It is very well known that the wild relatives of maize have a kernel protein content 2 or 3 times greater than maize (see MNL 59:61, 1985). As was previously published (MNL 59:69, 1985), the F2 and F3 progenies derived from crossing perennial teosinte (Zea perennis) and maize there is a high protein content, which is dominant, and is given by the wild parent of the cross (Z. perennis). This fact led us to believe that possibly the teosintes, or perennial teosinte in this particular case, could be used to improve the kernel protein content in maize.
A perennial teosinte introgressed population of maize was studied to find out the effect played by perennial teosinte germplasm on protein content (see MNL 61:66,
Table 1. Whole kernel protein content of a perennial teosinte introgressed
population of maize.
|Year||Mean t SD||Range|
|1986||13.5 ± 1.3||11.4-15.1|
|1987||12.4 ± 1.6||8.8-15.4|
1987). It is important to point out that the introgressed population is indistinguishable from conventional ones as all the plants essentially resemble the phenotype of cultivated maize, the only difference being the high prolificity and variability attributed to the effects of wild germplasm introgression.
During two years running, a plant sample was taken at random from the introgressed population, and then the chosen individuals were evaluated through different morphological traits and by their kernel protein content. Table 1 summarizes the results obtained for kernel protein content. As can be seen, the average values obtained are not too high, though they are greater than control average values. When we correlated protein content with 12 plant and ear traits, statistically significant associations were not detected: for example, prolific vs. nonprolific plants or high yield vs. low yield plants do not differ significantly between themselves in their kernel protein content. This fact let us budget that plant selection by kernel protein content perhaps does not significantly affect agronomically important traits.
As the population studied does not show a great difference in mean kernel protein content, relative to the controls used (11%), the relatively high variability existing for this trait in the introgressed population could eventually permit a selection cycle on high protein content. The most outstanding individuals have up to 50% higher protein content than commercial maize, and this fact can be attributed to the effects of wild germplasm introgression.
While mean kernel protein content of the introgressed population is lower than that found in progenies derived from interspecific hybrids (see MNL 59:69, 1985) it is useful to remember that those plants were morphologically very similar to teosinte, and had a lot of little spikes each with small kernels. On the other hand the actually studied material is essentially maize, and consequently the increasing of protein content in a great deal of individuals belonging to that population is considered significant, showing the positive effect of wild germplasm introgression on the expression of the studied traits.
Liliana A. Perini1 and Jorge L. Magoja
1Fellow, Com. Inv. Cient. (CIC), Prov. Buenos Aires.
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