YIELDS OF FIEST-GENEEATION HYBEIDS. 



29 



by dividing the total weight of the ears produced in the row by the 

 number of phmts. The plants w^ere started four in a hill and thinned 

 to one as soon as established. 



Table IV. — Yields per plant of 16 corn hybrids compared with that of their parents. 



Name of hybrid. 



Ah3, Maryland dent by Hopi 



Ah4, Tuscarora by Cinquantino 



Dhl, Kansas dent by Chinese 



Dh2, Chinese by Chihuahua 



Dh3, Hopi by Chinese 



Dh4, Chinese by Xupha 



Dh6, Brownsville by Chinese 



Ehl, Hopi by Algerian pop 



Gh2, Tom Thumb by Quezaltenango black. 



Kh31, Brownsville by Guatemala red 



Kh62, Guatemala red" by Salvador black . . . 



Mhl3, Quarentano by Brownsville 



Mhl5, Huamamantla by Hairy Me.xican. . . 



MhKi, Arribeiio by Hairy Mexican 



Mhl7, Hairy Mexican by Chinese 



Mh25, Mexican dent by Tom Thumb 



Average percentage of increase of hy- 

 brids over average of parents 



Yield of 

 female 

 parent. 



Pounds. 

 1.19 

 .53 

 .99 

 .39 

 .74 

 .39 

 .77 

 .74 

 .10 

 . 77 

 .31 

 .27 

 .40 

 .39 

 .18 

 .52 



Yield of 



male 

 parent. 



Average 

 yield of 

 parents. 



Pound. 

 0.74 

 .24 

 .39 

 .69 

 .39 

 .63 

 .39 

 .34 

 .10 

 .31 

 .27 

 .77 

 .18 

 .18 

 .39 

 .10 



Pound. 

 0.965 

 ..385 

 .690 

 .540 

 .565 

 .510 

 .580 

 .540 

 .100 

 .540 

 .290 

 .520 

 .290 

 .285 

 .285 

 .310 



Yield of 

 hvbrid. 



Pounds. 



1.25 

 .75 



1.09 

 .95 



1.28 

 .54 



1.16 

 .91 

 .42 

 .49 

 .33 

 .48 

 .31 

 .47 

 .61 

 .54 



Percentage 

 of increase 

 of hybrid 



over 



average of 



parents. 



Per cent. 



29 



95 



58 



76 



126 



6 



100 



69 



C) 



(a) 



-9 

 14 



-8 



7 



65 



114 



53 



a Where the yield of either parent fell as low as 0.10 pound per plant the percentage of increase of the 

 hybrid is omitted. In dealmg with these small quantities it is believed that percentages would be 

 misleading. 



Before leaving the subject of increased yields in firet-generation 

 hybrids it may be well to summarize the results of the experiments 

 bearing on this question. 



To carefully canvass the literature of agriculture for all references 

 to the yield of first-generation hybrids would be a large undertaking, 

 and it is not pretended that the present summary is complete. It is 

 believed, however, that the experiments cited, which are all that have 

 come to the writer's attention, establish the wide application of the 

 principle and give a fair indication of its importance. 



Beal (Michigan, 1878-80) in two crosses very carefully compared with the parent 

 varieties secured an increase in both cases, the average increase being 31 per cent. 



Another cross by Beal (1882) compared with the best parent exceeded that parent 

 by 21 per cent. 



Ingersoll (Indiana, 1881) in a cross between two strains of the same variety secured 

 an increase over the male parent of 95 per cent. 



Sanborn (Maine, 1889) in one cross secured an increase over the average of the 

 parents of 41 per cent. 



Morrow and Gardner (Illinois, 1892) secured increases in eight out of nine crosses, 

 the average increase being 11 per cent. 



Shall (New York, 1908) by first inbreeding and then crossing got an increase over 

 the original mixed stock of 2 per cent. 



East (Connecticut, 1908) secured increases in all of four crosses, the average increase 

 being 73 per cent. 

 191 



