54 BULLETIN 698, U. S. DEPARTMENT OF AGRICULTURE. 
selves, either in: height, or earliness, or in producing power. A plat 
of Blackhull kafir is shown in figure 9. 
Table XIX shows that in fairly normal seasons, sion as those of 
1908, 1911, and 1915, this variety requires eiyow three months to 
reach the heading stage and nearly a month more to ripen, making 
the total duration of the growing period 115 to 120 days. The 
shortest period recorded is 107 days, for No. 207 in 1908, and the 
longest is 150 days, for three selections in 1915. Drought may 
shorten the vegetative period slightly by checking growth and so in- 
ducing heading. On the other hand, drought may greatly lengthen 
this period if it becomes so severe as to inhibit growth altogether 
Fie, 9,--A plat of Blackhull kafir, C. I, No. 203, at the Amarillo Cereal Field Station, September 10, 1907: 
until rains occur. This condition occurred in 1916, when the average 
duration of the vegetative period alone was 128 days and none of 
the five selections matured. 
The normal height of these varieties under Panhandle conditions 
is about 5 feet. Drought in early summer reduces this height mate- 
rially. For instance, in 1910 to 1912, inclusive, the average height 
was between 4 and 4.6 feet. In 1914 and 1916 the average height 
fell below 4 feet, while in 1913 the crop was destroyed by drought at 
an average height of only 2 feet, mostly without producing any heads. 
In 1915, when the total precipitation was much above normal and the 
highest yields yet recorded were obtained, the average height was 
only 5.1 feet. This was due, however, to a somewhat reduced rain- 
fall in May and June, while growth was being made, and super- 
abundant moisture thereafter while the grain was being formed. 
