Section IV, 1918 [69] Trans. R.S.C. 



The Inheritance of the Length of the Flowering and Ripening Periods 



in Wheat. 



By W. P. Thompson, Ph.D. 

 Professor of Biology, University of Saskatchewan. 



Presented by J. H. Faull, Ph.D., F.R.S.C. 



Contents. 



1. Introduction. 



2. History. 



3. Materials. 



4. Experimental Results. 



1. Ripening Period. 



(1) First Hybrid Generation. 



(2) Second Hybrid Generation. 



2. Flowering Period. 



5. Discussion and Conclusions. 



1. Apparent Dominance in F.l. 



2. Failure of Multiple Determiner Hypothesis of Blending. 



3. Economic Applications. 



6. Summary. 



7. Literature Cited. 



1. Introduction. 



In genetical studies on the ripening period of wheat we have to 

 do with a case of blending inheritance and the related fundamental 

 problem of the constancy of the Mendeiian determiners. The special 

 value of the material lies in the fact that we have many parental 

 races differing by many degrees in regard to the character- in question. 

 Any hypothesis of blending inheritance can therefore be tested much 

 more thoroughly than in cases where only pairs of parental types are 

 available. An hypothesis, which may satisfactorily explain the re- 

 sults of crossing variety A with variety E, can be much more thorough- 

 ly tested when we also have the result of crossing A with B, B with C, 

 C with D, A with C, etc., where B, C and D are intermediate between 

 A and E. The experiments reported in the following pages have been 

 planned with this consideration in mind. 



The problem, of course, has very great economic possibilities, 

 particularly for Western Canada. A necessary characteristic of all 

 annual plants grown in the Western provinces is the possession of a 

 very short period of maturity. Many crops cannot now be grown 

 there at all because sufficiently early varieties do not exist. And 

 many crops now grown frequently suffer from frost or are totally 



