48 



BULLETIN 428, U. S. DEPARTMENT OF AGRICULTURE. 



Table VII. — Alfalfa plants transplanted in 1909 to hills 24 l)V 36 inches at 

 Brookings, S. Dak., showing yields of seed, 1910 to 1913, inclusive. 



Species. 



S. P. I. 



No. 



No. of 

 plants. 



Yield of seed per plant (grams). 



1910 



1911 



1912 



1913 



Average. 



Medicago sativa - 



20711 



20571 

 20714 

 20716 

 20717 

 20718 

 20719 

 20720 

 20721 

 20722 

 20725 

 20726 

 24452 

 24454 

 24455 

 24456 

 28070 

 28071 



145 



248 

 418 

 263 

 261 

 243 

 234 



62 

 159 

 213 

 225 

 238 

 708 

 434 

 156 



59 

 177 

 122 



2.80 



2.92 

 2.72 

 3.46 

 1.44 

 .35 

 .37 



3.70 



4.61 

 3.90 

 6.80 



0.924 



1.506 

 1. 108 

 2.231 

 .421 

 .352 

 .074 

 .209 

 .477 

 .375 

 .613 

 .586 

 .405 

 .180 

 .213 

 .205 

 .100 

 .176 



1.333 



.709 

 .641 

 1.353 

 .038 

 .181 

 .085 

 .258 

 .157 

 .122 

 .044 

 .247 

 .210 

 .073 

 .115 

 .169 



2.188 



Medicago sativa X Medicago 



2.436 



Do 



2.092 



Do 



3.461 



Medicago falcata 



.633 



Do 



.084 

 .025 



.241 



Do :.... 



.138 



Do 



.233 



Do 



.205 

 .216 

 1.69 

 1.44 

 1.28 

 .19 

 .53 



.126 

 .082 



.241 



Do 



.198 



Do 



.782 



Do 



1.22 

 .135 



.873 



Do 



.507 



Do 



.147 



Do 



.366 



.306 



Do 



.187 



Do 



.142 

 .47 



.073 

 .29 



.105 



Do 



.147 



.270 







Average yield of seed: 



Medicago sativa 













2.188 



falcata 











2.663 













.347 













A summary of Table VII shows clearly the relatively low yield 

 of seed from Medicago falcata. Allowing amply for the variation 

 in its different forms, there is none that approaches the ordinary 

 forms of Medicago sativa in seed production. In view of the ex- 

 treme uncertainty of the seed crop in the case of common alfalfa, 

 there is reason to assume that the utilization of Medicago falcata 

 as a cultivated crop will be seriously handicapped by the precarious 

 nature of its seed production. 



In addition to scanty seed setting and the material loss from 

 shattering, an appreciable percentage of the seed is " hard " and of 

 doubtful value for sowing. « As previously indicated in this paper, 

 50 per cent of hard seed is commonly found in the various strains 

 of Medicago falcata.. While the germination of a portion of this 

 seed can be hastened by treatment, no thoroughly practicable method 

 has yet been developed either for scratching the seed coat or ren- 

 dering it more permeable to water by the use of chemicals. There 

 is also an appreciable percentage of shriveled and nonviable seed, 

 so that the proportion of readily germinable seed rarely exceeds 40 

 per cent. Preliminary tests indicate that the viability increases with 

 age to a limited degree, aging apparently reducing the percentage 

 of hard seed. 



The comparatively small size of the seed offsets to some extent for 

 agronomic purposes the effect of the high percentage of hard seed. 

 There are approximately 325,000 to 490,000 seeds of Medicago fal- 



