Repeatability and minimum number of measurements for bacabi palm (Oenocarpus mapora) racemes characters

Abstract

Bacabi (Oenocarpus mapora H. Karsten) is a native Amazonian palm that produces racemes with hundreds of fruits with great potential for commercial and food uses, but has not been well studied. The objectives of this research were to estimate the repeatability coefficients, to determine predictability and the number of measurements needed for raceme characters of this palm. Twenty seven individuals of bacabi that belong to the Germplasm Bank of Oenocarpus/Jessenia at Embrapa Eastern Amazon, in Belém, PA, Brazil were evaluated. Three fully matured racemes from each plant were sampled to measure six characters: raceme total weight (RTW) and fruit weight per raceme (FWR), number of rachillae per raceme (NRR), rachis length per raceme (RLR), weight of 100 fruits (WHF) and fruit yield per raceme (FER). The repeatability estimates were obtained by three statistical methods: analysis of variance; principal components; and structural analysis. For all characters, the estimates of the repeatability coefficients presented values with very similar magnitudes in the three methods. The estimates of repeatability coefficients and determination coefficients were relatively high (r > 0.60 and R2 > 81.7%) for the characters FER and NRR, showing regularity of genotypes for these raceme measurements. For these characters, the minimum number of racemes necessary to estimate the true character value of the genotypes was thirteen (FER) and five (NRR), with 95% reliability. The remaining characters showed repeatability and determination coefficients with medium to low values, indicating the need for better environmental control to make the measurements.