Hayes and Garber - Cucurbit Breeding

112 KREEDINd CHOP PLANTS
variety test. If its value is unknown it is handled in the plantbreeding
nursery. The three groups, introductions, selections,
and crosses, are given nursery class and stock numbers for means
of identification. The year of the first test in Minnesota is also
carried (except in the case of crosses where the year that the
cross was made is used), together with a series number from 1
to as many forms as are handled in the class for the year and
crop concerned. The following classes are used with the supposition
that the forms were first tested in the nursery in 1920:
Class 1-20-1, 1-20-2, etc
Class II-20-1, II-20-2, etc
Class III-20-1, III-20-2, etc
Selections.
Crosses.
New Introductions.
Supposing for example 20 new wheat introductions were grown,
these would be classed as III-20-1 to 111-20-20. All individual
plant selections are placed in class I if they are made from commercial
varieties or new introductions. The year that they are
first placed in the nursery is also carried, as well as the series
number. These class and series numbers are not changed as
long as the form is continued in the nursery trial.
Crosses are not given a series number until the strain gives
evidence that it is homozygous. For the first few years the
method of numbering used by the United States Department of
Agriculture is followed. Thus a cross made between 1-14-1 and
1-14-20 is labeled at the time of crossing 1-14-1 X 1-14-20.
The female parent is written first. On growing this cross
in FI a convenient number or letter is used. Later generations
for the letter method would appear as A for FI, AI for Fz,
A 11 to A-l-200 if 200 plant selections were grown in F 3 .
As soon as a cross is purified, that is, when particular selections
appear homozygous, they are placed in the rod-row test and given
a series number; thus the cross made in 1918 would be labeled as
follows :
First year,
Second year,
Third year,
Class 11-18, A
11-18, A-l
11-18, A-l-l to A-l-200
Suppose A-1-1Q and A-l-50 appear homozygous and look
promising, they would be placed in the rod-row test and receive
series numbers as II-18-1 and II-18-2.
Bank figuring books have been found to be quite satisfactory