446 



Journal of Agricultural Research 



Vol. xxn, No. 8 



was imperfect. Fragments of the inner tissues of the glumes frequently 

 remained clinging to the carj'opsis and pieces of the outer layers of the 

 pericarp were as often removed with the glumes. It was thought that 

 this small interchange of tissue did not affect the results, but to be certain 

 a comparable series of kernels from a naked barley was studied. The 

 results were added to figure 4. The curv^e of the percentage of ash based 

 on wet weight is essentially the same as in the hulled varieties. In this 

 figure it is apparent that neither the application of irrigation water nor 

 the difference in the character of the barley influenced the percentage of 

 ash when computed on the basis of wet weight. The analyses of a num- 

 ber of mature samples of commercial naked varieties were also available. 

 When the ash was recalculated on a wet basis of 45 per cent water the 

 ash content was about the same as that obtained in the field. 



/.6 



.e 

 ,7 



I Z 3 9-^6 



7 8 9 10 II 12 J3 /^ iS 16 17 18- 19 20 Zl Z2232^2S 



Fig. 4.— Graph showing percentage of ash on the basis of wet weight in the kernels of Hannchen barley on 

 2 plots differently irrigated, in 1917, and of Baku barley grown in another year at Aberdeen; Idaho. 



DISCUSvSION OF RESULTS 



The extremely heavy deposit of ash in the awns of barley indicates that 

 the awn, or parts of the awn, are used as a depository for the excess ash 

 absorbed by the roots. The fact that some varieties contain much more 

 ash in the awns and rachises than others is due probably to two causes. 

 There most probably is a difference between varieties in the amount of 

 water transpired. As was shown in the irrigation plots at Aberdeen, 

 this results in a marked variation of ash deposit. There may also be a 

 difference in the selective functions of the roots of different varieties. 

 Some varieties may absorb more ash from the soil than do others. This 

 is strongly indicated in the ash content of the rachises. It is also of 

 greatest importance in this connection. Varieties of the Coast type are 

 characterized by a low ash content of the rachis. In most of the shatter- 

 ing varieties the rachises are high in ash content. The hooded varieties 

 have long been known to shatter badly. From results previously re- 

 ported it would seem that much of this is due to the loss of the awn as an 

 organ partially utilized for the elimination of ash. On the other hand. 



