CLIMATIC RELATIONS 275 



flowering time may cause " blighted " or sterile heads. 

 An abundance of rust in this period will shrivel the kernel. 

 At this time, smuts and wheat scab appear, and in high 

 latitudes and altitudes there is the danger of frosts. 



In 1905 the author first applied the expression " fruit- 

 ing period " to this interval in the life of cereal crops, 1 

 and called attention to the correlations existing between the 

 length of this period and certain other characteristics of 

 the crop, as yield and protein content. Also the ratio of 

 length of this period to that of the whole period of growth 

 was determined for many varieties, under the same con- 

 ditions, and called the fruiting ratio or coefficient. Late 

 varieties and late plantings of the same variety have 

 shorter fruiting periods than others. The protein con- 

 tent increases inversely with the length of the fruiting 

 period. Blanchard first noted in print (1910, pp. 29-30) 

 the practical significance of a shortening of this period, 

 in reporting results of experiments with Chul and Fretes 

 wheats in California. The later these wheats were 

 planted, the shorter were both the growing and fruiting 

 periods, and the greater the content of protein. The 

 yields, however, decreased slightly as the protein content 

 increased. Thatcher (1913, pp. 39-47) and his students 

 studied this subject extensively, and arrived at the fol- 

 lowing conclusions: (1) the average weight of kernel 

 varies directly, and the percentage of nitrogen inversely, 

 as the length of the fruiting period. (2) The length of 

 this period is the determining factor in the final composi- 

 tion of grain. Schindler (1893), Lyon (1905), and others 

 also came to similar conclusions. 



1 In a paper, still unpublished, presented before the Agronomic 

 Seminar of the United States Department of Agriculture during 

 the winter of 1905-06. 



