42 BULLETIN 33, U. S. DEPARTMENT OF AGRICULTURE. 



grains. In the F 1 generation the plants are covered with a light 

 straw mulch to prevent winterkilling. In the F 2 generation the}' are 

 planted in the regular nursery row at the usual rate and tested for 

 winter resistance. The parent strains are planted as checks. This 

 work was retarded by the hailstorm in July, 1912, when practically 

 all of the crosses made in that year were destroyed. No conclusions 

 can be drawn from the work already done, although there are now in 

 existence several apparently hardy strains. 



In this connection it is of interest to note that Nilsson-Ehle 1 has 

 concluded that the winter-resistant character is transmitted as are 

 other characters, that crossing results in segregation of gradations 

 of this character, and that it seems to be the result of a variety of 

 combinations of many Mendelian factors. 



MISCELLANEOUS TESTS. 



Several cultural tests have been under way in the nursery with the 

 different varieties of cereals, but the results of these tests are not 

 germane to the purposes of this bulletin. 



SUMMARY. 



Cooperative experiments with cereals have been conducted at the 

 Dickinson (X. Dak.) substation since 1907. The testing and im- 

 provement of cereal varieties have constituted the major part of the 

 work. 



The substation is located near the center of Stark County, in south- 

 western Xorth Dakota, at an elevation of approximately 2,500 feet. 



The average annual rainfall at Dickinson for the 22 years from 

 1892 to 1913, inclusive, was 15.46 inches, of which 70.1 per cent fell 

 during the months from April to August, inclusive, the growing sea- 

 son at Dickinson. The average precipitation for the growing season 

 for the years 1907 to 1913, the period during which cooperative ex- 

 periments with cereals have been conducted, was 11.54 inches. The 

 average evaporation from a free water surface during the same period 

 was 29.524 inches. 



The average wind velocity per hour during the months from May 

 to August, inclusive, for the 6 years from 1908 to 1913 was 7 miles. 

 The average mean temperature for these months was 57° F. ; the av- 

 erage length of the frost-free period, 99 days. The maximum frost- 

 free period was in 1909, from May 17 to September 14, 120 days. 

 The latest date at which frost has occurred in the spring in the seven 

 years was June 5 ; the earliest frost in the fall was on August 19. 



1 Nilsson-Ehle, Herman. Zur Kenntnls der Erblichkeitsverhaltnisse der Eigenschaft 

 Winterfestigkeit belm Weizen. in Z'.sr.'ln-. Pflanzenzucht., Bd. 1, Heft 1, p. 3-12, 1912. 



