A Model for Predicting Diameter of 'Red Sensation' Pears

Abstract

The pear cultivar 'Red Sensation' is showing popularity in the industry, because of its highly-colored, sweet and juicy fruit. Fruit size is critical for marketing pear; therefore, knowledge of growth dynamics becomes essential to program harvesting with minimum losses of size and flavor. The objective of this work was to develop a model to predict the seasonal growth for 'Red Sensation' pears, expressed in terms of fruit diameter as a function of time from full bloom. Fruit growth was followed at the Experimental Farm of the Universidad Nacional del Comahue, High Valley region, Río Negro, Argentina (38°56'S; 67°59'W), located in an arid region, with average annual rainfall of 250 mm, on a sandy loam soil, during the 2005-06, 2006-07, 2008-09, 2009-10 and 2010-11 growing seasons. The orchard was irrigated by surface flooding, and cultural practices were performed according to the local standard program. Trees were selected at random, and maximum fruit diameter (FD) measurements were carried out every two weeks with a Vernier caliper. The range of sampling dates was 19 and 117 days after full bloom (DFB). Equations were developed with SYSTAT procedure. The R 2 values and residual mean squares were used to evaluate the goodness-to-fit of the models. Results showed that the following logistic model provided the most satisfactory fit to the pooled data (n=695), as compared to the power and linear equations: FD (mm)= 81.49/(1 + e 1.9865-0.0301 DFB ), R 2 =0.92, P<0.001. Fruit maximal absolute growth rate, derived from the selected function, was 0.61 mm/day. A prediction chart was based on the development of the equation and showed 'Red Sensation' pear sizes, at various times after 112 DFB, with practical application to aid crop marketing. This model can also be used for planning orchard practices such as thinning and irrigation.

Effect of Regulated Deficit Irrigation (RDI) on the Growth and Development of Pear Fruit (Pyrus communis L.), var. Triunfo de Viena

“…Similar to the diameter growth in fruits of the 'Red Sensation' pear tree [38] and in fruits of Asian pear trees [39], the equatorial diameter growth of the fruit in the present study during the two years showed a behavior adjusted to a sigmoid logistic model, defined in three phases. In the first phase, cell division occurred from flowering up to 49 and 50 days after flowering (DAF) in 2014 and 2015, respectively, with rapid growth.…”

“…The third phase, in which maturation was reached, was characterized by a continuous increase in diameter from 113 and 114 DAF until harvest (169 and 161 DAF) for 2014 and 2015, respectively (Figure 1A,B), which concurred with reports for pear [37] and apricot [40] plantations. Similarly, Garriz et al [38] found that the maximum value for the AGR of the fruit was 0.61 mm day −1 . In addition, those authors determined three phases of growth in the diameter of the fruits, whose growth curve had a sigmoid shape.…”