Abstract
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.
Highlights
The Brazil nut tree (Bertholletia excelsa HBK) occurs in about 325 million hectares of Amazon forests from Venezuela, Colombia, Peru, Bolivia, Guyanas and Brazil
Despite the low r estimates obtained in the present study, the accuracy estimates (Acm) associated with this parameter were high in all trait x population combinations evaluated, leading to the rm of approximately 0.80 and 0.70 for ITA e Cujubim region (CUJ), respectively
The average yield of Brazil nut seeds obtained in the ITA population was lower than that obtained in a study conducted at the Chico Mendes Extractive Reserve (RESEX) in Acre (WADT et al, 2005) and similar to that obtained at São João da Baliza in Roraima (TONINI et al, 2008)
Summary
The Brazil nut tree (Bertholletia excelsa HBK) occurs in about 325 million hectares of Amazon forests from Venezuela, Colombia, Peru, Bolivia, Guyanas and Brazil. The Brazil nut chain has great ecological, social and economic value for the Amazon region, creating jobs and income for thousands of the region’s rural and urban workers (CLAY, 1997; TONINI, 2011). The nut kernel is known in the market for its high nutritional value, as it is rich in lipids, proteins, fibers, vitamins, and minerals, and especially selenium (CARDARELLI; OLIVEIRA, 2000; GONÇALVES et al, 2002; SOUZA; MENEZES, 2004). This last element has antioxidant activity and is, recommended in the prevention of cancer and cardiovascular diseases
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