108 



CORN CROPS 



had been inbred for five years and appeared to he pure 

 strains, were compared with the original com. The table 

 also summarizes results with four strains of Leaming 

 inbred by East, and a combination of several strains of 

 Hogue's Dent inbred by Montgomery : — 



TABLE XVI 



' Ann. Rpt. Amer. Breeders Assoc, Vol. VI: 63-72. 1909. 



2 Conn. Agr. Exp. Sta., Bui. 168. 1911. 



s Nebr. Agr. Exp. Sta. Ann. Rpt. 1912 : 183. 



It is evident from these data that the immediate effect 

 of seK-fertilizatibn is to reduce the yield, the greatest 

 reduction taking place the first year. 



The amount of decrease seems to differ with varieties, 

 or even with strains of the same variety. In general, 

 inbreeding will decrease yield to about one-half the first 

 year. Continuing the inbreeding will in some cases 

 reduce the yield to one-fourth the original yield, while 

 in other cases, inbred strains become entirely sterile. 

 Present experiments indicate that the yield is reduced 

 until the strain becomes a " pure strain," after which 

 inbreeding has no further effect in decreasing yield. 



Very often abnormal types appear in inbred strains. 



