Two methods of seed preparation were compared in the production of a double-cross hybrid. One method consisted of preparing the seed by making individual-plant reciprocal crosses. The other method consisted of crossing reciprocally several plants from the female row to the respective single plant (of the male row) that was used in the individual-plant reciprocal cross.

The second method was designated as the bulked source since seeds from several female plants were bulked. Single ears from the individual-plant method were kept separately.

There were 72 pairs of plots in the experiment (equivalent to 72 replications). The statistical analyses were performed to maximize the chance of detecting differences between the two methods. However, only plant height and yield of the 15 characters studied exhibited significant differences for the two methods of seed preparation. These differences were small. Thus, there is evidence that differences attributed to cytoplasmic effects on agronomic characters in previous studies were not due to method of seed preparation.

J. Keith Contarino and A. A. Fleming

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