Io6 BOTANY OF CROP PLANTS 



glutenin. The latter two proteins compose gluten. Gliadin 

 is the sticky substance in gluten. 



As a general rule, grains that have a marked glutenous or 

 horny or flinty appearance are higher in protein than those 

 that have a starchy or dull appearance. However, it is 

 known that a given variety may produce a grain that is hard 

 and rich in gluten; or one that is soft and low in gluten, de- 

 pending on the environmental factors. But it seems true, 

 nevertheless, that the term "quality" refers to both the 

 physical characteristics and chemical composition of the 

 grain. 



Relative Proportions of the Parts of the Grain. — 



1. Bran (pericarp, testa, nucellus), 8 to 9 per cent. 



2. Aleurone layer, 3 to 4 per cent. 



3. Starchy or floury endosperm, 82 to 86 per cent. 



4. Embryo or germ, about 6 per cent. 



"Hard" and "Soft" Wheats.— A "hard" wheat is one with 

 a horny or flinty texture, and quite high in protein. Hard 

 wheats, as a result of their high gluten content, make a 

 "strong" flour, which is adapted for making Ught bread. 

 A "soft" wheat is more easily crushed than a hard wheat, has 

 a starchy or dull appearance, and is relatively rich in starch. 

 The "soft" wheats have been regarded with favor for the 

 making of bread and pastry flours. However, the flour from 

 soft wheats is said to be "weak," that is incapable of making 

 a large heavy loaf. At first there was much opposition to 

 hard wheats, because of difliculties in milling and baking. 

 In recent years, however, this opposition has been largely 

 overcome. 



There are three classes of hard wheats in this country: 

 (i) hard spring wheat, (2) hard winter wheat, and (3) 

 durum wheat. The principal hard spring wheats are Fife 



