During the growing season 1984/85, small populations of F1 individuals from the cross between diploperennial teosinte (Zea diploperennis) and a sweet corn variety (Evergreen), and both parents, were cultivated in separate plots. A series of traits was evaluated on a sample of F1 hybrid plants taken at random. Results are summarized in Table 1. Excepting those traits belonging to the cycle time, the rest show a considerable variation between F1 plants derived from the same cross. It is possible that this is a consequence of the expression of different F1 genotypes.
Likewise the expression of specific traits such as tassel central spike type, ear type and female spikelet arrangement is not uniform, though with the predominance of one of the possible states of each trait. The results obtained point out that the inheritance of those traits by which maize is distinguished from teosinte cannot be attributed to simple genes unless, as is probable, a strong modification is caused by the genetic background of each particular hybrid. As was previously communicated (MNL 59:68) the expression of specific traits in other hybrids between diploperennial teosinte and maize was different. This fact let us suppose that each particular type of maize can have a different influence on the expression of specific traits in the hybrids obtained. The most conspicuous aspect in these hybrids is the enormous heterosis that they reveal, which is mainly expressed through a greater number of productive nodes, ears per tiller, ears per plant and plant yield, over the average of their parents (Table 2).
Yield and prolificacy have a high heterotic expression. Highly significant increase of productivity per plant, not only relative to the parental average but to the higher yield parent, results.
This particular fact lets us suppose that diploperennial teosinte constitutes a genetic resource of great value, which can be used in projects whose objective is the increasing of yield of those cultivated species.
The heterotic expression of those traits of economical importance such as yield can be detected early in F1 individuals. Although these plants do not join appropriate agronomical characteristics, to be directly cultivated, the additional generated heterosis can be availed in projects of controlled introgression, as communicated in this issue.
I.G. Palacios and J.L. Magoja
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