Perennial teosinte-Gaspe hybrids: selection for maizoid characters

As part of the plan whose aim is to select maizoid plants from hybrids between perennial teosinte and maize, selection was started in 1982. Maizoid plants of an F2 population originating from the crossing between Zea perennis and Gaspe were selected, harvesting grains produced by free pollination. They initiated in 1983 the F3 select maizoid (F3SM) progeny, made up of approximately 70 plants. A number of specific or agronomically important characters were evaluated in the F3SM. The studied traits were: days to tassel (T), days to silking (S), days to pollen (P), pollen grain size (PGS), pollen fertility (PF), tassel branch number (TBN), tassel branching axis length (TBAL), tassel central spike length (TCSL), lateral tassel branching internode length (LTBIL), lowermost tassel branch length (LTBL), stalk diameter (SD), number of tillers (NT), number of leaves (NL), leaf width (LW), leaf length (LL), number of productive nodes (PN), number of ears in the uppermost node (EUN), and number of ears per tiller (ET). In the same way some ear traits, such as ear type, spikelet type, kernel type and number of kernel rows, were evaluated. The studied traits were used to compare F3SM with F2 and F3 populations, the latter coming from Z. perennis and Gaspe crosses in which no selection was made.

Tables 1-4 show the results obtained. Selection for maizoid characters had a positive result, because the F3SM population stands out significantly for most of the characters over the non-selected F2 and F3 populations. Maizoid plants of the F3SM population stand out for their high vigour and they present most of the maize-specific characteristics: high number of tassel branches, long tassel branching internodes, big pollen grains, paired female spikelets and naked kernels. Likewise, maizoid plants have thick stalks, low number of tillers, wide and long leaves, and they are highly productive.

Table 5 shows the significant correlations between characters. Most of the specific traits are associated. It means that selection based on a few maizoid characteristics implicitly leads to an indirect selection of those strongly associated traits. Maizoid plants stand out for their high prolificity. Selection on these types of plants in hybrids between perennial teosinte and maize progeny may have great practical importance to be used directly or indirectly in the improvement of maize production.

The results obtained point out a positive answer to selection. This encourages great expectancy to obtaining high productivity maizes by means of wild germplasm utilization.

Table 1: Evolutive cycle. T-- days to tassel; S-- days to silking; P-- days to pollen.

Table 2: Tassel branching and pollen traits.TBN-- tassel branch number. TBAL-- tassel branching axis length; LTBIL-- lateral tassel branching internode length; PF-- pollen fertility; PGS - pollen grain size.

Table 3: Number of leaves (NL) number of productive nodes (PN) number of ears in the uppermost node (EUN) and ears per tiller (ET).

Table 4: Ear traits

Table 5: Phenotypic correlation coefficientsbetween characters of F3 SM plants. (*)-- Significant at 5% level; (**)-- Significant at 1% level.

Gabriela Pischedda and Jorge Luis Magoja

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

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