DISTINCTIONS IN CULTIVATED BARLEYS. 



DATE OF RIPENING. 



The date of ripening is a note universally taken. While less 

 dependable than the emergence of the awns, it is a very useful obser- 

 vation. Within a strain the plants mature quite uniformly. In 

 order to determine the amount of such variation, the exact date of 

 maturity of each spike in a plat of Manchuria barley was recorded. 

 The spikes were considered ripe when the last traces of green dis- 

 appeared from the glumes. In order to avoid confusion, they were 

 harvested as fast as they ripened. The result is shown in figure 6. 

 The curve is very sharp, almost half the product of the plat maturing 

 upon the same day. 



The weakness of the note is 

 in the abnormal ripening of va- 

 rieties. In Minnesota the ob- 

 servation is quite dependable in 

 Manchuria forms, but is likely 

 to be much less so in the 2- 

 rowed varieties. Some of the 

 latter mature in a normal man- 

 ner, while others, especially the 

 later ones, half ripen and half 

 die. Also, a rain at this period 

 has much more influence in the 

 development than at other times 

 in the life of the plant. 



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Fig. 6. — Curve showing the ripening of 

 1,541 spikes in a plat of Manchuria bar- 

 ley, stated in days from date of planting. 



COMPARATIVE RATES OF DEVELOP- 

 MENT. 



Although separations can be 

 made by a study of any one of 

 these stages, it is only when the 

 entire seasonal histories of the 

 selections are compared that the full variation is apparent. Figure 7 

 shows the development of 14 strains from the production of the 

 second leaf until maturity. Each stage was obtained by actual count 

 of all the normal plants in each centgener, usually between 90 and 100. 



The relation of the earlier stages has already been commented upon. 

 It will be noticed that the tillers are produced usually after the 

 fourth leaves. In Nos. 34, 13, and 24 this is not the case, and these 

 three selections are definitely distinct from the other eleven by this 

 different habit of tillering. Nos. 21 and 57 are parallel in the earlier 

 stages but are widely separated in the emergence of the awn. No. 29 

 is one of the earliest of all the selections to produce the second leaf, 

 52783°— Bull. 137—14 2 



