110 University of California Publications in Agricultural Sciences [Vol. 1 



Comparing the weather reports at Davis for the months of 

 April, May. and June, we find that this period during 1909 was 

 much drier and somewhat warmer than the corresponding months 

 the year before. As this is the time when the greatest develop- 

 ment of the kernel takes f)lace. it is not at all unlikely that these 

 climatic differences may account to some extent for the dif- 

 ferences in composition of the grain. The moister and cooler 

 condition of 1908 may have prolonged the developing and rip- 

 ening period, thus favoring the storing of a larger amount of 

 starch. Other seasonal differences not recorded have doubtless 

 also contributed their share. 



The difference in protein content for the two seasons at Tulare 

 is just as marked as at Davis, but the order is reversed. No 

 weather reports from the immediate vicinity were available, so 

 we can make no comparison with the Davis conditions. 



Another rather striking seasonal difference brought out by 

 the table is the percentage of gliadin to total protein. The years 

 that the percentage of total protein is high, the percentage of 

 gliadin to total gluten is also high. In fact, the difference in the 

 gliadin content of the wheat samples for the two years is pro- 

 portionally greater than the difference in total protein. This 

 would lead us to believe that the gliadin is affected more by the 

 season than the other protein compounds. "We find, however, 

 little or no relation between the gliadin content and the sunshine 

 received. 



In conclusion, then, it is safe to say that while sunshine does 

 exert some influence upon the composition of the wheat grain, 

 there are other climatic factors which also exert very marked 

 influences in this direction. AYe find that the protein does not 

 increase inversely as the sunshine, but that there is an optimum 

 condition under which the greatest development of protein takes 

 place. This optimum of sunshine is somewhat less than normal 

 in the valleys of this state. Other things being equal, too little 

 sunshine lowers the protein content to just as great an extent as 

 too much sunshine. This condition is probably due to the fact 

 that a certain amount of sunshine is necessary in order that the 

 normal physiological functions of the plant ma}' take place. 

 When the amount of sunshine is reduced to one quarter or one 



