18 VALUE OF FIKST-GENEEATION HYBRIDS IN CORN. 



and with crossbred stocks of the original variety. Reduced to bushels 

 per acre and placed in tabular form, the yields reported by Shull were 

 as follows: 



Strain A, eelf-fertilized 23. 5 bushels. 



Strain B, eelf-fertilized 25. bushels (estimated). 



AXB 74. 4 bushels. 



BX A 78. 6 bushels. 



General average of crossbred stock 75. bushels. 



From Doctor Shull's standpoint the important point in the above 

 comparison is the increase of 1.5 bushels per acre which the average 

 of the crossed pure strains shows over the average of the cross-pollinated 

 original stock, an increase of 2 per cent. 



At the same time a comparison was also made between the yield of 

 self and cross pollinated ears of the same isolated strain. The yield 

 from the cross-pollinated seed was 30 per cent greater than that from 

 the self-pollinated ear. As an instance of the increased vigor of the 

 first-generation hybrid this example is of interest, since it indicates 

 that an increase in yield follows the crossing of even the most closely 

 related plants. 



To many producers of corn it will appear hardly practicable to 

 apply this system on a commercial scale. Neither does it appear 

 reasonable on theoretical grounds to look on these anomalous self- 

 fertilized strains as representing the natural condition. It would 

 seem that even the most advantageous combinations might be found 

 without reducing the varieties to the verge of extinction before the 

 cross is made. 



But no method of investigation should be rejected for purely theo- 

 retical reasons. Until other experimental data are available the 

 effect of previous breeding upon the vigor of the hybrids must remain 

 an open question. The importance of the subject demands that all 

 the phases shall be considered, and those who hold to the conception 

 of "bio types" and ''pure germ cells" will do well to experiment 

 along the lines suggested by Doctor Shull. 



EXPERIMENTS IN CONNECTICUT. 



A more extensive series of crosses was made by Dr. E. M. East at 

 the Connecticut Agricultural Experiment Station. His results are 

 stated as follows: 



The Fi generation of 30 maize crosses were grown in 1908 on well fertilized land in 

 Connecticut. They were planted 3 feet 6 inches each way, about foiu- stalks to the 

 hill. Seeds from the same parent earso which were used to make the crosses were 

 also grown for comparison. Only 50 hills of each of the crosses and of each parent 

 could be grown on account of limited space, but the soil conditions were such that a 



a "The parent ears were, therefore, one year older, but their germination was good, 

 and their growth equal to inbred seed of the same ages as the hybrid seed." 

 191 



