2018 ASHS Annual Conference

Trees account for the majority of expenses when establishing high-density plantings. The vast proportion of nursery trees are produced in the field and shipped bare-root. These trees are prone to transplant-shock and may require additional time to fill orchard space. The objectives of this project were to 1) compare two nursery production systems (air root-pruning containers and field-produced liners [i.e., bare-root trees]) on the growth and development of above-ground and below-ground organs of apple trees during the formative ‘nursery’ year and, 2) correlate these parameters with canopy growth and fruiting during the establishment years in the orchard. We hypothesized that container-produced trees would possess higher-quality root systems that mitigate transplant-shock and result in rapid canopy infill to expedite orchard return on investment.

This experiment was conducted in 2017 at the Michigan State University Horticulture Teaching and Research Center. Three apple cultivars ‘Gala’, ‘Fuji’, and ‘Honeycrisp’ were bench-grafted to M9 Nic29 rootstock and divided into two production systems: Ellepot containers and field liners. Entire plants were carefully harvested from each production system several times throughout the season. Leaf area, average leaf size, trunk cross-sectional and total above-ground dry matter were quantified. Whole root systems were scanned to determine root growth and architecture (size classes) then dried (dry matter). Growth of Ellepot-produced trees was more uniform and total leaf area, average leaf size, and seasonal above ground dry matter were significantly (P < 0.05) greater than field grown trees, irrespective of scion. Root morphology differed drastically between the two systems. Ellepot-produced trees had markedly higher fine root production and greater root length density compared to field liners. In spring 2018, container and bare-root trees were established in an orchard. Root and canopy development are being monitored throughout the season.