Evaluating Maturity Index IAD for Storability Potential in Mid-Season and Late-Season Apple Cultivars in the Light of Climate Change

Reducing food losses in apple production is becoming increasingly important, as the effects of climate change constitute a challenge to food production. Improving methods for determining fruit maturity at harvest leading to the longest storability is crucial, thereby facing more unpredictable seasonal weather conditions. In addition, the increasing temperature is affecting common maturity indices differently; thus, present practice may not be valid. In this study, a non-destructive, time-efficient method was used, tentatively indicating maturity. This study was performed during three climate-diverse years, reflecting more irregular climate conditions. Mid- to late-season cultivars 'Frida', 'Ingrid Marie', 'Rubinstar', and 'Elise' were harvested at different pre-determined I-AD (index of absorbance difference) intervals and stored for five months. Correlations between I-AD values at harvest and total losses after storage were found for all cultivars and years, while only a few correlations related to firmness after storage were found. Although a strong effect of year was related to correlations between I-AD and different quality parameters, no noticeably general differences could be found between the exceptionally warm year in comparison to the other investigated years. I-AD, as a maturity index, thus, seems to be resilient to changing temperatures and can be used as a complementary maturity index.