Importância das interações cultivares x locais e cultivares x anos na avaliação de milho na safrinha

Abstract

e LUIZ ANDRÉ CORRÊA 5 RESUMO -Com o objetivo de verificar a importância da interação cultivares x locais e cultivares x anos e de identificar entre os híbridos já disponíveis os que sejam mais adaptados e estáveis para o cultivo em safrinha, foram estimados os parâmetros de adaptabilidade e estabilidade a partir de dados obtidos em experimentos de avaliação de cultivares de milho na safrinha, nos anos de 1993, 1994 e 1995 Termos para indexação: interação genótipos x ambientes, estabilidade, adaptabilidade, melhoramento. IMPORTANCE OF CULTIVARS X LOCATIONS AND CULTIVARS X YEARS INTERACTIONS IN MAIZE EVALUATION IN THE "SAFRINHA"ABSTRACT -Aiming to check the importance of cultivars x locations and cultivars x years interactions, and to identify among the available hybrids those which are most adapted and stable for cultivation in "safrinha", the parameters of adaptability and stability were studied using the data previously obtained in some evaluation trials of maize cultivars in the "safrinha" during the years of 1993, 1994 and 1995. The experiments were conducted in the states of São Paulo, Goiás and Paraná, in Brazil. The experimental design utilized was in randomized blocks with 3 replications. It was verified that the magnitude of variation of the interactions of the cultivars x years inside the localities was more prominent than that by localities, indicating the necessity that evaluations of the cultivars in the harvesting period be accomplished in more years. The cultivars differed based on adaptability and stability of grain yield. The materials that distinguished themselves as more adaptable and stable were the simple hybrid Zeneca 8452, the triple hybrid C 805 and the double hybrid Agromen 2012. Now, the double hybrids BR 201, Planagri 411, AG 303 and C 125 were those that showed lesser adaptability and higher instability.

Alterations in heterosis of maize populations derived from single-cross hybrids after reciprocal recurrent selection

“…A similar experimental precision, assessed by the variation coefficient (VC%),was observed in both experiments: 24.92% and 22.18%, for populations 1 and 2, respectively. Consequently, the experimental precision was rated intermediate, as these estimates are close to others found in literature for maize trial (Scapim et al 1995, Ribeiro 1998, Gonçalves et al 1999. This precision allowed the identification of significant differences among progenies, suggesting, as expected, the existence of variability, which is confirmed by the frequency distributions presented in Figure 1.…”

Influência Da Irrigação E Cobertura Morta Do Solo Sobre as Características Agronômicas E Produtividade De Milho

“…A produção de milho, no Brasil tem-se caracterizado pela divisão da produção em duas épocas de plantio. Os plantios de verão, ou primeira safra, são realizados na época tradicional, durante o período chuvoso (Gonçalves, 1999). Mais recentemente, tem aumentado a produção obtida na safrinha, ou segunda safra.…”

Stability of combining ability effects in maize hybrids

“…Given the diversity of environments in which maize is cropped in Brazil, the hybrid by environment interaction is normally expressive (Aguiar et al, 2003;Gonçalves et al, 1999;Machado et al, 2008). Therefore it is necessary to identify hybrids that present not only wide adaptation, assessed by the mean yield, but also have high stability, i.e., with homeostasis to adjust to environmental changes.…”