Aug. 2, 1920 Development of Barley Kernels in Clipped Spikes 471 



barleys is indicated in the field experiments. These barieys have proved 

 relatively better in dry years on the northern plains than in wet years. 

 In the "good" years the hooded varieties have been far inferior to the 

 best bearded sorts, but in "bad" years they often have been better. 



In any case, these two experiments show that the awn has a function, 

 and the loss of the awn has resulted in a reduced yield. 



The second field problem is that of shattering. The common hooded 

 and awnless varieties have a tendency to shatter at maturity. The 

 clipped spikes of Manchuria and Hannchen barleys showed a ten- 

 dency in this direction; the normal spikes did not. The spikes from 

 which the awns were removed proved to be fragile, and many of them 

 fell to pieces as maturity approached. 



An explanation of this behavior was found in the determination of 

 ash in the awns, rachises, and paleae. The ash that normally went into 

 the awn was deposited largely in the rachis of the clipped spikes. The 

 additional ash seems to have been sufficient to cause the rachis to be 

 brittle. It would seem that the awn also served as a place in which to 

 store the excess of ash. More mineral matter probably is taken up in 

 growth than is needed by the plant. There is no method of elimination. 

 The extra mineral is deposited in cells which probably serve little purpose 

 other than storage. The removal of tissues and organs containing cells 

 which can be devoted to this end must, in itself, cause some derange- 

 ment of the normal processes of development. 



From the experiments conducted, it would seem that awnless and 

 hooded barleys are limited by the loss of the awns. It appears that high 

 yields are not to be expected from such varieties. It is to be expected 

 that such sorts will shatter more than awned kinds. This has been the 

 experience in breeding also. For the most part awnless hybrids have 

 been brittle and of low yielding capacity. It is thought that there is 

 little use in attempting to secure valuable awnless or hooded varieties by 

 means of hybrids with most varieties. One possible method of breeding 

 has been indicated by experiments not yet published. Some varieties 

 of awned barley have normally a much lower content of ash in the rachis 

 than others. It is possible that the progeny of crosses with these and 

 the hooded sorts may yield well in semiarid climates and that they will not 

 shatter. One or two such hybrids are now giving promise. 



When the first elementary experiment conducted in Minnesota indi- 

 cated the physiological difficulties in the way of producing desirable 

 varieties of hooded and awnless barleys, work was amplified in another 

 line. Several hundred hybrids with smooth awns have been produced 

 and tested. Much of this work has been done in the cooperative 

 experiments with the Minnesota Agricultural Experiment Station, but 

 many strains have been tried elsewhere. Several of these give promise 

 of good yielding capacity. 



