208 THE WHEAT PLANT 



rainfall occurs during the early part of the growing season, a few good 

 showers alternating with bright sunshine and a dry atmosphere resulting 

 in the highest yield of grain of fine quality. In addition to a suitable 

 climate, a deep rich soil containing an abundance of humus and an 

 adequate supply of lime, potash, and phosphates is necessary to secure 

 the best returns. 



The Macaroni Wheats are highly resistant to rust and smut fungi. 



In Australia, where wheat is frequently utilised as a hay crop, some 

 forms of T. durum have proved of especial value for this purpose. The 

 Macaroni Wheats, however, are grown chiefly for their grain, the best 

 samples of which are yellowish, translucent, and very hard and difficult 

 to grind. In modern mills the grains undergo a process of " conditioning " 

 before being ground. 



In Russia and some other parts of the world a large amount of durum 

 is used for bread-making, either by itself or mixed with 10-20 per cent 

 of flour of Red-grained Bread Wheat ( T. vulgar e). The bread made from 

 Macaroni Wheat is yellowish in colour, but of excellent flavour, and keeps 

 fresh longer than that from Bread Wheat. 



The high gluten-content and the physical quality of the protein of 

 these wheats make them specially suited to the manufacture of macaroni, 

 spaghetti, and other edible pastes, and large quantities are employed for 

 this purpose, especially in France, Italy, and Spain. For the preparation 

 of these pastes the grain is milled only as far as the " semolina " stage, a 

 finely grained flour not being required. The dough formed from the 

 semolina is subsequently forced through tubes or openings of various 

 forms and sizes and then dried. 



GENERAL CHARACTERS OF T. durum 



The young leaf-blades and shoots have almost always the erect 

 " spring " habit (Fig. 65) ; I have seen none with the low spreading 

 " winter " habit, and a few only in which the young leaf-blades are semi- 

 erect, making an angle of 45-6o with the soil surface in the early stages 

 of their growth. 



The leaves, which may be yellowish-green or bluish-green, are all 

 glabrous in most varieties. In a small number of forms, which are 

 probably hybrids, short hairs are present, especially on the surfaces of 

 the lower leaves, the character of the hairs in some cases suggesting an 

 affinity with T. vulgar e, in others a relationship with T. dicoccum or T. 

 turgidum (Fig. 137). 



The culms are striate, from 75 to 150 cm. or more (about 30-60 inches) 

 high, the surface somewhat dull and slightly rough ; in some cases they 

 are hollow with thick walls, but in most varieties they are solid throughout 



