PLANT GENETICS 



25 



AR 



AW 



BR 



Female 



gametes 



AR 



AW 



BR 



BW 



BW Male gametes 



Collecting the various combinations we obtain: 



^'2 PLANTS Ft BREEDING HABIT 



1 AARR Awnless, red seed. Will breed true for awnless spike and red 



2 ABRR Int. awns, red seed. Will segregate for spike character and 



breed true for red seed. 



2 AARW Awnless, red seed. Will breed true for awnless spike and 



segregate for seed color. 



4 ABRW Int. awns, red seed. Will segregate for both seed color and 



spike habit. 



1 AAWW Awnless, white seed. Will breed true for awnless spike and 



white seed. 



2 ABWW Int. awns, red seed. Will segregate for spike habit and breed 



true for white seed. 



1 BBRR Bearded, red seed. Will breed true for bearded spike and 



red seed. 



2 ABRR Int. awns, red seed. Will segregate for spike habit and breed 



true for red seed. 



1 BBW W Bearded, white seed. Will breed true for bearded spike and 



white seed. 



Several Factors Necessary for the Production of a Character. 



In many cases several factors are involved in the production of a 

 single character. Thus the purple aleurone color found in Black 

 Mexican sweet corn is dependent on the interaction of the factors 

 R, C, A, and Pr (see Chapter XII, Maize Breeding). C and A are 

 basic factors both of which must be present for the development 

 of color. When R, C and A are present the color in the aleurone 

 layer is red. Let us study a cross between Black Mexican which 

 is homozygous for purple aleurone color and a white sweet which 

 is homozygous for factors R and A but which lacks the factors C 



