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<p>This study investigates the genetic variation and growth performance of <i>Eucalyptus urophylla</i> progenies under water stress conditions in tropical regions, with a focus on early selection. A progeny test was conducted with 43 open-pollinated progenies and two commercial clones in Grajaú, Maranhão, Brazil. The Köppen climate classification is Aw (tropical with dry winter), with an average temperature of 27&#xa0;°C and annual rainfall below 1100&#xa0;mm, concentrated in the summer months. Evaluations were carried out at 29 and 42 months of age, measuring survival rate, diameter at breast height (DBH), total height, and tree volume. The average survival rate was 77.49%, and correlations between growth trait evaluations at the two ages were higher than 0.80, indicating the efficiency of early selection under severe water stress during the establishment phase. Despite the low heritability values—highlighting the strong environmental influence on the measured traits—some individuals outperformed the commercial clones. However, the average growth of the progenies remained below that of the best-performing clone, a typical outcome in the early stages of breeding programs. In this case, early selection proved effective under water stress conditions, even though other studies have suggested the need for longer evaluation periods.</p>

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Early selection in Eucalyptus urophylla progenies under water stress conditions in tropical regions

  • 期刊论文

  • 发表日期：

    2025年9月30日

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  • Franciele Alves Menês,
  • Paulo Henrique Müller da Silva,
  • Guilherme Nichele da Rocha,
  • Andrei Caíque Pires Nunes,
  • Rodrigo Andrade de Furlan,
  • Cristiano Moraes

摘要

This study investigates the genetic variation and growth performance of Eucalyptus urophylla progenies under water stress conditions in tropical regions, with a focus on early selection. A progeny test was conducted with 43 open-pollinated progenies and two commercial clones in Grajaú, Maranhão, Brazil. The Köppen climate classification is Aw (tropical with dry winter), with an average temperature of 27 °C and annual rainfall below 1100 mm, concentrated in the summer months. Evaluations were carried out at 29 and 42 months of age, measuring survival rate, diameter at breast height (DBH), total height, and tree volume. The average survival rate was 77.49%, and correlations between growth trait evaluations at the two ages were higher than 0.80, indicating the efficiency of early selection under severe water stress during the establishment phase. Despite the low heritability values—highlighting the strong environmental influence on the measured traits—some individuals outperformed the commercial clones. However, the average growth of the progenies remained below that of the best-performing clone, a typical outcome in the early stages of breeding programs. In this case, early selection proved effective under water stress conditions, even though other studies have suggested the need for longer evaluation periods.