PHYSIOLOGICAL PROCESSES DURING FLOWERING 449 



The high protein content of wheat resulting from an impeded 

 water supply is usually decreased with the application of artificial 

 irrigation, which contributes to a better filling of the grain with 

 starch. But as with irrigation the plants nevertheless continue 

 to endure atmospheric drought, the grain of irrigated wheats 

 remains richer in proteins than that of wheat grown in humid 

 climates and thus retains its higher baking qualities. Besides, 

 it is possible to produce a higher protein content by means of 

 introducing nitrogen fertilizers with the irrigation water, espe- 

 pecially in the second half of the vegetative period or toward 

 the time of the filling of the grain. It is also possible to produce 

 a higher protein content by toeans of selection; for it has been 

 observed that, in some varieties, irrigation decreases the protein 

 content of grain less than in others. 



Climatic conditions produce an analogous effect upon the 

 protein content of barley. Here, likewise, a more arid conti- 

 nental climate contributes to an increase of the protein content, 

 while a more humid maritime climate contributes to its decrease. 

 Therefore, barleys from less arid regions are more suitable for 

 brewing, in which a low protein content is desired; while barleys 

 "from arid regions are better for feeding purposes. Likewise, the 

 climate of high altitudes, differing from the climate of valleys in 

 increased humidity and lower temperatures,, produces barley 

 more suitable for brewing. 



The comparison of the chemical composition of grain from 

 different regions and districts cannot give a sufficiently clear 

 picture of the dependence of its composition upon geographical 

 factors; for different varieties are sown in different regions, and 

 this alone may account for the variations in the chemical compo- 

 sition, even when the plants are grown in a similar environment. 

 To get an idea of the significance of geographic factors, the same 

 varieties must be grown in different regions. This has been done 

 in extensive geographical experiments carried out by the Institute 

 of Plant Industry in Russia under the direction of N. I. Vavilov. 

 Those experiments have shown that the same varieties sown in 

 different geographical positions change veiy abruptly the compo- 

 sition of their grain. 



Chmatic conditions affect greatly the chemical composition 

 likewise of oily seeds. The total fat content does not change 

 significantly in different geographical regions, but the chemical 



