Training systems for sweet cherry: light relations, fruit yield and quality

Semi-dwarfing rootstocks have enabled the adoption of high-density orchard systems for sweet cherry. Understanding the effects of training systems on light capture and fruit quality of lateral bearing cultivars early in tree/orchard establishment is lacking. The aim of this study was to investigate light interception and fruit quality over two seasons of 4-5 year-old 'Kordia' grafted to 'Krymsk 5' rootstock and trained to the 2D planar training systems of upright fruiting offshoot (UFO), super spindle axe (SSA), tall spindle axe (TSA), Bibaum (BB) and steep leader (SL). Average light interception over the two seasons was highest in UFO and SL (69%) followed by BB (66%). Average yield was highest for SSA (15.1 t ha^-1) followed by SL (14.5 t ha^-1) and UFO (12.7 t ha). There were negative correlations between crop load and fruit dry matter content (r² = 0.67 and 0.84) and total soluble solids (0.92 and 0.42) in 2019-2020 and 2020-2021, respectively. Our results indicate that sufficient space is required between uprights for lateral bearing cultivars when trained to a planar training system to achieve optimal light interception and fruit quality. This study provides improved understanding to enable the adoption of planar training systems for lateral fruiting cherry cultivars at high-density plantings.