Inheritance of Rest Period of Seeds in the Peanut


zero rest period. Rest period is thus expressed over only about
one-half of its genetic range. This possibility may be checked
in the breeding behavior of pure strains whose modal type is
zero and the entire theory may now be examined in this and
other details.
 It seems desirable first, however, to consider briefly alterna-
 tive explanations of rest period expression. One is that after-
 ripening proceeds at a nearly constant rate until it is about
 one-half completed. It then becomes, very suddenly, enormously
 accelerated and rushes to completion in a time so short that
 it cannot be distinguished from zero by the present methods.
 Other explanations might involve complex gene interactions
 which produce little or no effect with less than about 50 percent
 of the total gene number and behave in a usual manner with
 higher numbers. These possibilities cannot be entirely ignored.
 They are dismissed for the present on the grounds of being
 less plausible than the first plan outlined.
 Extreme dominance of short rest period, coupled with the
one-sided expression of errors which must be obtained at or
near zero, might account for the apparent skewness of frequency
distributions of rest period. Any apparent necessity of the
genetic range of rest period transgressing below the zero point
of the physical character might thus be eliminated. Very
strong super-dominance or complete dominance with replicate
genes would be necessary to recover a parental phenotype in
50 percent or more of F3 and F4 seeds from a multigenic cross,
as is the case in the cross 1 x 14, Table 4. The case for dom-
inance breaks down in the further summary of that cross in
Table 5 where apparent skewness is highly correlated with
shorter rest period. Variable expression of dominance cannot
be easily accepted nor can dominance explain the regular and
greatly varied series of frequency distribution types. Tests of
rest period in F, seeds have been reported earlier, Stokes and
Hull (16), and additional tests are reported in Tables 3 and 6.
Slight dominance of long rest period or an intermediate F1 is
indicated. A total of 14 F1 seeds has been produced on Spanish
plants by pollination from runner plants and tested for rest
period. Every seed had a rest period of some length and con-
siderably in excess of the Spanish parents. Every seed was
harvested at the proper stage of maturity, was strong, plump,
and vigorous and was given a fair test. Earlier or later har-
vesting would have shortened the rest period. Time from plant-