INHERITANCE IN THE BARLEY SPIKE. 



19 



Table III. — Homozygous plants of selection 448-9 of the Hanna-Zeocriton cross, F± 



generation. 



F«line. 



Number of 

 individuals. 



Mean. 



Coefficient of 

 variability. 



448-9-4 



63 



16 

 59 



Millimeters. 

 2. 06 ±0.01 

 3.41± .04 

 4.30± .02 



6.80±0.41 



448-9-19 



7.33± .87 



448-9-30 



4.65± .29 







The mean of 448-9-19 is not as reliable as of the other two lines, 

 as only 16 individuals were available for the study. 



Selections 448-7 and 448-13 appear heterozygous in the F 3 genera- 

 tion and have about the same degree of frequency range. The coeffi- 

 cients of variability are much smaller than in F 2 , but are significantly 

 larger than in the pure parental forms. The frequency range for 

 448-7, of which 39 plants were studied, was from 2.0 to 3.2 mm. 

 Two plants from each of these lines gave evidence of being homozy- 

 gous in F 4 . These are shown in Table IV. 



Table IV. — Homozygous plants of selections 448-7 and 448-13 of the Hanna-Zeocriton 



cross, F t generation. 



F« line. 



Number of 

 individuals. 



Mean. 



Coefficient of 

 variability. 



448-7-1 



107 

 102 

 64 

 57 



MiUimeters. 

 2. 21 ±0.01 

 3.12± .01 

 3.19± .02 

 4.15± .02 



7.69±0.35 



448-7-3 



5.77± .27 



448-13-2 



6.27± .37 



448-13-5 



4.58± .29 







Four of the 20 F 2 plants which were tested in F 3 appeared to give 

 homozygous progeny. Three of these proved to be homozygous by 

 further test, while one, 448-11, proved heterozygous. The F 4 lines of 

 interest which seem to be homozygous are shown in Table V. 



Table V. — Homozygous plants of selection 44S-11 of the Hanna-Zeocriton cross, F t 



generation. 



F t line. 



Number of 

 individuals. 



Mean. 



Coefficient of 

 variability. 



448-11-2 



73 

 45 



Millimeters. 

 3.08±0.01 

 3.69± .02 



5.52±0.31 



448-U-3 



4.34± .31 







The three lines of especial interest which appeared homozygous by 

 both the F 3 and F 4 study are as follows: 448-1, mean 2.30 ± .01 mm.; 

 448-5, mean 2.88 ±.01 mm.; 448-16, mean 4.30 ±.01 mm. The F 4 

 generation means are given for these lines, as they are based upon 

 larger numbers than the F 3 test. Typical spikes of the parent 

 varieties and of these lines are shown in Plate II. 



