BULLETIN OF THE 



No. 183 



Contribution from the Bureau of Plant Industry, Wm. A. Taylor, Chief. 

 April 13, 1915. 



(PROFESSIONAL PAPER.) 



MORPHOLOGY OF THE BARLEY GRAIN WITH REFERENCE 

 TO ITS ENZYM-SECRETING AREAS. 



By Albert ;Maxx, Plant Morphologist, Office of Agricultural Technology, and H. V. 

 Harlan, Agronomist in Charge of Barley Investigations, Office of Cereal Investiga- 

 tions. 



CONTENTS. 



Page. 



Introduction 1 



Structure of the barley grain 2 



Development of the barley grain 5 



Germination 8 



Conversion of the endosperm 9 



Resume of the conclusions of other investi- 

 gators 10 



Source of diastat ie ferments 12 



Location of dii^tase secretion 17 



Page. 



Source of cytatic and proteolytic ferments. . . 18 



Function of the aleurone layer 18 



Greater diastatic power of small-berried and 



of high-nitrogen barleys 19 



Efficiency of conversion 21 



American barleys 27 



Modifications possible by culture 28 



Foreign barleys 30 



Summary 31 



INTRODUCTION. 



Tho value of the barley crop to the American farmer depends upon 

 two factors, the yield per acre and the price per bushel. An increase 

 of revenue is as readily effected by one as by the other. The yield is 

 necessarily an agricultural problem; the price is also, within certain 

 limits. iUthough the daily price of any market product ordinarily 

 varies over a considerable range, higher values are placed upon those 

 offerings which most perfectly meet the requirements of consumers. 

 A superior cjuality is the equivalent of a gnniter quantity. The nearer 

 a fanner can comt? to produchig a prochict ideally suited to its uses, 

 the higher will be the prices which h(^ will be able to command. 



By far the greatest demand upon the barley cro]) is for tlie ])n]'p()se 

 of malting. This operation consists essentially in the breakijig down 

 of the cell waUs of th(! endosperm of the barley grain so as to leave its 

 Htandi grains exposed to later enzymatic actions, and also in (lie 

 abundant production of these enz-yms, jjoth tiie diastatic and ])rn- 

 teolytic. The abundant formation of diastase has long been con- 



NoTK, -This i»ar)cr U intended for distribution to agronomlHti, station dlroctors, brewery chomlsls, and 

 selected irialtst^rs. 



76719"— Bull. 1H.J— 1.0 1 



