Abstract

PARRA-CORONADO, Alfonso; FISCHER, Gerhard  and  CHAVES-CORDOBA, Bernardo. Thermal Time for Reproductive Phenological Stages of Pineapple Guava (Acca sellowiana (O. Berg) Burret). Acta biol.Colomb. [online]. 2015, vol.20, n.1, pp.163-173. ISSN 0120-548X.  https://doi.org/10.15446/abc.v20n1.43390.

Crop development of feijoa (Acca sellowiana (O. Berg) Burret) is mainly stimulated by temperature, but is also affected by other climatic factors. The determination of the development in terms of thermal time or growing degree days (GDD) is more precise than calendar days. The aim of this study was to propose a phenological model for feijoa cv. Quimba, in which the base temperature (Tb) for four different phenological stages and its duration in terms of GDD is estimated to predict the timing of anthesis, fruit setting and harvesting. During the years 2012 to 2014, in two localities of the department of Cundinamarca, Colombia, twenty trees per farm were labeled, dates of occurrence of phenological stages, starting from floral button were recorded. Tb was estimated using the method of minimum coefficient of variation, as well as duration of the four reproductive phenological stages in terms of GDD. The results showed that Tb and GDD vary depending on the stage of development of the crop; in general, an average of 2651 GDD and 189 days is required to reach the flower bud to the fruit harvest. The parameters of the regression analysis showed that the model successfully predicted phenological stages when estimated Tb for each of them was used, with high determination coefficient. Cross-validation showed good statistical fit between predicted and observed values; intercept was not significantly different from zero (p <0.05) and the slope was statistically equal to one.

Keywords : base temperature; development; growing degree days; phenology model.

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