GOLDEN DELICIOUS APPLE FRUIT SHAPE AND RUSSETING ARE AFFECTED BY LIGHT CONDITIONS

The effect of light on apple fruit shape was studied by exposing 5-yea r-old potted apple trees cultivar 'Golden Delicious' Clone B in open a ir to six lighting regimes obtained by altering the natural daylight ( control) by means of Ultra-violet (UV)-Blue sunlamps and Red-Infra-Red (R-IR) lamps and/or by shading with corrugated fiberglass-polyester s heets to cut off UV-B and violet wavelengths. Shading increased the le ngth/diameter (L/D) ratio of the fruit and decreased the incidence of russeting. Natural light produced the lowest L/D ratio and greatest am ount of russeting. The Blue/UV-B ratio had no consistent effect on sha pe or russeting. The Red/Far-Red ratio did not vary greatly among trea tments and was not related to differences among fruit.