OPTIMIZING ORANGE GROVE FACTORS FOR FRUIT PRODUCTION AND HARVESTING

Ten hectares of oranges were planted in 1980 in an experiment to investigate optimal management practices for different tree spacings, scion, and rootstock combinations. Experimental factors included two between-row spacings (6.0, 4.5 m), two in-row spacings (4.5, 2.5 m), two scions ('Hamlin', early season; 'Valencia', late season), two rootstocks (Milam, vigorous; Rusk citrange, moderately vigorous), and two tree heights (3.7, 5.5 m). Conventional equipment and practices were used to provide grove care and fruit harvesting. A 2-m middle or alleyway was maintained between rows for production and harvesting equipment traffic. The oranges were manually harvested for processing using conventional fruit handling equipment. During the 1980s, trees in the experiment endured several severe freezes which markedly reduced Florida citrus production. After nine fruit producing seasons, cumulative fruit and soluble solids yields were superior for the early orange, moderately vigorous rootstock, 6.0 x 2.5 m spacing and 5.5 height. Trees on this moderately vigorous rootstock developed smaller canopies with greater quantities of fruit per unit canopy volume. The smaller canopies allowed for a higher percentage of fruit to be harvested without a ladder, and more space for movement of pickers and fruit handling equipment. They also provided fruiting conditions which favored the use of picking aids or platforms and the use of shakers and robots.