Canopy architecture - optimizing the interface between fruit physiology, precision crop management, and mechanical/robotic efficiencies

Precision orchard management strategies have evolved over decades of research with the goals of improving production efficiency, yield, and fruit quality. The integration of promising technological efficiencies (sensors, mechanization, and robotics) with orchard systems is dependent on horticultural manipulation of fruit tree canopy architecture and natural growth traits. We have demonstrated how a simplified canopy structure and uniform fruiting units facilitate more precise quantification of cropping and growth, i.e., crop load estimation and management, as well as improve the potential for successful adoption of sensing and mechanization technologies. Since 1999, we have developed and refined two-dimensional (planar), simplified canopy architectures for spur-bearing fruit trees like sweet cherry and plum, ultimately leading to the upright fruiting offshoots (UFO) training system that was prescient in its adaptability to recent developments in mechanization, automation, and robotics. Initially conceived for improving precision management of leaf area-to-fruit ratios on dwarfing precocious sweet cherry rootstocks, the UFO architecture optimally facilitates the sensing and quantification of light-exposed leaves (the most important photosynthetic sources) and readily accessible fruits (the strongest photosynthetic sinks) that are critical to precision orchard management technologies. The multiple vertical leaders of the UFO planar canopy architecture utilize the naturally acrotonic, apically-dominant growth habit of most fruit trees, resulting in efficient training and light interception, unparalleled uniformity in fruit development and ripening, and significant improvements in labor efficiency. The ability to diffuse vigor and reduce acrotony through multiple leaders permits a wide range of rootstocks to be utilized successfully, unlike most training systems. Ten years of production research at multiple sites across North America have compared UFO sweet cherry canopies with spindle, bush, and super spindle tree structures across rootstocks and cultivars. The results reveal significant advantages for yields, orchard management efficiencies, and adaptation to mechanization of orchard tasks that could even include robotics.