Analysis of growth and physicochemical changes in apple cv. Anna in a high-altitude tropical climate Análisis de crecimiento y cambios fisicoquímicos del fruto de manzana cv. Anna en clima de trópico alto

The objective of this research was to carry out an analysis of growth and physicochemical changes in cv. Anna apple in the Colombian high-altitude tropics using on the accumulation of growing degree days (GDD). Fruit samplings were taken every 15 days after anthesis (DAA) until harvest at 100 DAA (892.37 GDD). The dry and fresh weight and the equatorial and polar diameters followed a simple sigmoidal pattern. This was confirmed with the behavior of the growth rates. The equatorial and polar diameters increased drastically between 455.39 and 589.32 GDD (45 and 60 DAA), while the weight did not, indicating that the void spaces increased in the pulp during this period. The respiratory rate had the highest value (61.93±6.79 mg CO2 kg-1 h-1) at 159.61 GDD (15 DAA) and then decreased continuously until harvest. The firmness increased from 159.61 to 455.39 GDD and, then continuously decreased, at harvest, it was 38.38±3.48 N. The total soluble solids increased and had an ending value of 8.58±0.37oBrix. The total titratable acidity increased from 159.61 to 319.79 GDD (30 DAA), and then decreased until the end of the study with an acidity of 0.71±0.03%. The color index increased linearly as a function of development, but the values were <0 at harvest. These results are an important advance for knowledge on the behavior of apple cv. Anna under high-altitude tropical conditions. Additional key words: development; maturation; sigmoid growth; cell expansion; Malus domestica Borkh. 1 Universidad Pedagógica y Tecnológica de Colombia, Programa de Maestría en Fisiología Vegetal, Tunja (Colombia). ORCID Cepeda M. , A. : 0000-0002-0675-1601 2 Universidad Nacional de Colombia, Facultad de Ingeniería, Departamento de Ingeniería Civil y Agrícola, Bogota (Colombia). ORCID Vélez-Sánchez, J.E. : 0000-0002-1361-8374 3 Universidad Nacional de Colombia, Facultad Ciencias Agrarias, Departamento de Agronomía, Bogota (Colombia). ORCID Balaguera-López, H.E. :0000-0003-3133-0355 4 Autor para correspondencia. hebalagueral@unal.edu. co Doi: https://doi.org/10.17584/rcch.2021v15i2. 12508 REVISTA COLOMBIANA DE CIENCIAS HORTÍCOLAS Vol. 15 No. 2, e12508, May-August 2021 e-ISSN: 2422-3719 · ISSN-L: 2011-2173 Apples have high economic and nutritional value and are grown in many countries. The Department of Boyaca is important in the exploitation of deciduous crops in Colombia, including apples, japanese plums, peaches and pears, mainly because of the edaphoclimatic conditions of this department (Puentes et al., 2008; Orduz-Rios et al., 2020; Casierra-Posada et al., 2017). However, domestic apple production is well below national demand, resulting in large import volumes of apples from Chile. According to Puentes et al. (2008), the fundamental cause of problems in deciduous fruit trees in Colombia lies in the lack of cultivation planning. Mainly because the development of these fruit trees in the tropics is affected by the absence of chilling temperatures and long days (Fischer, 2013). However, there have been important advances in the use of new varieties with low chilling requirements and easy acclimatization to high-altitude tropics. Therefore, the study of deciduous fruit trees under tropical conditions is important for understanding the behavior of established varieties production factors that are necessary for each location to achieve good crop management (Puentes et al., 2008). The most important apple variety in Colombia is Anna. It requires 300-400 chilling hours. The epidermis has red stripes where it receives sunlight and a yellow color on the other side. The pulp is creamy white with a medium texture and a sweet acid flavor. The fruit is medium-sized and has an elongated shape. In Colombia, two harvests are possible in areas with a bimodal precipitation regimen (Campos, 2013). However, there are few studies for this variety. The growth and development of fruits are processes with biological and commercial importance (Malladi, 2020) that, must be modeled to design management strategies for apple orchards (Hester and Cacho, 2003). However, there are no recent scientific reports on the growth and development of apples in Colombia. This information would provide objective management recommendations for pruning, fruit thinning, fertilization, irrigation, harvesting, and other factors. One of the few studies available was conducted by Casierra-Posada et al. (2003), who reported results of a basic analysis of the growth of apples cv. Anna under the climatic conditions of Paipa, Boyaca by determining the weight and diameter of fruits and concluding that this fruit has a simple sigmoid growth curve. Likewise, Atay et al. (2010) reported that the growth of apples in temperate zones also follows a simple sigmoid pattern. However, Magein (1989) found that the growth of apples follows a double sigmoid curve, with a slow growth phase, attributed more to changes in the physiology of trees than to the physiology of fruits. In the world, new apple cultivars have RESUMEN El objetivo fue realizar el análisis de crecimiento y de los cambios fisicoquímicos del fruto de manzana cv. Anna en trópico alto colombiano en función de la acumulación de grados día de crecimiento (GDC). Se hicieron muestreos de frutos cada 15 días después de antesis (DDA) y hasta la cosecha a los 100 días (892,37 GDC). El peso fresco y seco y el diámetro ecuatorial y polar siguieron un patrón sigmoide simple, esto se corroboró con el comportamiento de las tasas de crecimiento. El diámetro ecuatorial y polar aumentaron drásticamente entre los 455,39 y 589,32 GDC (45 y 60 dda), mientras que las masas no, indicando que en este periodo se incrementan los espacios vacíos en la pulpa. La tasa respiratoria tuvo el mayor valor (61.93±6.79 mg CO2 kg-1 h-1) a los 159,61 GDC (15 DDA) y luego disminuyó de forma continua hasta la cosecha. La firmeza aumentó de los 159,61 GDC a los 455,39 GDC, luego fue decreciendo continuamente y en la cosecha fue de 38.38±3.48 N. Los sólidos solubles totales incrementaron y al final presentaron un valor de 8,58±0,37oBrix. La acidez total titulable incrementó de los 159,61 GDC a los 319,79 GDC (30 DDA), para luego disminuir hasta el final del estudio, momento en el que presentó una acidez de 0.71±0.03%. El índice de color aumentó de forma lineal en función del desarrollo, pero en la cosecha los valores fueron <0. Estos resultados son un avance importante hacia el conocimiento del comportamiento del fruto de manzana cv Anna en condiciones tropicales. Palabras clave adicionales: desarrollo; maduración; crecimiento sigmoide; expansión celular; Malus domestica Borkh. Received: 22-02-2021 Accepted: 28-02-2021 Published: 21-03-202