Estabilidade de produção de híbridos simples e duplos de milho oriundos de um mesmo conjunto gênico

Abstract

Obteve-se a contribuição de cada híbrido para a interação genótipos x ambientes e o desvio em relação ao desempenho máximo em cada ambiente utilizando a estatística não-paramétrica por meio da soma de postos. Os híbridos duplos foram, em média, mais estáveis, contudo, identificaram-se híbridos simples tão estáveis quanto os duplos. Palavras-chave:Interação genótipos x ambientes, Estatística não-paramétrica, Zea mays L. ABSTRACT YIELD STABILITY IN SINGLE AND DOUBLE CROSSES OF MAIZE ORIGINATED FROM THE SAME GENE POOLThe objective of the present work was to study the adaptability and stability of single and doublecrosses of maize originated from the same gene pool. Ten commercial single-crosses and all possible double-crosses, obtained from a complete diallel, were evaluated. Seeds of the double-crosses were obtained in an experimental area of the Biology Department at Universidade Federal de Lavras (DBI/ UFLA). The experiments were conducted in 15 environments in the 2005/06 growing season, on farms and in experimental stations. The cultural practices were the ones normally used by farmers or experimental stations for maize. The entries were evaluated in randomized complete blocks design with three replications per environment. The trait under study was husked ears yield (kg ha -1 ), corrected to 13% of moisture content. Nonparametric statistics were used to study hybrids adaptability and stability. The contribution of each hybrid to the genotype-by-environment interaction and the deviation in relation to the maximum performance in each environment was determined. The double-crosses were on average more stable, although some single-crosses were as stable as the double-crosses.

Stability of combining ability effects in maize hybrids

“…To verify whether the estimates of the general and specific combining abilities were different from zero, the t test was carried out (Zhang et al, 2005). Nonparametric statistics were used to obtain a measure of the stability of the parameters of the Griffing diallel analysis, base of the contribution of each estimate to the genotype by environment interaction (Machado et al, 2008;Truberg & Huehn, 2000).…”

“…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.…”

Factor analysis using mixed models of multi-environment trials with different levels of unbalancing

“…The data used in this study has been previously described by Machado et al (2008). Experiments were conducted in nine environments during the 2005/06 agricultural year at experimental stations and farms (Table 1).…”

Productive potential and castor bean selection of the FCA-PB cultivar progenies

“…Progenies 1,5,6,8,15,18,19,21,27,31,35,36,38,45,49,55,56, and 58 exhibit a certain level of stability with productivity at over 2100 kg ha -1 , in different cities and crops, being selected by these aspects, and can be used to obtain new cultivars and hybrids (Machado et al, 2008). Rev.…”