Hayes and Garber - Cucurbit Breeding

METHODS OF BREEDING SMALL GRAINS 117
Clausen, 1918) and is now being tried by other investigators.
consists of growing a bulk plot of the cross for several generations.
At the end of from six to ten years, head selections may be made
with the knowledge that a large part of these selections will breed
true. The adoption of this plan will in a large measure do away
with the technic of studying individual plants in a heterozygous
population. It is desirable for those workers who would like to
use crossing methods but who do not have time for individual
plant studies. It is not so rapid as the Mendelian method.
Technic of Harvesting, Thrashing, Etc. Slight variations in
methods are used by different workers. At Cornell rows of
like kind are taken to the thrashing shed and hung head down
until thrashed. At the Minnesota Station the straw is cut near
the base, the bundles tied with the stake, label near the bottom,
and the heads wrapped with a cheese-cloth covering. Bundles of
the same selection are then tied upright to a stake and later taken
to the thrashing shed when needed. The row trials at the substations
are harvested by cutting off the heads. These are then
put into cloth sacks and shipped to the Central Station.
Several machines which can be cleaned easily have been devised
for thrashing. The chief requisites of a machine to be used for
experimental purposes are that it be easily cleaned and that so far
as possible there be no ledges or ridges upon which seeds may
lodge. The alternate thrashing of different nursery crops is a
desirable procedure. Each of the plots of one strain of wheat may
be thrashed separately in rotation and then a strain of oats may
be thrashed in the same way. At the Minnesota Experiment
Station winter wheat is thrashed alternately with barley and
spring wheat with oats. This plan helps materially to reduce
the roguing of accidental mixtures from the plots.
Various machines have been made to assist in individual head
and plant thrashing. A machine constructed by H. W. Teeter,
of the Department of Plant Breeding at Cornell (Love and
Craig, 1918a), is very satisfactory. As no screen or fan is used,
all seeds are saved. After thrashing, the seed is passed through
a wind blast. This machine is so arranged that mixtures may
be avoided.
It