430 



E. J. WELLHAUSEN 



as measured by the testers used, is higher among the more vigorous and 

 agronomically better lines. 



The experiment has been carried somewhat further. Inbreeding was con- 

 tinued in the various Si families originally classified a.s A, B, and C. After 

 three generations of selfing, the advanced lines on hand were topcrossed on 

 two different testers and the resulting topcrosses were tested for yield. On the 

 basis of average topcross performance, certain of the advanced inbred lines 

 were selected as worthy of keeping for further work. The number selected 

 from each of several varieties together with their classification is given in 

 Table 27.4. 



TABLE 27.3 



COMPARATIVE YIELDS OF A AND B S, LINES OF 



MICH. 21, PUE. 16, AND MEX. 39 IN 



TOPCROSSES WITH URQUIZA* 



* Urquiza was used as check. 



TABLE 27.4 



NUMBER OF LINES SELECTED FROM FOUR 

 VARIETIES ON BASIS OF TOPCROSS TESTS 

 AFTER THREE GENERATIONS OF IN- 

 BREEDING AND THEIR CLASSIFICATIONS 

 IN Si 



