ASHS 2025 Conference

Development of control measures for nutrient-related apple fruit disorders like bitter pit requires a better understanding of calcium metabolism in the tree. Limiting this understanding is a rapid and accurate method for measuring the concentration of calcium in various plant organs including the leaves. Optimally, measuring calcium levels could be done at the single leaf level, or better yet for whole leaves at a resolution of sub-millimeter dimensions. We report on the use of X-ray fluorescence for apple leaf tissue to quantitatively measure leaf calcium tissue. Using 7-mm diameter discs taken from Granny Smith apple leaves mid-season, we were able to demonstrate that the emission data from a scanning Bruker X-ray fluorescence instrument could be easily transformed to predict accurate and precise calcium levels in apple leaf tissue. If similar relationships can be determined for other minerals, this type of analysis will enable the quantitation of multiple minerals within minutes. Provided software analysis of the samples can be automated, the turn-around time for tissue analysis would be on the order of one or two hours for hundreds of samples