‘Delicious’ Apple Fruit Size and Quality as Influenced by Radiant Flux Density in the Immediate Growing Environment1

Fruits of ‘Delicious’ apple ( Malus domestica Borkh.) were grown under differing radiant flux densities (rfd nm) from 45 days post-bloom until harvest. The rfd nm affected red fruit color, soluble solids, starch content and size, but not firmness, pH or total acidity at harvest or after 105 days of storage at −0.5°C. Levels of rfd nm sufficient to enhance red color development in red sports of ‘Delicious’ were not necessarily sufficient to insure flesh quality.