Hayes and Garber - Cucurbit Breeding

288 BREEDING CROP PLANTS
report of a recent study at the Minnesota Station (Olson, Bull, and
Hayes, 1918), which contains experimental evidence together
with a review of other experiments in relation to score card
characters and yield, show no correlations between individual
characters 'such as trueness to the ideal score card ear type and
subsequent yield of these ears.
Artificial self-fertilization in corn isolates homozygous types
which are less vigorous than normally cross-pollinated plants.
All other evidence seems to show that too close a purity of
type corn tends to a reduction in vigor. The grower whose
method of selection is based upon ear type is certainly obtaining
no gain in yield of shelled corn per acre. The detrimental
results of too close selection to type may not be very apparent and
may be more than counterbalanced by the extra attention from a
cultural
standpoint, for an interest in ideal ear types certainly
stimulates the farmer to produce better corn. It is not, however
an increase due to better breeding but to better cultural practice.
The present purpose is to outline methods of seed selection. As
there is no apparent relation between score card characters for
type of ear planted (within a particular variety) and resultant
yield, even though such selection may be constantly practiced, we
may pay little attention to those characters as far as our breeding
plan goes. The grower should, of course, produce corn of one
variety which is pure, judged by easily evident characters, such as
color of seed and cob. Abnormalities, such as very large butts,
badly flattened cobs, or very irregularly rowed ears, should not
be used as foundation stock. Aside from these there is no need
of paying much attention to type. Ability of a variety to
mature under the conditions, is very important and needs much
attention.
Two methods of work are outlined here, either of which may be
of considerable value in increasing yield.
METHOD OF BREEDING CORN FOR SPECIAL BREEDERS
Nearly all discussions of corn breeding are based on the ear-torow
method. Such a method takes considerable time and can be
carried out only by the breeder or occasional seed specialist.
The ear-to row test is commonly understood. It consists of
growing the seed of a certain number of ears in individual rows
and determining the better yielding ones. Each ear saved is