USES OF CEREALS 555 



flour, 13 per cent or more, while it may run from 10 to 

 12 per cent in family flour. 



600. Increasing the protein content of wheat. It 

 is now rather generally agreed that a pure strain of wheat 

 cannot be improved in protein content by selection alone, 

 though such improvement is possible by the production 

 of new strains through hybridization. Moreover, it is 

 shown by Le Clerc, Thatcher, and others that protein 

 content is not a heritable character, but an immediate 

 effect of the environment. The greater effect is from cli- 

 matic conditions, though a difference in soil structure 

 affecting the water supply has much influence. Appar- 

 ently the usual cause of an increase of protein is a shorten- 

 ing of the fruiting period. The matter may, therefore, 

 sometimes be somewhat under the control of the grower. 

 For example, late seeding of spring wheat, or, in Califor- 

 nia, practically spring seeding of winter wheat, will 

 shorten the fruiting period by delaying the time of flower- 

 ing, with much less corresponding delay of the time of 

 ripening (289, 315-317). 



601. " Yellow Berry " in wheat. The same condi- 

 tions just discussed should explain the presence of so- 

 called " yellow berry," though there has been some dif- 

 ferences in views expressed on this subject. The yellow 

 kernels in a flinty wheat are mealy, like soft wheats, have 

 a dull yellowish color, and contain less nitrogen. Such 

 kernels may occur in spots in the same field with hard 

 glutinous wheat. Headden (1915) believes the matter 

 may be controlled in the use of fertilizers. Some condition 

 possibly occurs lengthening the fruiting period, thereby 

 decreasing the proportion of gluten to starch. It may be 

 noted that the protein content of wheat is higher under 

 dry-farming than on irrigated farms, and when a variety 



