60 



H. K. HAYES 



bining ability with (A334 X A340). As A357 is rather outstanding in com- 

 bining ability the result may not be so surprising. There was much greater 

 relation between the combining ability of F3 and F4 lines and of F4 with top 

 crosses than between F2 and F3. 



In an unpublished study of gamete selection, with a different but highly 

 desirable double cross, there was an indication that a lower yielding inbred 

 could be improved by an application of gamete selection (Stadler, 1944). 

 The study is from one phase of a breeding program to improve Min. 406. 

 The yield relations of inbreds in an average of single crosses are given in 

 Table 3.13. 



Approximately 60 Fi plants of A25 X Golden King were selfed and top 

 crossed with A73 X A375. Thirty-two of the more desirable plants were se- 

 lected to study in yield trials. In this study both yield and moisture classes 

 of plus 1, plus 2, etc. X L.S.D. at 5 per cent were used around the mean of 



TABLE 3.12 



COMBINING ABILITY RELATION OF F4 LINES OF 



(L317XA116) IN CROSSES WITH (A334XA340) AND 



WITH GOLDEN KING. GROWN IN 1949 



Total 



In 



A334 

 X 



A340 

 Crosses 



+ 1 -1 -2 -3 -4 -5 

 In Golden King Crosses 



1 

 1 

 6 

 1 

 13 

 8 

 1 

 2 



33 



TABLE 3.13 



GAMETE SELECTION IN THE IMPROVE- 

 MENT OF MINHYBRID 406 



(A25XA334)(A73XA375) 



Proposal for improvement of A25 and A73: 

 A25XG. King gametes 

 A73XMurdock gametes 



