Phenology of hass avocado in the Andean tropics of Caldas, Colombia

Abstract

The objective of this study was to document and analyze the effect of climate on the phenological development of ‘Hass’ avocado in two contrasting zones of the Andean tropics of Caldas, located at altitudes of 1,950m and 2,400m a.s.l., respectively. A completely randomized experimental design was carried out using a five to seven year-old ‘Hass’ tree as experimental unit and 15 replicates on each area. Observations were conducted on lateral sylleptic shoots and their corresponding apical buds located on the eastern and western sides of each tree. The destination of the apical bud of lateral shoots was quantified, floral phenology was documented, heat units were calculated from reproductive bud stage 1 to anthesis and to harvest and root growth was followed for each study area. Air temperature, soil temperature, precipitation and photosynthetically active radiation (PAR) values were recorded over time. Differences were found in the number of apical buds of lateral shoots with reproductive and vegetative destination, flowering phenology, heat units, root growth, PAR and precipitation. Differences were found among variables evaluated at the two contrasting altitudes. There is a clear need for further ecophysiological studies on this fruit tree in tropical areas in particular.

Phenological variations of avocado cv. Hass and their relationship with thermal time under tropical conditions

“…The base temperature found in the present study, according to the different models for the entire cycle, fluctuated between 5.4 and 6.3 °C, with an average of 5.86 °C. This result contrasts with that reported by several authors, who mention that the base temperature for Hass avocado is 10 °C [ 13 ]. This is possibly due to the fact that, under tropical conditions in high Andean zones where Hass avocado is produced, periods of temperature below 10 °C are infrequent and last for very short periods, allowing the plant to grow below this threshold without affecting its development and productivity.…”

“…Regarding the determination of the base temperature, the values were quite different from those reported in the literature and generalized by decision-makers, who use a value of 10 °C, independently of the area and the specific climatic conditions in the equatorial region [ 13 ]. Meanwhile, the values obtained in our work ranged between 0.3 and 7.5 °C, depending on the different phenological stages evaluated, indicating that cv.…”

“…The objective was to determine variation among the used methods, highlighting as the main objective the calculation of the TB for tropical conditions. It is important to mention that normally, BT is a parameter arbitrarily assumed as 10 °C as is reported in previous analysis [ 13 ], and calculated originally under latitudes other than tropical [ 34 ]. This approach does not consider that TB is a function of multiple environmental variables, especially in tropical conditions where elevation presents a substantial influence on the average temperature of the fields [ 14 , 23 ].…”

“…The high edaphic and climatic variability under Colombia avocado production zones provides a range of microclimates, influencing growth patterns and fruit production indicating the necessitated an in-depth understanding of the crop's responses [ 11 , 12 ]. Phenological and physiological investigations have focused on the crop's responses to climatic stressors, such as water availability and temperature fluctuations [ 11 , 13 , 14 ]. These studies have facilitated the development of strategies to mitigate potential yield losses due to adverse environmental conditions.…”

Spectral Characterization of Avocado Persea Americana Mill. Cv. Hass Using Spectrometry and Imagery from the Visible to Near-Infrared Range

“…Avocado plants can present different phenological stages simultaneously, including vegetative growth, flowering, and fruit production [28]. This condition causes natural changes in the spectral response of the plant, even without being subjected to biotic or abiotic stress.…”