B. I'. 1.— .573. 



THF. SEPARATION OF SEED BARLEY BY THE 

 SPECIFIC GRAVITY METHOD. 



INTRODUCTION. 



The yield per acre of barley in the United States in 1909 was 24^?^ 

 bushels, which is 1| bushels less than the 10-year average from 1900 

 to 1909. A large i)art of the crop of 1909 was of poor equality and 

 li<;ht weight, weighing much less than 48 pounds per bushel, the 

 standard weight. 



The six-rowed barleys are principally grown in this country. The 

 head in this type of barley is made up of spikelets arranged in groups 

 of three upon the rachis. These contain one median and two lateral 

 grains. The median grain, having sufficient space to develop, is 

 usually large and plump, resembling that of the two-rowed type. The 

 lateral grains overlap each other, so that they are usually smaller, 

 twisted, and under unfavorable conditions inclined to be chaffy. 

 Experiments show that the plants produced from these lighter grains 

 are inferior to those grown from the larger median ones and fre- 

 quently do not produce as good grain. For this reason the seed for 

 planting should be thoroughly sorted and cleaned before seeding. 

 The method described here is recommended as a satisfactory means 

 of accomplishing this purpose. 



THE SPECIFIC GRAVITY METHOD OF SEED SEPARATION. 



The specific gravity method of seed separation consists in the im- 

 mersion of the seed in liquids of varying density. These different 

 densities are obtained by the addition of various quantities of salts or 

 other agents by which the specific gravity of the liquid is increased 

 or decreased, as desired. When different kinds of seeds are immersed 

 in these solutions, those which are lower in specific gravity than the 

 liquid in which they are ])laced will float on the surface. The 

 stren<'-th of tlie solutions must be varied for the different kinds of 

 seeds to be treated. In the separation of barley, however, water can 

 be successfully used. 



THE SPECIFIC GRAVITY METHOD AS APPLIED TO THE SEPARA- 

 TION OF SEED GRAIN. 



A simple plan for separating seed barley by the specific gravity 

 method has been successfully used by the Office of Grain Investigations 

 during the past year. The a})paratus used consists of two tubs or 



[Cir. OU] 3 



