380 E. L. PINNELL, E. H. RINKE, AND H. K. HAYES 



gametes as higher in general desirability than the sampler inbred parent. In 

 addition, gametes of low yield potential but of relatively satisfactory agro- 

 nomic characters were selected from both varieties, three from Golden King 

 and two from Murdock. 



Fo populations were grown in 1948 from the selfed ears of the twelve Fi 

 plants selected in the above manner. Visual selection was practiced for desir- 

 able plant and ear characters, and these individual plants were crossed to 

 the appropriate single cross tester. Remnant seed of the test crosses of the 

 selected Fi plants was used to make a direct yield comparison in 1949 with 

 the test crosses of the selected F. plants. Two randomized block experiments 

 were made at each of three locations in southern Minnesota with three 



TABLE 24.3 



GAMETE SOURCES, TESTERS USED, AND TEST CROSSES 



MADE IN SELECTING GAMETES FOR IMPROVEMENT 



OF INBREDS ASM, A25, AND A73 



Experi- 

 ment 

 Number 



1, 



2 



3 



4 



Inbreds 



A344 

 A344 



A344* 

 A344 



A25 



A73 



Gamete Source 



Tester 



Morris 13 gametes 



Inbred gametes 



A344 



Morris 13 gametes 



Inbred gametes 



A344 



Golden King gametes 



A25 



Murdock 



A73 



Number 



of 

 Crosses 



A357XA392 



A357X.\392 



A357XA392 



A357XA385 



A357XA385 



A357XA385 



A73XA375 



A73XA375 



A25XA334 



A25XA334 



35 

 8 

 1 



35 

 8 

 1 



32 

 1 



38 

 1 



* Same plants as in experiment 1. 



replications per location. One experiment consisted of the crosses of 6 Fi 

 plants (remnant seed) from A25 X Golden King, and 34 F-, plants by the 

 tester compared with the cross of A25 X tester. The other included test crosses 

 of 6 Fi and 37 Fo plants from A73 X Murdock gametes in comparison with 

 A73 X tester. 



EXPERIMENTAL RESULTS 

 The Morris strain of Minnesota 13 has been a very outstanding open- 

 pollinated variety in Central Minnesota for many years. Yield trial data 

 from plants of A344 X Morris 13 crossed with the testers show that a large 

 proportion of Morris 13 gametes have higher yield potential than A344. 

 Table 24 4 gives the distribution of yield and moisture data obtained from 

 thirty-five test crosses of A344 X Morris 13. Sixteen of the thirty-five gametes 

 gave test-cross vields significantly in excess of A344 X tester. Although not 

 higher in yield, five other gametes may be considered superior to A344 be- 



