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GENETIC VARIABILITY OF MAIZE THREE-WAY CROSS HYBRIDS FOR TROPICAL RUST RESISTANCE

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Author(s): MARIA ELISA AYRES GUIDETTI ZAGATTO PATERNIANI | CHRISTINA DUDIENAS | EDUARDO SAWAZAKI | REGINALDO ROBERTO LÜDERS

Journal: Revista Brasileira de Milho e Sorgo
ISSN 1676-689X

Volume: 1;
Issue: 1;
Start page: 63;
Date: 2002;
Original page

Keywords: maize | top cross | inbred lines | Physopella zeae | resistance sources

ABSTRACT
Three-way cross hybrids from the Agronomic Institute Campinas (IAC) maizebreeding program were evaluated for tropical rust resistance caused by Physopella zeae, infield conditions. Two experiments of top crosses, derived from crosses between two testers(experimental single-cross hybrids A and B) and IAC and CIMMYT (Centro Internacional deMejoramiento de Maíz y Trigo) lines were carried out. A randomized complete-block designwas used, with three replications, evaluating in each experiment 30 three-way cross hybrids, the respective testers and three commercial checks. Both experiments were cultivated in Guaira,in the north region of São Paulo State, under high natural presence of tropical rust. Theevaluations were performed 30 days after flowering, according to a scale of notes from 1 to 9,corresponding to: 0% to >75% affected leaf area in the adult plant. In TC 1, showed to beresistant (notes from 3,0 to 4,4) 30% of the three-way cross hybrids and 43% was moderatelyresistant (notes from 4,5 to 5,4). In TC 2, this proportion was inverted, that is, 43% of thethree-way cross hybrids showed to be resistant and 33% moderately resistant. The combinedanalyses of variance of the three-way cross hybrids with common lines did not detect significantdifferences, indicating that additive effects predominated for resistance to P. zeae. It was identifiedsome resistant lines which could be utilized to generate synthetics with high resistance to P.zeae, in maize recurrent selection program for tropical rust resistance.
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