probable that with the same amount of space the differences in 

 root diameter would be somewhat greater than is shown in the table. 



Table 5. — Average diameter of taproota of different kinds of alfalfa at Redfield, 

 S. Dak., in 1917, 1919, and 1920. 



[Studies in 1917 and 1919 made on 1916 seedings; in 1920, on 1915 seedings.] 





Num- 

 ber of 

 plants 



ob- 

 served, 

 each 

 date. 



Measurements made within' 1 inch of the crown. 



Kind. 



Average root space per 

 (inches). 



pfent 



Average diameter of taproots 

 (mm.). 





May, 

 1917. 



Aug- 

 ust, 

 1919. 



Octo- 

 ber, 

 1919. 



Sep- 

 tember, 

 1920. 



May, 

 1917. 



Aug- 

 ust, 

 1919. 



Octo- 

 ber, 

 1919. 



Sep- 

 tember, 

 1920. 



Southern-grown common 



Turkestan 



100 

 25 

 75 

 32 

 32 

 19 

 22 



1.08 

 1.36 

 1.49 



1.30 

 1.60 

 1.30 



1.74 

 1.04 

 1.56 



'""2.' 12" 

 1.56 

 6.31 



2.18 



5.52 

 6.60 



6.84 



9.72 

 11.16 

 9.94 



5.60 

 10.52 

 11.25 





Grimm 





Southern-grown common 



a 11. .56 



Grimm 













12.43 



Decumbent yellow flowered. 



1 











11.00 



Prostrate yellow flowered. . . . 



1 











8.50 

















o The large root diameters in southern-grown common plants in 1919 may be accounted for by the high 

 mortality occurring between 1916 and 1919, which probably left the larger and stronger ones. 



