Yield and yield components of full sib and half sib families derived from a perennial teosinte introgressed population --R. Burak and J. L. Magoja As part of a recurrent selection cycle from a perennial teosinte (Z. perennis) introgressed population of maize, during the 1987/88 growing season, full sib and half sib families derived from such populations were evaluated in Llavallol. These families and controls (commercial hybrids) were part of an augmented randomized complete block design cultivated at a 57,143 pl/ha density.

The average yield of the full sib families was of 6,912 ± 1,711 kg/ha (range: 1,811 to 15,471), while that of the half sib families was of 8,600 ± 2,500 kg/ha (range: 1,800 to 17,900).

When the yield was correlated with 27 other characters of agronomic importance, measured both in the full sib and the half sib families, it was found that yield was significantly associated with only 8 characters.

As is shown in Table 1, the yield seems to depend on the plant height, the prolificity and the size and weight of the ears and kernels.

Table 1. Phenotypic correlation coefficients between grain yield and some traits.

Even if the greater part of these families are prolific, this being the character which can be taken as the most evident sign of introgression, the number of ears per plant is not always the principal yield component. While it seems that in the half sib families the kernel yield mostly depends on the prolificity rather than on other characters, in the full sib families prolificity as well as size and weight of ears seem to have similar importance to condition the yield.

When studying those families with greater yield in depth, it could actually be proven that in some of such families, the high kernel yield could be attributed, basically, to the production of one (sometimes two) big and heavy ears. In most cases the high kernel yield of the families depends especially on the production of several (multiple) ears of acceptable size. If the biological efficiency can be measured through kernel production per plant under certain cultivation conditions, it is evident that within this introgressed maize there are different ways of achieving it: through prolific individuals (most cases) or through non-prolific. This fact is another element which contributes to document that, within the wide yield ranges, even in the positive extreme the variation persists (high yield due to one or several ears).

The genetic and/or physiological yield bases are not yet well known, thus being sometimes difficult to foresee advances in the yield improvement as a consequence of a certain kind of plant. In spite of that, in the particular case of this introgressed maize there still exists the hope of achieving the production of greater yields, maybe through the possibility of combining genotypes that condition high yield through different ways (with or without prolificity).

It cannot be said what might result from these combinations, but probably this kind of experience might lead to a better understanding of which factors condition a greater biological efficiency.

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