Renewal Pruning Alone or in Combination with Thinning Pruning Affects Growth, Fruit Yield and Fruit Quality of Aroniaberry

Abstract

Aroniaberry (Aronia mitschurinii) produces small pome fruits that possess health promoting compounds. Management practices for orchards are lacking, since aroniaberry is a relatively new crop. Pruning is an important cultural practice to optimize fruit yield in orchards. The response of an established aroniaberry orchard to pruning was evaluated over three years (2020 to 2022). Pruning treatments were as follows: 1) renewal pruning (removal of shoots to the base) only in year 1; 2) renewal pruning in year 1 + thinning to 18 shoots in year 2; 3) renewal pruning in year 1 + thinning to 9 shoots in year 2; and 4) no-pruning (control). In response to renewal pruning, plants grew uniformly and vigorously, producing 28 new vegetative primary shoots with an average length of 66 cm by the end of the first growing season. Limited flowering and fruiting occurred in the second season for plants receiving pruning treatments. Fruit yield on pruned plants was significantly less than for unpruned controls. In season 2, increased thinning of renewal-pruned plants negatively affected the number of inflorescences per plant, but positively affected individual fruit fresh weight and fruit °Brix:titratable acidity ratios. Fruits from all treatments had similar monomeric anthocyanins, total phenolics and mineral content. In season 3, flower production and predicted fruit yield from pruned plants and unpruned controls were similar, even though pruned plants were substantially smaller. In the third season, there were no longer any differences between renewed + thinned plants and those that received only renewal pruning, making shoot thinning an unnecessary practice. The results of this study demonstrate that renewal pruning can be an effective way to manage and rejuvenate an aging aroniaberry orchard.