142 BOTANY OF CROP PLANTS 



occurrence of anthocyanin in the pericarp of hull-less barleys 

 is more significant than its production in the aleurone layer." 



Gennination of Barley. — Haberlandt gives the following 

 as the germinating temperatures of barley: optimum 68°F. , 

 minimum 37.4° to 39.2°F., maximum 82.4° to 86°F. In 

 brewing, much emphasis is placed upon the "germinating 

 energy" of the grain. By this is meant its ability to germi- 

 nate within a specified time. A high germinating energy is 

 96 per cent, in seventy-two hours when kept at 64.4° to 

 68°F. 



Much importance is attached to the secretion of enzymes 

 and the conversion of endosperm in the germinating of barley 

 grain. A barley of high diastatic power is preferred ; by this 

 is meant the ability to produce an abundance of the starch- 

 dissolving enzyme — diastase. Small grains, with a high 

 nitrogen content have a high power of forming the enzy- 

 matic secretions. The enzymes secreted during germination 

 are chiefly diastase, cytase, and proteases, and it is quite 

 probabJe that the epithelial layer of the scutellum is the 

 secreting organ. It has been pointed, out by Mann and 

 Harlan that "the greatest secreting area for a given grain 

 is secured with a scutellum extending well over the edges of 

 the adjacent endosperm; the greatest vigor in an epithelial 

 layer of long, narrow cells, the highest condition of efl[iciency 

 in a well-matured, well-cured grain." As has been indicated, 

 the principal enzyme secreted by the germinating embryo 

 is diastase. It has the specific property of changing starch 

 to sugar. Hence, the reserve starch in the embryo, converted 

 to soluble and diffusible sugar, serves to nourish the young 

 plant. Cytase is a cellulose-dissolving enzyme. Protease 

 renders the insoluble proteins soluble. 



The primary root is the first to appear. This is followed 

 by the secondary ones, and the young shoot. The shoot 



