Hayes and Garber - Cucurbit Breeding

202 BREEDING CROP PLANTS
Kempton were made with widely different varieties, the results
are probably somewhat more striking than if more closely related
forms had been used.
FI Varietal Crosses. The utilization of hybrids as a means
of obtaining more vigorous types was urged by Beal (1876-1882).
Since then there has been frequent mention of the vigor of
FI crosses, and Morrow and Gardner (1893, 1894) outlined a
plan for the production of crossed corn seed. Renewed interest
in this subject was aroused as a result of the publications of East
FIG. 46. Minn. No. 13 high protein strain No. 4. Short, erect strain with
light green leaves. Produces good ears. Tassels are plentifully supplied with
pollen.
(19086) and Shull (1908, 1909) on the effects of inbreeding and
cross-breeding, and of Collins (1909, 1910) on the value of first
generation hybrids in corn. Many experiments in which first
generation crosses have been compared with their parents have
been made. In Table XL IX only those varietal crosses are used
in which the ^i has been compared with both parents.
A careful study of this table shows that first generation crosses,
on the average, yield more than the average of their parents.
In many cases the cross exceeds the higher yielding parent.
No