Breeding of Wheat. 



23 



existence. Further, the cultivation of a long series of hybrids 

 between heavy and comparatively low yielding- wheats seems 

 to point to segregation of these features. Exact statistics, 

 however, are very difficult to obtain owing to the wide range of 

 fluctuating variability in this character and the difficulty of growing 

 plants under sufficiently uniform conditions to eliminate this. 

 Even when the outer rows of an F. 2 culture are neglected as con- 

 sisting of obviously favoured plants, gaps, due to failures in 

 germination or the attacks of mice, &c, give neighbouring plants 

 a greater root range and better opportunities for development than 

 others. In the absence of such information one has to fall back on 

 the yields of the plots grown from the F. 2 generation and then on 

 the crops of succeeding years, basing conclusions as far as possible 

 on plots of sufficient acreage to give trustworthy returns. For 

 this purpose the Fife hybrids mentioned previously are fairly 

 suitable, as under the conditions under which these experiments 

 were made Fife barely yields twenty bushels to the acre, whilst 

 Rough Chaff may be expected to give a good average yield of 

 thirty-two bushels. 



In making the selections for further cultivation these strong 

 types, promising to give the best yield, were deliberately chosen. 

 Some forty of these, which have been tested in plots varying from 

 one-quarter to three acres in extent, have given in each case yields 

 of the same order as the parent Rough Chaff and over 50 per 

 cent, greater than Red Fife on the same farm. On other soils 

 some grown on the large scale have produced crops of forty-two 

 to forty-four bushels, but in these cases the cropping capacity of 

 Rough Chaff is unknown, though Fife is known to be a failure 

 as regards yield. The evidence for the segregation of high and 

 low yields is by no means final, but it is sufficient to show that 

 high yields of good quality are not unobtainable. 



The question of heavy yields per acre is intimately connected 

 with the power of resisting the various diseases to which the 

 wheat crop is liable, as no plant crippled by the attacks of a 

 parasite can be expected to yield its full quantity of grain. It is a 

 well-known fact that if a large number of varieties of any plant 

 grown under the same conditions are exposed to the same chances 

 of infection they show marked differences in the extent to which 

 they become attacked by various parasites. This is well shown 

 in the case of wheats and the various rusts which live upon them. 

 In fact, it has now become part of the routine work of many 

 experimental stations to collect and grow as many varieties as 

 possible, with the view of selecting the most immune types for 

 local cultivation. In our earlier tests several varieties were found 

 showing an extraordinary power of resisting the attacks of the 

 common yellow rust, Puccinia glumarum. Even in years when 



