CAMPINAS, SAO PAULO, BRAZIL

Instituto Agronomico
 
 

Resistance to Angoumois moth and corn weevil in husked ears --Luiz Eugenio Coelho de Miranda, Luiz Torres de Miranda and Sylmar Denucci In MNL 54:15-19 we reported on inheritance and linkages of multiple aleurone layering. Using ACRE 134, and AMAZONAS unnumbered collection, and Entrelacado from the same source, and a waxy source, versions with Mal, wx on our opaque-2 versions of IAC Maya and IAC 1 were obtained. The pedigrees simplified are Mal wx x IAC Maya o2(4) -o2 Mal wx and Mal wx x IAC 1 o2(4) -o2 Mal wx, Mal being "multiple aleurone layering". After the original cross and 3 backcrosses pure versions of o2 Mal wx were obtained. The original Mal collections are from a super humid very hot climate with no distinct dry season limiting for maize growing and optimum to insects. They are very badly adapted to our region down to pollen semi-sterility. In the beginning of June 5 ears of each entry of the acclimated material were husked and put in pairs touching in split plots, with their opaque-2 only versions on a shelf board, each pair about 30cm from the other in an ambient room condition. At the beginning of November the unholed and holed kernels were counted. The attack was by both Sitophilus oryzae or S. zeamais (Motschulsky), which are prevalent in our area, and Sitotroga cerealella (Oliver), not discriminating damage of one pest from the other. The data and analysis are presented in Table 1. For the IAC Maya the total effect of Mal over mal was +1.6±1.2, non-significant, but in the IAC 1 with +9.0±1.5, significant at P<0.01. In the 3 ears of each, which were better than the original opaque-2 versions, 11 grains each of both holed and unholed kernels were characterized in the number of aleurone layers by a third party. The results are presented in Table 2. Under binocular aleurone layer classification, a few kernels changed class, and that is why there are not equal numbers in unholed and holed classes.

Table 1. Number of unholed (U), and holed (H) grains in the pairs studied with the calculated relevant parameters.

Although we planted what we thought were pure Mal by analysis of 11 kernels per ear of selfed mothers, checking two or more layers, the readings gave initially 4 classes: 1) clearly only 1 layer, 2) with tendency to have more than 1 layer, 3) clearly 2 layers and 4) with more than 2 layers. By a contingency test in the 2x4 factorial it was seen that best results were gotten by pooling 1) with 2) and 3) with 4) (Table 2). Curiously for IAC Maya, which gave a lesser effect, now we have greater significant effects and vice versa for the IAC 1. It seems clear that now selecting within a population with variability, for the stabilization and enhancement of multialeurone expression, a much greater effect will probably be achieved since now we have a mean unholed % of 68.3±6.2 for 2 or more layers as opposed to the first total of 1, 3, 5, 6, 9, 10 of 23.8±1.0 in whole segregating ears, a difference of 44.5±6.3. Parallel populations with the factors were field tested for grain yield in 4 localities with 4 reps per place and in the fourth backcross, now to the normal endosperm, yielded in IAC Maya 87% and in IAC 1 119% in relation to their counterparts.

Table 2. Determination in the ear families 1, 3, 5, 6, 9, and 10 with Mal from Table 1 of the number of layers in the unholed (U), and holed (H) classes with the calculated relevant parameters. As seen, the families were not pure for multiple aleurone layering, perhaps because of environmental interaction effects.


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