Hayes and Garber - Cucurbit Breeding

196 BREEDING CROP PLANTS
corn and gave 2.5 per cent, higher protein content. These
particular strains, 1 and 4, were not examined during the seedling
stage and consequently it was not then known that strain 1 was
heterozygous for the white seedling chlorophyll abnormality
which Lindstrom has designated by the factor w. In the second
generation grown from self-fertilized ears of A, B, and K, approximately
one-fourth of the seedlings were pure white. Lindstrom
has shown that plants heterozygous for the chlorophyll
factors Ww are slightly less vigorous than homozygous green
forms. These facts lead one to expect that high protein races
with good yielding ability may be produced. On the other hand,
FIG. 44. Two high protein strains of Minn. No. 13 at left and right respectively
which have been self-fertilized for five years and first generation cross between
them in the center. The F\ yielded slightly more than normal Minn. No. 13 and
analyzed 2^ per cent, higher in protein content.
maximum yield of grain and high protein content probably can
not be obtained in the same variety.
CORN IMPROVEMENT BY THE TRAINED PLANT BREEDER
A uniform technic has been developed for the small-grain breeder.
With corn, however, the correct method of breeding is even yet
somewhat problematical. Investigations have helped to clarify
our ideas regarding the value of different methods of wcrk.
For the farmer the results obtained have tended to simplify previous
ear-to-row methods. For the technical breeder, however,
the application of Mendelian principles has resulted in
several plans, some of which appear rather complex. Their