Evaluation of SPAD Index for Estimating Nitrogen and Magnesium Contents in Three Blueberry Varieties (Vaccinium corymbosum L.) on the Andean Tropics

Abstract

In the Ericaceae family, blueberries are the most commercially important species. Estimating the nutritional and physiological status of plants is a common practice carried out by producers. However, conventional methods are destructive, costly and time consuming. In recent years, methodologies such as measurements with the SPAD chlorophyll index have become available, which has proven to be an easy, fast and non-destructive method for estimating chlorophyll, N and Mg contents in the field. Therefore, this research aimed to estimate variations in SPAD readings between varieties and to determine whether Chlorophyll Index (SPAD) values are associated with Nitrogen and Magnesium contents in blueberry plants (Vaccinium corymbosum L.) from the varieties ‘Biloxi’, ‘Legacy’ and ‘Victoria’ in the vegetative phase under the conditions in the municipality of Paipa-Boyacá (Colombia). The varieties presented statistical differences in the SPAD index values, with a linear correlation between the SPAD index and the contents of N and Mg with a coefficient of determination (R2) greater than 0.8 in the three varieties. This result confirmed the usefulness and importance of using SPAD as a nutrition management tool in the evaluated varieties based on the SPAD readings, with a subsequent relationship with the threshold values of the foliar N and Magnesium status under field conditions.