A Statistical Approach for Assessing the Heterogeneity of Hass Avocados Subjected to Different Postharvest Abiotic Stresses

Abstract

C. Fuentealba, R. Pedreschi, I. Hernández, and J. Saavedra. 2016. A statistical approach for assessing the heterogeneity of Hass avocados subjected to different postharvest abiotic stresses. Cien. Inv. Agr. 43(3):356-365. Hass avocado (Persea americana Mill.) is marketed worldwide. Due to its complex physiology, a wide variability in postharvest ripening can be observed, i.e., heterogeneity in the number of days to reach edible ripeness. There is a need for a simple and objective method for evaluating the efficacy of postharvest treatments in the reduction of this postharvest ripening heterogeneity given the high demand of import countries for consistent quality and product homogeneity. Therefore, the aim of this study was to compare the appropriateness of different statistical methods used to evaluate this ripening heterogeneity. Bartlett's, Cochran's, Levene's homogeneity of variance tests were applied to different treatments. In addition, a multiple comparisons test of squared residuals (parametric and non-parametric) was applied. The classical statistical approaches (Bartlett's, Cochran's and Levene's tests) showed similar results as the multiple comparisons test of squared residuals only when one treatment and large sample sizes (n=100) were evaluated. All statistical methods were able to detect significant differences in ripening heterogeneity from growers and storage conditions. The multiple comparisons test of squared residuals was the most suitable method for multifactorial experiments and small sample sizes (n=30) compared to the classical approaches, which increased the probability of obtaining false positives or a type I error.

Assessment of avocado textural changes during ripening by using contactless air-coupled ultrasound

“…This fact confirms that, although the pieces belong to the same batch, the great heterogeneity among the avocado fruits purchased leads to different patterns in the textural changes. The highly heterogeneous nature of the avocado hardness represents a relevant handicap for the fruit logistics and retail companies, leading to unreliability in terms of the ripeness of the fruit delivered to the consumers , given the high product demand in the ready-ripe stage (Blakey, Bower and Bertling, 2009;Fuentealba et al, 2016).…”

Influencia de la Materia Seca como Índice de Madurez de Cosecha y Tiempo de Almacenamiento en Frío sobre la Calidad del Aguacate cv. Hass Producido en la Región del Trópico Alto

“…En este cuadro se pueden observar diferencias estadísticamente significativas (p<0,05) en la mayoría de las coordenadas de color, tanto para IM, como TA en las fincas EB, BV y LE. La variabilidad del color por finca están ligadas a las zonas de cultivo y condiciones pre cosecha, indicando que es importante en planta postcosecha agrupar por IM y características de cultivo similares, para disminuir la heterogeneidad del color durante la maduración de los frutos (Fuentealba et al, 2017). La coordenada de croma a* mostró valores positivos bajos (0,43 a 7,0) para todas las fincas, esto corresponde a un color rojo tenue o púrpura en todos los frutos, Según, Cox et al, (2004), el ambiente en el cual los frutos crecen y son cultivados, ocasiona que en la maduración pase a una coloración purpura o directamente negra en la cascara del aguacate a madurez de consumo.…”

Indirect selection of maize genotypes based on associations between root agronomic and anatomical characters

“…The assumptions of the ANOVA (Cruz et al, 2012) were verified with studies of multicollinearity between all the evaluated characters, homogeneity of variance by Cochran's and Bartlett's tests (Fuentealba et al, 2016), and normality by the Lilliefors test (Razali and Wah, 2011). For characters that did not fulfill some of the assumptions, data were transformed (Cruz et al, 2012); lodging (Lod) was transformed to √(x)+1 and MeA to Log(x)+1.…”