86 



From the above review of the principles recognized in connection with 

 plant improvement work at Svalof, it will be seen that all possible ways of 

 reaching the desired end are employed. Line-breeding from old races, artificial 

 cross-fertilization and mass-selection each occupy a place, and may indeed be 

 regarded as the tripod of progression in the scientific breeding of plants. 



Practical Importance of Sort Purity. 



The experience of the men both at the Scientific Station and at the 

 Seed Company at Svalof has amply demonstrated the great practical 

 importance of sort purity. Many farmers, however, do not regard purity 

 as a matter of great concern, but continue to use impure seed from year to 

 year. A brief consideration of this question should be appropriate here. 



Definition of Tedin (67, p. 142) defines a sort as "a group of plants all possessed of the 



a 'sort. ' same botanical and constant characters which distinguish it from all other sorts 

 or races. If a group cannot fulfill these conditions it is not a sort but a mixture 

 of two or more such." Since the main object of breeding work is to produce 

 new and better sorts and since a true sort represents a definite and charac- 

 teristic entity, different in certain essential regards from all other sorts, it is 

 of great importance that its purity and therefore its identity be maintained. 

 Especially is this the case in brewing barley. The ability to recognize a sort 

 is important from a purely commercial standpoint, as it prevents misrepre- 

 sentation, fraud and all the serious consequences which may follow. Concrete 

 instances of. how this power to identify a sort may operate, are on record at 

 Svalof. Mixed races may not only be troublesome to the breeder who must 

 keep a close check on all leading sorts under cultivation, but they may become 

 a source of much annoyance and trouble to those who buy seed. The farmer 

 who grows his own seed may not regard the question of purity as of great 

 importance. Certainly it is not impossible for an impure sort to give good 

 returns for a year or two or even longer. When one considers, however, the 

 rapidity with which the number of distinct biotypes or strains may become 

 augmented by an occasional natural crossing between them the danger of 

 such practice will become apparent. Since such forms are often found to 

 display differences in regard to date of ripening, size of kernel, per cent of 

 hull, strength of straw, etc., although perhaps not strikingly apparent when 

 growing together, it is not difficult to anticipate the possible losses that may 

 accrue. Sort purity to the farmer, is therefore quite as important as to the 

 commercial dealer and to the breeder, in fact it is upon the losses which the 

 actual grower may suffer that the chief significance of a pure condition, at 

 least in most crops, rests. In practice it has not been found possible to 

 maintain absolute purity. A certain margin of tolerance must therefore be 

 allowed. 



While the evidence seems strongly in favour of pure sorts, yet it is shown 

 that mixed or composite varieties may have their advantages under certain 

 circumstances. Thus a variety may contain strains which differ from each 

 other chiefly in their attitudes towards different conditions of soil and season. 



