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BULLETIN 1074, U. S. DEPARTMENT OF AGRICULTURE. 



LENGTH OF THE KERNEL. 



The length of the kernel is used here as a major character in dis- 

 tinguishing varieties of common and club wheat. 



Koernicke and Werner (133), in their descriptions of wheat varie- 

 ties, indicated the average length and width of the kernels in milli- 

 meters and the average number of kernels in 10 grams. The kernels 

 were described as very small, small, large, and long. Heuze (112) 

 described the kernels as short, medium, or long. The size of the 

 kernels of any variety varies slightly when grown in different sec- 

 tions or in different years in the same section. From necessity, there- 

 fore, the limits of the classes in which varieties are placed must be 



overlapping. A kernel of wheat reaches its 

 maximum length several days before ripen- 

 ing. The length, therefore, is fairly con- 

 stant, even when it is considerably shrunken, 

 and is the most valuable of the kernel dimen- 

 sions for taxonomic purposes. In mak- 

 ing measurements only the normal kernels 

 should be used. The kernels from the tip 

 spikelets on a spike and from the upper 

 florets in the spikelet are below normal in 

 length. 



In the keys two classes are made, namely, 

 kernels short to midlong and kernels mid- 

 long to long. In the descriptions three 

 classes — short, midlong, and long — sometimes are mentioned sepa- 

 rately. These kernel lengths are shown in Figure 10. 



The short to midlong class includes varieties whose kernels meas- 

 ure within the limits of 4 to 7.5 mm. in length. The midlong to long 

 class includes varieties whose kernels come within the limits of 6.5 

 to 10 mm. For individual samples more definite limitation is pos- 

 sible. For this purpose the term " short " is used for kernels varying 

 from 4 to 6 mm. in length ; " midlong " for those varying from 6 to 8 

 mm., and "long" for those varying from 8 to 10 mm. These latter 

 measurements are considered as minor characters and are occasionally 

 used in descriptions either alone or usually following the adjective. 

 The measurements, enlarged ten times, are illustrated in Figure 11. 



Fig. 10. — Kernel lengths : a, 

 Short;* 6, midlong; c, long. 

 (Natural size and enlarged 3 

 diameters.) 



TEXTURE OF THE KERNEL. 



The texture of wheat kernels is an important character in classi- 

 fication. It has an economic value in America, as most wheat is mar- 

 keted in commercial classes, which are fixed largely on a basis of 

 texture, because hard wheats generally are better for milling and 

 bread making than soft wheats. 



