128 FIELD CROP PRODUCTION 



protein. This difference in the physical character of the 

 kernel is due, in part, to the fact that if favorable growing 

 weather prevails during the ripening period, the plant 

 continues its growth until the starch cells of the kernels 

 are completely filled, which gives to the kernel a light 

 color and a soft, starchy endosperm. If, however, hot, 

 dry weather prevails during the ripening period, the plant 

 ripens prematurely, and before all of the starch cells of the 

 kernel have been filled by the transfer of starch from the 

 leaves and stem to the kernel. The starch cells, therefore, 

 not being completely filled, give to the kernels a hard and 

 flinty texture and a rather dark color. In the Pacific 

 Coast States, where soft wheats are produced, rather 

 little rain falls during the growing season, but it falls in 

 abundance during the winter, and since the soils of this 

 section have great water-holding capacity, the plant is well 

 supplied with moisture during its full period of growth. 

 Some of the difference in the physical characters between 

 hard and soft wheats may perhaps be due in part to a 

 difference in the size of the starch cells, as revealed by 

 microscopic examination, those of the soft wheats being 

 the larger. 



116. Adaptation to soil. In addition to its adaptation 

 to climate, wheat will grow well under greatly varying 

 soil conditions. The soil, unlike climate, has no notice- 

 able effect upon the quality of the grain, but it is of con- 

 siderable importance when the yield is considered. Like 

 almost all crops, wheat yields the best on fertile soils, 

 although good yields may be secured on rather poor types 

 of soils if proper fertilization and cultural methods are 

 employed in growing it. As a general thing, wheat is 

 better adapted to the so-called " grass lands " or clay 

 loam soils, than to the more fertile " corn soils " that are 



