Performance of Satsuma Mandarin within Various Orchard Designs
Type of Degreethesis
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Freeze protection is the most challenging aspect of commercial satsuma mandarin production in Alabama. In addition to other freeze protection methods, satsuma growers have used various orchard designs to reduce freeze damage for decades. These designs include interplanting between pecan and pine trees, and planting behind windbreaks. The goal of the first experiment was to determine the effect of different orchard designs on canopy temperature, freeze damage, fruit quality, and yield. All treatments reduced the amount of freeze damage suffered compared to the full sun orchard (control). Interplanting satsuma mandarin trees with mature pine trees resulted in warmer temperatures within the canopy. Fruit from shaded pine tree canopies had higher soluble solids content and reduced fruit weight. Heavy shading resulted in lower yields for the dense pine tree canopy treatment in 2009, when no damaging freeze occurred. Compared to other orchard designs, satsuma mandarin trees planted under pine tree canopies had greater percentages of their expected yield in 2010, when a severe freeze did occur. Dense pine tree canopies can provide an insulating effect that reduces leaf loss and subsequent yield losses when severe freezes occur, but potential maximum yields are reduced in non-freeze years compared to satsuma mandarins grown in full sun. The second study focused on the influence of different orchard designs on photosynthesis, leaf area, specific leaf area, and fruit quality. All shading treatments reduced photosynthesis. Heavy shading from dense pine tree canopy increased leaf area, specific leaf area, and reduced fruit size, and vitamin C content. There were no differences in soluble solid content (SSC) for satsuma fruit grown under dense pine tree canopy, however moderate pine tree shading increased SSC. Satsuma rind thickness was reduced with pine tree shading. There were no reductions in photosynthesis, fruit size, rind thickness, juice weight, or volume for satsuma fruit grown behind a windbreak. In years when severe temperatures are not an issue, yield may be reduced under pine tree canopies. However, shading only negatively affected fruit size and photosynthesis.