4^2 Journal of Agricultural Research voi. xix,no.9 



The awns of these hybrids are smooth. All the large scabrous teeth 

 on the basal two-thirds of the awn have been eliminated. The tips of the 

 awns are slightly rough, but this roughness is not sufficient to be objec- 

 tionable to either growers or feeders of barley. Whether varieties of this 

 type can be made to yield equally as well as the awned sorts remains to be 

 determined. 



SUMMARY 



The removal of the awns from a barley spike has a marked effect on the 

 development of the kernels of the spike. 



Kernels from clipped spikes have smaller volume and a lower weight of 

 dry matter at maturity than do those from normal spikes. 



The difference is not due to the injury or shock of removing the awns; 

 the kernels in the clipped spikes develop as rapidly as those in the normal 

 spikes for several days after the awns are clipped. 



About one week after flowering the deposit of dry matter in the ker- 

 nels of the normal spikes begins to exceed that in the kernels of the 

 clipped spikes. This is about the time that rapid starch infiltration 

 begins. 



The daily deposit of nitrogen and ash is more nearly equal in the two 

 classes of spikes than is the deposit of starch. 



In normal spikes at Aberdeen, Idaho, the awns contained more than 

 30 per cent of ash at maturity. When the awns were removed a part of 

 this ash apparently was deposited in the rachis. The rachises of the 

 clipped spikes contained about 25 per cent more ash than the rachises 

 of the normal spikes. 



The additional ash in the rachises of the clipped spikes probably was 

 responsible for the tendency of these spikes to break. The indications 

 are that the elimination of the awns results not only in lower yields but in 

 shattering as well. 



Hooded and awnless barleys generally yield less and shatter more 

 than awned varieties, and there seem to be physiological reasons for this 

 fact. 



It may be possible to produce nonshattering hooded and awnless sorts 

 by using parents which normally have a low percentage of ash in the 

 rachises. It may be possible to obtain strains that will give good yields 

 under arid conditions. Under humid conditions it is likely that the 

 objections to the awns are more easily met by the use of strains with 

 smooth awns, which, so far as known at present, have no physiological 

 limitations. 



