84 IMPROVING THE QUALITY OF WHEAT. 



A BASIS FOR SELECTION TO INCREASE THE aUANTITY OF 

 PROTEIDS IN THE ENDOSPERM OF THE KERNEL, 



White bread flour, which constitutes the major portion of the 

 wheat flour consumed in this country, is derived entirely from the 

 endosperm of the Avheat kernel. The portions of the kernel not 

 entering into the flour are the germ and the seed coat, attached to 

 each of which discarded constituents are portions of the endosperm. 

 The larger part of the aleurone layer either adheres to the hull and 

 constitutes the "bran" of commerce, or appears in the product 

 known as "shorts," and sometimes in low-grade flour. 



As it is the flour in which it is desired to increase the nitrogen, 

 and as the flour consists entirely of the endosperm, it becomes desir- 

 able to have some way to determine the nitrogen content of the 

 endosperm alone and to select for reproduction plants possessing a 

 large amount of nitrogen in this portion of the kernel. 



It is a question how this can best be done. A determination of 

 gluten by the ordinary method of washing, to carry off the starch 

 and fiber while the gluten is being worked in the hand, is not well 

 adapted for use with the small cpiantities of wheat obtainable from 

 a single plant. This also has the disadvantage that it gives no 

 indication as to the quality of the gluten. 



Determinations of gliadin and glutenin promise to be of some help 

 in affording a basis for selection from individual plants. It has 

 been shown by Osborne and Yoorhees " that the gluten of wheat is 

 composed of gliadin and glutenin. It does not necessarily follow, 

 however, that the sum of these two substances is a measure of the 

 gluten content of the sample analyzed. Osborne and Campbell'^ 

 have stated that the embryo of the wheat kernel does not contain 

 either gliadin or glutenin. This being the case, the sum of the 

 gliadin and glutenin would represent these proteids in the endosperm,j 

 with, perhaps, a small amount in tlie hull. 



A recent investigation byNasmith' leads him to conclude that 

 ghadin exists in afl portions of the endosperm, including the aleu- 

 rone layer, but that glutenin is contained only in the starch-bearing^, 

 portion of the endosperm. A determination of glutenin may, there- 

 fore, give an indication of the gluten content of the wheat. 



Table 19 shows the percentage of proteid nitrogen, the sum of 

 the gliadin and glutenin nitrogen, the amounts in grams of proteic 

 and of gliadin-plus-glutenin nitrogen in the average kernel, and thej 

 grams of proteid and of gliadin-plus-glutenin nitrogen in all of the 

 kernels on each plant. The plants are grouped into those having 



"American Chein. Jour., 1893, pp. 392-471. 



'Connecticut Experiment Station Report, 1899, p. 305. 



<Trans. Canad. Inst., 7 (1S03), Univ. Toronto Studies, Physiol. Ser. (1903), No. 4. 



