DEVELOPMENT OF THE HETEROSIS CONCEPT 



61 



A25 X tester as 0. The results (see Table 3.14) indicate that gametes from 

 Golden King are a desirable source of improvement of A25 in crosses with 

 A73 X A375. 



From this first trial three high and three low yielding lines were selected, 

 and selfed progeny grown in Si. Plants in each of the three Si high and three 

 low combining lines were selected, selfed, and again top crossed on A73 X 

 A3 75. The agreement for So and Si lines was very good (see Table 3.15). 

 It appears that gamete selection is an excellent breeding method for the 

 early selection of material to improve the specific combining ability of a 

 known inbred. 



SOME GENETIC CONCEPTS OF HETEROSIS 

 It seems very evident to the writer that heterosis, the increased vigor of F] 

 over the mean of the parents or over the better parent, whichever definition 

 is "used, is not due to any single genetic cause. A brief summary of various 



TABLE 3.14 



DISTRIBUTION OF % MOISTURE AND YIELD OF 32 So 

 PLANTS OF A25XG. KING CROSSED TO A73XA375. 

 CLASSES OF L.S.D. 5% AROUND MEAN OF A25X 

 TESTER 



%ear 

 mois. 



(mean of A25X 

 tester) 



Yield 

 (mean of A25X tester) 



TABLE 3.15 



PERFORMANCE INDICES OF So AND Si LINES 

 FROM A25XG. KING WHEN CROSSED TO 

 A73XA375 TESTER AND COMPARED WITH 

 A25XTESTER 



