Nov. 15, i94i Ash Content of Awn, Rachis, and Palea 



435 



increment is quite uniform. In figure i it will be seen that within the 

 variety the rate of deposit has a direct relationship with the amount of 

 moisture in the soil and probably with the amount of water transpired. 

 On plot 8, which was not irrigated after flowering, the plants were suffer- 

 ing from lack of water during most of the time the kernels were devel- 

 oping. This lack of water is reflected in the percentage of ash in the 

 awns. The awns on this plot never contained as high as i6 per cent of 

 ash. The uniformity of the deposit was in no wise affected. The daily 

 increment, however, was less than on plot i, which received ample irriga- 

 tion. The normal ash content of tlie awn of Hannchen barley when grown 

 in the western United States is over 30 per cent at maturity. As will be 

 seen, the awns on the spikes from plot i reached this percentage several 

 days before matturity. Plots 2 to 7 received the same treatment as plot 8 

 until the time of their final irrigation. Only one irrigation after flowering 

 was given to any plot except plot i . The irrigation occurred on the day 

 the first ash determination was reported. Following the application of 

 water there was an acceleration in the rate of deposit of ash in plots 2 to 

 6, inclusive. The barley on plot 7 was maturing when the water was 

 applied. The leaves had begun to wither and the awns were almost 

 color-free at the time of the irrigation. The rate of deposit was not 

 materially increased over the rate on plot 8. The maturation was, how- 

 ever, delayed, and the final ash content of the awns was decidedly greater 

 than in plot 8. 



