STUDIES ON OAT BREEDING. 1 01 



cally and, as Johannsen proved in the case of beans, practically 

 it is not possible to improve such a pure line by further selection. 



The question as to whether it is possible to improve a pure 

 line of oats by continued selection has been studied by this Sta- 

 tion for several years. The results of three years of such selec- 

 tions have been published. 6 It has been shown that selection 

 for three years both to increase and to decrease certain charac- 

 ters has not modified any of the characters studied. 



The results of this work are of much importance to the prac- 

 tical oat breeder. It .follows that in order to secure improved 

 strains it is only necessary to select individual plants from the 

 commercial fields and then to multiply the seed of each plant 

 separately. Then each of these pure lines must be tested and 

 only the best retained. After a desirable pure line has been 

 isolated it is only necessary to keep it pure and unmixed with 

 other seed. Such a pure line will not deteriorate nor can it be 

 improved by further selection. This greatly simplifies the 

 methods of practical oat breeding. It has been shown that it 

 io useless to continue the expensive methods of selecting year 

 after year within a pure line. In order to get still better yielding 

 strains it is necessary to go back to commercial fields and make 

 new selections with the hope of isolating still better pure lines. 

 Once a pure line is isolated it cannot be improved by further 

 selection. 



Of course, at any time and for reasons at present unknown, 

 germinal variations may occur within a pure line and these may 

 breed true to their new characters. If plants showing such 

 germinal variations should be selected it would be possible to 

 secure strains showing characters different from the parent 

 pure line. While there is good evidence that such germinal vari- 

 ations do occur in oats, they are relatively rare. Practically, 

 there seems to be very^ little chance of securing such variations 

 from a pure line. (cf. pp. 142-143.) 



B Surf ace, F. M. and Pearl, R. Studies on Oat Breeding. II. Selection 

 within pure lines. Maine Agr. Expt. Stat. Ann Rept. 1915, pp. 1-40. 

 (Bulletin No. 235). 



