1913] Shaw: Studies on Influences Affecting Protein Content of Wheat 65 



In practieall}^ all of the former studies of this subject the 

 plan has been to transfer the seed from one point to another and 

 thus change the environmental conditions, and from the results 

 so secured to attempt to draw general conclusions. Under such 

 conditions, changes, not merely in environment, but also in soil, 

 were accomplished, thus introducing too many variables. In 

 the experiments here recorded two general methods have been 

 followed: (a) the production of numerous varieties of wheat in 

 the field on a small area of uniform soil and varying other con- 

 dition of growth than the soil, and (h) growing wheat from the 

 same seed under the same conditions on soils of widely different 

 origin placed under the same cultural and climatic influences. 

 The large and important question involved is the cause or causes 

 of the relatively low gluten content of wheat grown under Cali- 

 fornia conditions. In this connection, it is particularly desirable 

 to know whether or not such tendency to change as exists is 

 constant; whether it is due to some climatic influence, the time 

 of cutting, the time of seeding, the bleaching action of the sun, 

 the effect of early and late application of moisture, the efi^ect 

 of cold nights, of varying amounts of sunshine during the rip- 

 ening period, or to some induced or inherent condition of the 

 soil. The work which we have conducted has aimed at the solu- 

 tion of all of the questions just mentioned and consisted of 

 several parts each of which dealt with one of the questions 

 involved. 



Variation in the Protein Content op Wheat 



Seasonal Variation. — It has been observed that from season 

 to season there is a marked variation in the protein content of 

 wheat even though grown upon the same soil, a seeming indi- 

 cation that the seasonal factor is considerably greater than the 

 soil factor in protein formation. This may be shown from a 

 number of samples grown during the course of the experiments, 

 some of which are given below. These wheats have b(!en grown 

 each year on the same soil and under the same cultural conditions 

 at the University Farm at Davis, California. 



