Repeatability of Fruits and Seeds Production and Selection of Brazil Nut Genotypes in Native Populations in Roraima1

Abstract

-This study estimates the repeatability coefficients of two production traits in two native populations of Brazil nut trees. It determines the number of years of suitable evaluations for an efficient selection process, determines the permanent phenotypic correlation between production traits and also the selection of promising trees in these populations. Populations, located in the Itã region (ITA) and in the in the Cujubim region (CUJ), are both belonging to the municipality of Caracaraí, state of Roraima -Brazil, and consist of 85 and 51 adult trees, respectively. Each tree was evaluated regarding the number of fruits per plant (NFP) and fresh seed weight per plant (SWP), for eight (ITA) and five consecutive years (CUJ). Statistical analyses were performed according to the mixed model methodology, using Software Selegen-REML/BLUP (RESENDE, 2007). The repeatability coefficients were low for NFP (0.3145 and 0.3269 for ITA and CUJ, respectively) and also for SWP (0.2957 and 0.3436 for ITA and CUJ, respectively). It on average takes nine evaluation years to reach coefficients of determination higher than 80%. Permanent phenotypic correlation values higher than 0.95 were obtained for NFP and SWP in both populations. Although trees with a high number of fruits and seed weight were identified, more evaluation years are needed to perform the selection process more efficiently.Keywords: Bertholletia excelsa; Genetic improvement; Forest resources. REPETIBILIDADE DE PRODUÇÃO DE FRUTOS E SEMENTES E SELEÇÃO DE GENÓTIPOS DE CASTANHA-DO-BRASIL EM POPULAÇÕES NATIVAS EM RORAIMARESUMO -Os objetivos deste estudo foram estimar coeficientes de repetibilidade de dois caracteres de produção em duas populações nativas de castanheira-do-brasil, determinar o número de anos de avaliações adequado para um eficiente processo de seleção, determinar a correlação fenotípica permanente entre os caracteres de produção e selecionar árvores promissoras nessas populações. As populações, localizadas na região do Itã (ITA) e na região do Cujubim (CUJ), ambas pertencentes ao Município de Caracaraí, Estado de Roraima -Brasil, foram constituídas por 85 e 51 árvores adultas, respectivamente. Cada árvore foi avaliada quanto ao número de frutos por planta (NFP) e peso fresco de sementes por planta (SWP), por oito (ITA) e cinco anos consecutivos (CUJ). As análises estatísticas foram realizadas segundo a metodologia de modelos mistos, utilizando-se o Software Selegen-REML/BLUP (RESENDE, 2007 864Revista Árvore, Viçosa-MG, v.39, n.5, p.863-871, 2015 PEDROZO, C.A. et. al fenotípica permanente entre NFP e SWP acima de 0,95 foram obtidos nas duas populações. Apesar de ter sido possível identificar árvores com elevado número de frutos e peso de sementes, número maior de anos de avaliação é necessário para que o processo seletivo seja realizado de forma mais eficiente.

Repeatability coefficients and genetic gains in table grape progenies for the Brazilian semi-arid region

“…In contrast, high values of heritability for soluble solids content were observed in passion fruit (Santos et al, 2015). In general, the repeatability values observed in this study were higher than those mentioned for native perennial species such as bacuri (Maia et al, 2016b) and Brazil nut (Pedrozo et al, 2015). However, repeatability coefficients in grape were compatible to those mentioned by Leão and Costa (2003) and Cargnin (2016) for production, number of bunches, and bunch weight, but lower than those for soluble solids content.…”

“…The overall production average was 7.81 kg per plant, corresponding to estimated yield of 13 t ha -1 per growing season, considered low yield compared to the The estimated phenotypic variance between plants (Vfp) was greater than the estimated temporary environmental variance (Vet) for the variables of production, number of bunches, and berry diameter, indicating the possibility of success to select genotypes multiplied by vegetative propagation, conserving characteristics of superior genotypes selected. Nevertheless, the higher Vet values compared to Vfp values for the variables of bunch weight and soluble solids indicate that these two variables are highly influenced by environmental conditions, hindering selection of promising genotypes based on simple plant breeding methods, such as clone selection, and others that take into account only the individual phenotype (Pedrozo et al, 2015). Environmental influence on soluble solids content can be explained by the seasonal climate variations in the 1 st and 2 nd semester crop seasons in the São Francisco Valley.…”

“…This methodology has been widely used to estimate genetic parameters, select progenies, adaptability and stability. It is also used in breeding programs of perennial species, such as bacuri (Maia et al, 2016a), cajuí (small cashew) (Maia et al, 2016b), baru (Santos et al, 2014), Brazil nut (Pedrozo et al, 2015), passion fruit (Santos et al, 2015;Freitas et al, 2016;Silva et al, 2016), coffee (Rodrigues et al, 2013), peach (Bruna et al, 2012, and others. Nevertheless, references in the literature were not found regarding the use of this method in grape breeding.…”

Research Article Minimum number of measurements for evaluating Bertholletia excelsa.

“…Similar results have been reported on other perennial fruit plants that also expressed cyclic behavior, such as acerola (Lopes et al, 2001), guava (Degenhardt et al, 2002), araçazeiro and pitangeira (Danner et al, 2010), peach (Bruna et al, 2012), sweet orange (Negreiros et al, 2014), and banana , in which the methodology based on principal components provided the highest estimates of r and R. Pedrozo et al (2015) estimated repeatability coefficients based on two-trait mixed models of Brazil nut production in Roraima. The number of fruits per plant and the fresh weight of seeds were evaluated in two native forest populations, for 5 and 8 consecutive years, in 51 and 85 adult trees, respectively.…”

“…The repeatability coefficient in the Brazil nut was estimated by Pedrozo et al (2015) and Assis (2016) from the methodology of mixed models. However, there is still little research that evaluates the number of measurements needed to select superior genotypes of the Brazil nut, using multivariate techniques.…”