The Impact of Modern Orchard Architectures and Rootstocks on Production, Quality, and Mineral Nutrition of Fuji Apple
In spite of the huge potential and interest in evaluation of various rootstocks and various tree canopy architectures, there is no such a study in the Pacific Northwest region of the United States. Thus, we will study four different canopy architectures, called Tall Spindle, Vertical Axis, Tilted Wall (Y System) and Straight Wall. Two different orchards will be established for this project at the University of Idaho Pomology Program site. For the Tall Spindle and Vertical Axis study, Aztec Fuji trees on B.9 and RN.29 are being planted at 3 x 13 ft. spacing. For the Tilted Wall and Straight Wall architectural design, Aztec Fuji trees on B.9 rootstock are being planted at 3 x 12 or 6 ft x 12 ft spacing. Trees in both orchards will be irrigated with full drip irrigation and the volume of required water will be calculated based of the
evapotranspiration data. The experimental design in one of the orchards will be randomized complete block split plot with rootstocks (RN.29 and B.9) as main effect, canopy architecture (Tall Spindle and Vertical Axis) as sub-plot, each with 5 blocks of 20-tree plots. In the other orchard, Aztec Fuji on B.9 rootstock will be used in a randomized block design with Tilted Wall at 3 x 12, Tilted Wall at 6 x 12, and Straight Wall as treatments, each with three 10-tree blocks. Tall Spindle: Trees in tall spindle system will receive a minimum pruning at planting, and all side small branches (feathers) will remain for fruiting. In the second year, only two cuts will be made to eliminate large side branches, and thus will have a very low cost for pruning. Vertical Axis: Trees in this system are topped at 36-inch in height at planting and all side branches are removed to leave one or two buds.
Then, only four main branches will remain permanently. Straight Wall (upright wall): In this system, Aztec Fuji apple on B.9 are being planted straight at 3 x 12 or or 6 x 12 ft spacing and trees are supported by posts and wires and wires are installed at 18-inch spacing. Branches will be tied to the wire in both directions. Tilted Wall (Y system). In this system, trees are planted at a 30 degree angle (tilted) and branches arising from every 18 inches along the main trunk are tied to a wire, creating a total of 7 fruiting "lines" on each side. Tree growth, fruit yield, and leaf (and perhaps fruit) minerals will be measured annually. For leaf mineral analysis, 30 leaves per tree will be sampled randomly from several branches around the tree from the middle of the current-season's shoot in mid-August each year. Leaves will be washed and dried and ground and percent dry weight will be
calculated. Tissue nitrogen (N) will be determined using a LECO Protein/Nitrogen Analyzer, and potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), manganese (Mn), and copper (Cu) will be measured by dry ashing at 500 oC, digestion, and atomic absorption spectrophotometery. Thirty-four fruits from each tree will be picked randomly at commercial harvest time, and quality attributes at harvest and after storage will be determined. Analyses of variance will be conducted by using SAS software.