Early selection in open-pollinated Eucalyptus families based on competition covariates

Abstract

-The objetive of this work was to evaluate the influence of intergenotypic competition in open-pollinated families of Eucalyptus and its effects on early selection efficiency. Two experiments were carried out, in which the timber volume was evaluated at three ages, in a randomized complete block design. Data from the three years of evaluation (experiment 1, at 2, 4, and 7 years; and experiment 2, at 2, 5, and 7 years) were analyzed using mixed models. The following were estimated: variance components, genetic parameters, selection gains, effective number, early selection efficiency, selection gain per unit time, and coincidence of selection with and without the use of competition covariates. Competition effect was nonsignificant for ages under three years, and adjustment using competition covariates was unnecessary. Early selection for families is effective; families that have a late growth spurt are more vulnerable to competition, which markedly impairs ranking at the end of the cycle. Early selection is efficient according to all adopted criteria, and the age of around three years is the most recommended, given the high efficiency and accuracy rate in the indication of trees and families. The addition of competition covariates at the end of the cycle improves early selection efficiency for almost all studied criteria.Index terms: Eucalyptus, intergenotypic competition, progeny tests, selection methods. Seleção precoce em famílias de polinização aberta de Eucalyptus com base em covariáveis de competiçãoResumo -O objetivo deste trabalho foi avaliar a influência da competição intergenotípica em famílias de polinização aberta de Eucalyptus e o seu efeito na eficiência da seleção precoce. Foram realizados dois experimentos, nos quais o volume de madeira foi avaliado em três idades, em delineamento de blocos ao acaso. Dados dos três anos de avaliação (experimento 1, aos 2, 4 e 7 anos; e experimento 2, aos 3, 5 e 7 anos) foram analisados a partir de modelos mistos. Foram estimados: componentes de variância, parâmetros genéticos, ganhos com a seleção, número efetivo, eficiência da seleção precoce, ganho com a seleção por unidade de tempo e coincidência de seleção com e sem uso de covariáveis de competição. O efeito da competição não foi significativo em idades inferiores a três anos, e o ajuste por covariáveis de competição foi desnecessário. A seleção precoce para famílias é eficiente; famílias de hábitos de crescimento tardio são mais vulneráveis à competição, o que prejudica de forma mais pronunciada a sua classificação ao final do ciclo. A seleção precoce mostra-se eficiente de acordo com todos os critérios adotados, e a idade em torno de três anos é a mais recomendada, em razão da alta eficiência e do alto índice de acerto na indicação de árvores e famílias. A adição de covariáveis de competição ao final do ciclo melhora a eficiência da seleção precoce para quase todos os critérios estudados.Termos para indexação: Eucalyptus, competição intergenotípica, testes de progênies, métodos de seleção.

Intra-and intergenotypic competition among commercial eucalyptus clones

“…The VOL and MAI traits had higher environmental coefficients of variation than the other traits. This result is expected since they are based on other variables, such as DBH and H (Scarpinati et al 2009, Pavan et al 2011, Pavan et al 2014, Pupin et al 2015).…”

“…To disrupt genetic uniformity, the use of mixtures of clones may increase productivity and benefit individuals in the face of biotic and abiotic stresses, due to unknown interactions that occur between genotypes (Martins et al 2014). These interactions can result in different forms of competition, which have a variable effect on genotype performance, as each genotype has specific competitive capacities (Pavan et al 2011, Pavan et al 2014. Competition can be classified as intragenotypic, when it occurs in monoclonal stands, or intergenotypic, when it occurs in polyclonal stands (Perecin et al 1997).…”

Selection in the First Year of Passion Fruit Production: A Potential Strategy for Breeding

“…However, the implementation of the selection of promising genotypes should be performed in the first year to reduce the costs of implementing the breeding program, allowing the selection of plants in the first year and the recombination of genotypes in the second year of production, as recommended by the methodology of recurrent selection. For Eucalyptus spp., with a rotation age of 7 years in tropical regions, Beltrame et al (2012) and Pavan et al (2014) suggest the early selection of hybrid clones in the third year after planting, maximizing the genetic selection gain with the same financial resources and human resources available. Rosal et al (2000) reported that the early selection of families of bean were effective, especially in the elimination of the worst families, thus reducing the work of breeders in advanced generations.…”

Early selection in Eucalyptus camaldulensis Dehnh. progenies in Savanna, Brazil

“…The efficiency of early selection is allied to the high correlation of characteristics assessed at juvenile age and rotation age (Ferreira, 2005). Studies assessing the feasibility of early selection model for the Eucalyptus genus demonstrate the possibility of this practice (Chaves et al, 2004;Massaro et al, 2010;Lima et al, 2011;Beltrame et al, 2012;Apiolaza et al, 2013;Denis and Bouvet, 2013;Moraes et al, 2014a;Pavan et al, 2014;Pinto et al, 2014;Costa et al, 2015;Tambarussi et al, 2017).…”