Heterotic responses of maize hybrids containing alien germplasm

A synergistic effect, observable as a significant increase in yield, has been measured in several maize hybrid lines, each of which carried a different introgressed segment of genes from teosinte plus a short chromosomal segment from Tripsacum. These results are just part of the data collected from a three-year yield trial at Waltham. F1 hybrids were produced the summer before their being planted in the trial. Data were collected by lines, blocks and replications as shown in Table I.

By summing the data from the three trial replications, the yield of each of the 24 different lines can be compared. This tabulation is presented in Table II. As can be seen by the means in Block 1, the differing amounts of teosinte germplasm have a significant effect in altering the yields about the mean of the control, 1.13 Kg. This becomes more evident in Block 2, but even more pronounced in Block 3 which contains the Tr-7 monosomic chromosomal segment.

The control mean (line h) in Block 3 is 1.82 Kg which is almost identical to the control mean of Block 2. It should be noted that these are the lines that have no introgressed teosinte present. However, in lines b, c, and d, which contain various teosinte segments plus the Tr-7 segment, the yield is higher than the related lines in Block 2 which have no Tripsacum. In other cases, such as in line g, the Tripsacum seemed to have made little if any difference.

A Duncan's Multiple Range test will be run on all of the line means and a more complete ANOVA covering 12 other dependent variables is yet to be done. Correlations between an increase in prolificacy and yield will also be studied.

Table I.

Table II.

Joel I. Cohen

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors.

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