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20 
Journal o f Agricultural Research 
Vol. XXIX, No. I 
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Fig. 1.—Frequency distribution, by dates of heading, of F 2 hybrids 
and of the Kota and Hard Federation parents at Davis, Calif., St. 
Paul, Minn., and Mandan, N. Dak., in 1922 
In the present study 
comparisons of Fj with 
parents are not available, 
butF 2 data compared with 
those from parent plants 
are available from three 
sources. Only at Davis, 
Calif., were reciprocal 
crosses studied for this 
character. The frequency 
distribution obtained is 
given in Table XIII and 
shown graphically in Fig¬ 
ure 1. In the background 
of Plate 2 are shown the 
labeled plants growing at 
Davis, Calif. The dates of 
heading were obtained by 
tagging the plants indi¬ 
vidually on the day the 
first head emerged from the 
sheath. The average dates 
of heading for the F 2 
hybrids and for the parents 
are given in Table XIV. 
At Davis, Calif., the crop 
was fall sown and during 
the ideal spring conditions 
the dates of heading of the 
parents extended over a 
period of 26 days. The F 2 
hybrids headed there dur¬ 
ing 18 of these days, as 
shown in Table XIII and in 
the upper portion of Fig¬ 
ure 1. Earliness in the F 2 
progeny appears partiaky 
dominant as the mode is 
nearer that of the early 
parent than of the late one. 
The reciprocal crosses at 
Davis show slight maternal 
influence. The mean dates 
together with their proba¬ 
ble errors are as follows: 
Kota X Hard 
Federation, 
April_- 29. 65 ±. 10 
Hard Federa¬ 
tion X Kota. 
April_ 29. 13 ±. 07 
Difference_ . 52 ±. 12 
This difference of 0.52 ± 
0.12 days,while small, is sig¬ 
nificant as it is 4.3 times its 
probable error, with odds of 
267: 1 against the occur¬ 
rence of such a difference 
being due to chance alone. 
With earliness dominant 
and present in the female 
parent, the slight maternal 
influence is exerted in the 
same manner as in the case 
of color of glumes and color 
of kernel. 
