Articles in press

Previous issues

Orchard cooling with overtree sprinkler irrigation to improve fruit colour and quality of 'Topred Delicious' apples

Download paper Ver Versión Española

Authors: I. Iglesias, J. Graell, G. Echevarría, M. Vendrell
Issue: 95V-3 (267-288)
Topic: Plant Production
Keywords: apple, fruit, cooling, sprinkler irrigation, colour, anthocyanin, fruit quality

The influence of evaporative cooling irrigation by sprinkler irrigation on fruit colour of 'Topred Delicious' apples (Malus domestica Borkh.) was evaluated in the area of Lérida (NE Spain) over a two‑year period. Cooling irrigation was applied daily for two hours for 25 to 30 days preceding harvest date. Three cooling treatments were evaluated: sprinkler irrigation applied at sunrise, at midday and at sundown, with a control without sprinkler irrigation. Colour measurements were made with a tristimulus colorimeter using the CIE [1976] L*a*b* system, providing an objective determination of two main visual attributes of colour: Lightness and Hue. Fruit colour was affected by the cooling irrigation and also by the weather conditions of the particular year. Improvement of colour in cooled fruits. especially when the sprinkler irrigation was applied at sunrise and at sundown, was followed by better chromaticity values of CIELab tristimulus space and higher anthocyan in content. Variations in fruit color from year to year can be attributed to seasonal environmental differences: the minimum temperatures, due to the current season or to the cooling irrigation, had a direct effect on fruit color, and consequently the season factor and also its interaction with the sampling dates were significant. The interaction treatment x sampling dates was also significant. In 1993 lower temperatures prior to commercial harvest provided better fruit color in all treatments in comparison to 1994 in which average temperatures were warm. Al commercial harvest, a linear regression for all seasons of anthocyanin content on the ratio of L, a*/b* and Hue provided and R2 = 0.80, 0.79 and 0.78, respectively. These relationships alow to use the colorimeter for rapid, non destructive estimation of fruit anthocyanin content. The minimum temperatures, due to the current season in 1993 had a direct effect on fruit colour, and consequently the climatic factor has a significant interaction with this parameter. Fruit weight, in 1994, firmness and soluble solids concentrations were significantly higher in cooled fruits than the control, whereas titratable acidity was not influenced consistently by the evaporative cooling.

Back to Issue 95V-3


 -   -   -   -   -   -   -