8 CROSSBREEDING CORN. 



and some unusually poor producers. The indifferent and poor-pro- 

 ducing crosses were discarded and selection work started with the 

 unusually productive ones. As the work progressed some decreased 

 in productiveness while others retained their high-yielding qualities, 

 and a few have come mto general culture as the best grain-producing 

 strains of certain localities. 



As most of these crosses when tested in various localities were 

 found to be seldom superior to local strains, the improvement of 

 local strains by selection or by crossbreedmg and selection coni- 

 bined became a more prominent feature of the corn work. Tliis 

 feature has proved highly satisfactory and profitable to practical 

 farmers, and much experimental evidence has been obtained to 

 demonstrate that strains can be greatly increased in productiveness 

 by centgener selection. 



Investigations and observations have indicated a number of lines 

 for the improvement of general practices in seed-corn production. 

 In this coimection attention is called to the follo\ving points regardmg 

 corn: (1) That self-fertiHzation reduces productiveness; (2) that 

 constant isolation, especially when unaccompanied by judicious 

 selection, may result in the multiplication of undesirable individu- 

 als and the augmentation of their undesirable characters; (3) that 

 the emphasis which has unfortunately been placed upon the possi- 

 bihty of improvmg productiveness by planting fine-appearing, prize- 

 winning ears has reacted against the improvement of jdelds through 

 the selection of seed from high-yielding individuals; (4) that the 

 adaptation of the floral parts of maize to facihtate crossbreeding has 

 played an important part in its evolution, perhaps assisting in gi^^ng 

 it greater vigor, productiveness, adaptability, and freedom from 

 disease than other cereals. 



One or more of these features has reduced yields m so many 

 instances where increased yields were expected that some, and espe- 

 cially those who have not witnessed improvement by selection, have 

 become skeptical regarding possibility of increasing yields by selec- 

 tion and desirous of tryuig radically different methods. 



Crossbred seed frequently gives .better yields than either parent, 

 especially if one or both parents are i)oor producers as a result of 

 self-fertihzation, inl)reeding, or lack of atlai)tati()n or acclimatization. 

 Smce crossbred seed corn frequently yields less than one and some- 

 times less than either of the i)!ir(Mi( varieties, it would be very 

 unwise to advise the general planting of crossbred seed mthout 

 first demonstrating what varieties should be crossed in different 

 localities to produce seed of higher yielding ])Ower than that of the 

 best existuig strains. The profits that may result from following 



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