100 COHN CROPS 



" elementary strains that nick well," plants from the best 

 ear remnants could be used for inbreeding for the purpose 

 of securing pure strains. There is more chance of secur- 

 ing strains that will cross well from these ears than when 

 plants are taken at random. After pure strains had been 

 secured that would cross to advantage as determined by 

 experiment, these strains would be grown from year to 

 year in isolated fields and used each j^ear to produce 

 first-generation hybrid seed. 



SUMMARY 



73. No fixed relation has been found between type and 

 yield. The largest well-matured ears growing under 

 normal conditions of soil and stand should be used for 

 seed. Large ears with a medium depth of grain usually 

 mature better than large ears with a very deep grain. 



Mass selection and pedigree selection will ultimately 

 give similar results when visible characters are chosen, 

 as height of ear or shape of ear ; but with invisible char- 

 acters, as ability to yield, results are not so sure with 

 mass as with pedigree selection, and at best they will 

 come slowly. 



Pedigree selection involves the testing of each ear sepa- 

 rately for yield, by planting a part. The remnants of 

 best ears may be used directly as a foundation stock and 

 the progeny may be continued in some system of ear-to- 

 row selection. The very highest values will be secured 

 by systematic crossing of the best strains. 



