Light Transmission, Yield Distribution, and Fruit Quality in Six Tree Canopy Forms of 'Granny Smith' Apple

Six different orchard canopy forms with 'Granny Smith' apple (Malus domestica Borkh) were evaluated for yield and fruit quality attributes over three years. The canopies studies were young, established, and top-dominant central-leader, vertical axis, multi-leader, and tiered trellis planted in either N-S or E-W rows. Mean fruit weight, soluble solids concentration, and specific leaf weight were all positively related to light transmission within a canopy and, for each factor, a common linear regression described all canopy forms. The greatest proportions of total fruit yield occurred in those canopy regions with the highest light transmission values. Greenest and firmest fruit occurred in inner canopy regions, whereas red blush development on the skin surface occurred wherever light transmission exceeded 40% of above-canopy values. Quadrant position had little influence on fruit quality factors, but mean fruit size was greater on the north than on the south side of each canopy.