CONTENTS. 



Page. 



Introduction 7 



Personal exijlorations 9 



Characteristics and needs of the several wheat districts of the United States .. .9 



General needs of all the districts - 10 



Yielding power 10 



Early maturity 11 



Soft wheat district - 12 



Semihard winter wheat district 13 



Southern wheat district 14 



Hard spring wheat district 15 



Hard winter wheat district 17 



Durum wheat district - 18 



Irrigated wheat district 20 



White wheat district 22 



Sources for desirable qualities - - 25 



Characteristics of botanic groups of wheat 26 



Common bread wheats ( Triticum valgare) 26 



Club or square head wheats ( T. compactum) 28 



Poulard wheats ( T. turgidum ) 29 



Durum wheats ( T. durum) 30 



Polish wheats ( T. polonicum) - - - 32 



Spelt (T. spelta) ---- 33 



Emmer ( T. dicoccum) 34 



Einkorn ( T. monococcum ) 35 



Geographic groups of wheats - - - 36 



Improvements accomplished - 37 



Introduction of new varieties 38 



Work of the Department 40 



Wheat breeding 63 



Improvement by selection 64 



Improvement by hybridization 69 



Summary 77 



5 



