8 



on this subject published in the Yearbook of this Department for 

 1901, Wiley concluded from a further series of experiments that the 

 length of the growing period was the determining factor in influ- 

 encing the composition of wheat, a short period of growth and a cool 

 climate producing a high protein content^ and vice versa. 



As far back as 1857 Laws and Gilbert a concluded from their 

 experiments at Rothamsted that the length of the growing period 

 after heading influenced the plumpness and the nitrogen content of 

 the grain; that is, a long period gives a plump grain with a low per- 

 centage of nitrogen. 



In 1893 Schindler 6 attributed the low percentage of nitrogen in 

 wheat to the long growing period from the time of bloom to ripeness. 



Climatic conditions have thus been given the most credit for 

 influencing the composition of plants. Jensen c pointed out that 

 the size of the grain decreased as the climate became more "conti- 

 nental " in character, and with the decrease in size the percentage of 

 nitrogen increased. This is shown by the fact that wheats grown in 

 the northwestern part of the United States and in Manitoba, Russia, 

 and Hungary (all having a continental climate, that is, cold and dry 

 winters, rain in late spring and early summer, and high temperature 

 at harvest) contain a high percentage of nitrogen and are hard and 

 almost flinty in character; whereas insular or coast climates produce 

 wheats high in starch, low in gluten, but plump and soft. 



In an article on agricultural research, A. D. Hall d calls attention 

 to the fact that climate produces greater changes in composition than 

 do fertilizers, soil, date of seeding, etc. 



Eckenbrecher e grew six varieties of barley in twelve different 

 localities and found that the same variety showed a much larger 

 variation in nitrogen content and in weight per 1,000 grains when 

 grown in the twelve localities than the six varieties did when grown 

 in any one locality ; that is, that climatic conditions, or environment, 

 exerted a greater influence than did the seed or even the variety. 

 Yet Hall, in the article just quoted, makes the statement that variety 

 is the chief factor in affecting the composition of plants; that each 

 race or variety possesses characteristics which are modified only to a 

 relatively slight extent by soil, seed, or climate. 



Yon Seelhorst/ showed that the more space there was between 

 plants the higher was the percentage of nitrogen and of ash ingredi- 



oSome Points on the Composition of Wheat, London. 

 6 Der Weizen, Berlin. 

 cExper. Sta. Rec., 1900-1901, 12: 737. 

 d Science, 1905, 22: 461. 

 Wochenschr. Brau., 1907, 24: 491. 

 /J. Landw., 1899, 47: 379. 

 [Bull. 128] 



