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Research Bulletin (Iowa Agriculture and Home Economics Experiment Station)

Abstract

1. The character known as "germless" in maize is described. Data are presented on its occurrance and the manner of inheritance and linkage relations of the genetic factors causing the character, together with data on other linkage relations in group II.

2. It is shown that germless seeds commonly occur in our commercial varieties of corn.

3. Data are presented on the inheritance of two different factors, gm2 and gm1, which cause germless seeds.

4. Linkage relations of gm2 and gm1 with factors in linkage group II were determined.

5. The factor gm2 was found to be linked with R with 27.11 percent of crossing over as compared to 31 percent previously reported by Demerec (6).

6. The gm2 factor, however, did not show, in the F2 data, evidences of linkage with G or Pg1 . The lack of evidence of linkage with G is explained by assuming gm2 to be located to the left of R, while G has been shown by Lindstrom (9 and 10) to be located to the right of R with a crossover percentage of 20. The lack of evidence of linkage with Pg1 is explained in the same way after the presentation of data to show that Pg1 is also located to the right of R near G with 14.57 percent of crossing over between G and Pg1.

7. Data presented show no linkage between gm1 and r or c.

8. There is some evidence of linkage between gm1 and G but not sufficient to be conclusive.

9. Data on gm1 and Pr showed no linkage of these two factors.

10. Rather extensive data on R and Pr showed conclusively that there is no linkage between these two factors as reported by Hayes and Brewbaker (8).

11. Some data are also presented which show that there is no linkage between Pr and G.

12. Linkage data on R and G show a crossover percentage of about 20 which checks with data previously reported by Lindstrom (9 and 10).

13. The percentage of crossing over between R and Pg1 was found to be 23.39 which checks with Brunson's (3) data on these two factors.

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