140 



BREEDING CROP PLANTS 



to quality but the yield was low. Johnson (1919), of the Wiscon- 

 sin Agricultural Experiment Station, attempted to overcome this 

 objection by breeding. In 1909 a pure-line study revealed the 

 fact that there were no less than three distinct morphological 

 types present in the particular variety, grown at the experiment 



FIG. 30. Tobacco No. 27. A pure line strain with a high leaf number and a 

 low breadth index of leaf. (After Johnson, 1919.) 



station, which was introduced from Connecticut. Selections 

 No. 26 and "No. 27 differed distinctly from the normal or prevailing 

 type. Form 26 carried fewer leaves but of larger size than the 

 normal, while form 27 possessed more leaves which were some- 

 what smaller in size than the normal. A cross between 269 

 and 27 cf was made in 1910 with the hope of combining the 

 desirable features of the two forms. The success of the cross is 

 indicated in the following data taken from Johnson. 



