Garber and Quisenberrv : Origin of False Wild Oats 



269 



Relation Between Fatua Types and 



Delayed Germination in the 



Second Generation 



In order to determine whether the 

 fatua type was closely associated in in- 

 heritance with delayed germination, the 

 second generation plants were classified 

 on the basis of seed articulation, as 

 fatua-like, intermediate, or sativa-like 

 forms. The segregation in the second 

 generation clearly indicated that a sin- 

 gle factor difference controlled the type 

 of seed articulation. Of all the crosses 

 (including all i)lants whose seeds were 

 not tested for germination), there were 

 110 fatua-like, 354 intermediate, and 

 124 sativa-like plants with regard to 

 seed articulation (P. = 0.458). A 

 correlation coefficient indicated linkage 

 between type of seed articulation and 

 percentage of germination for the 

 second generation progeny of each 

 cross was prepared. The tables were 

 arranged so that a significant positive 

 correlation coefficient indicated linkage 

 between the fatua type of seed articula- 

 tion and delayed germination. These 

 correlation coefficients are presented in 

 Table III. 



All the coefficients except one in 

 Table III are significant, and they 

 show that in the second generation in- 

 dividuals delayed germination was as- 

 sociated to some extent with the fatua 

 type of seed articulation. The magni- 

 tude of the coefficients, however, also 

 shows that close linkage l)etween these 

 two characters did not exist. The low- 

 est correlation (r = +0.159 10.086), 

 was obtained in the progeny of the 

 cross Yellow wild oat X Victory, and 

 the highest correlation (r = +0.538 

 * 0.048) was obtained in the F^ prog- 

 eny of the cross, Garton 748 X Yellow 

 wild oat. 



High percentages of germination 

 were frequently obtained from second 

 generation plants with fatua seed char- 

 acters. This is shown by the data in 

 Table IV. The frequency distributions 

 with respect to the percentage of germ- 

 ination of the fatua-like seeds for all 



the second generation |)rogenies are 

 shown. Only plants which produced 

 seed with fatua-like articukitions on 

 both the primary and secondary seeds 

 are considered in this group. There 

 is a distinct accumulation of individuals 

 at the upper limit of the distributions. 

 Considering all the crosses, approxi- 

 mately one-third of the fatua-like 

 ]ilants produced seed which germinated 

 from 95 to 100 per cent. 



Linkage is indicated by the number 

 of significant correlations obtained be- 

 tween the fatua-like second generation 

 segregates and delayed germination. On 

 the other hand a considerable number 

 of these second generation segregates 

 showed no delayed germination. These 

 facts which are brought out in Tables 

 III and IV indicate that in the fatua- 

 sativa crosses reported in this paper 

 delayed germination was linked with 

 the fatua-like seed articulation. l)ut the 

 linkage was not close. 



Germination of False Wild Oats 



The homozygous and heterozygous 

 false wild oats as well as the sativa 

 forms reported below came from the 

 same stock as those previously report- 

 ed (Garber, 1932).'* The progenies of 

 heterozygous false wild oats showed 

 segregation similar to that obtained 

 previously. The segregation from 

 heterozygous plants obtained in this in- 

 vestigation was as follows : 



46 Victory, 74 heterozygous false 

 \"ictory, 54 homozygous false Victory ; 

 38 Garton 784, 84 heterozygous false 

 Garton 784, 34 homozygous false Gar- 

 ton 784 ; 357 Aurora and heterozygous 

 false Aurora, 76 homozygous false 

 Aurora. 



The phenotypes of Aurora and het- 

 erozygous false Aurora were so similar 

 that no attempt was made to place 

 them in a separate group. In general 

 heterozygous false Aurora possessed a 

 degree of awn development somewhat 

 greater than that of pure Aurora but 

 the dift'erence was not marked. 



The data in Table V show that there 

 was no striking difference in seed 

 germination among the various forms 



