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BREEDING CROP PLANTS 



general rule can be given and the only sure means of determining 

 the value of a cross is by the experimental test. Results have 

 shown that FI crosses between good yielding varieties which 

 differ from each other in several characters frequently yield con- 

 siderably more than either parent and more than pay for the 

 trouble of producing crossed seed. Thus the tests made in Con- 



FIG. 47. Fi cross of Minn, self-fertilized strains No. 1 X No. 4. 



necticut (Jones et al, 1919) and those carried out in Minnesota 

 (Hayes and Olson, 1919) showed thatFi crosses between selected 

 eight-rowed flints and dents very frequently exceeded either 

 parent in yielding ability. For each growth character in which 

 the parent varieties differ there is usually an intermediate condi- 

 tion in FI. There is a tendency for a partial dominance and the 

 first generation often exceeds the average of the parents in most 



