Spectral Measurements on 'Elstar' Apples during Fruit Development on the Tree

The portable spectrophotometer worked reliably and indicated sensitively changes of the spectral signature of apple fruit during the measuring period. Spectral indices as well as laboratory data demonstrated very high variance of maturity progress between individual 'Elstar' fruits. The spectral indices of each single fruit changed continuously over the time. The red-edge as well as a normalised chlorophyll index exhibited moderate decline, while a normalised anthocyanin index increased sigmoidally. The results obtained with these indices showed the potential of non-destructive fruit maturity monitoring on the tree.