Sweet cherry rootstock evaluations in a sub-alpine environment

In recent decades, sweet cherry production in the Trentino region of northern Italy, has been of special interest for growers and the local cherry fruit industry. Although Trentino represents a small part of the total national cherry production, with a surface area of 250 ha, it plays a key role due to the harvest time and high fruit quality performance. Since the 1990s, cherry growers have adopted intensive planting systems, with tree densities of 1500-2500 plants per hectare, and the introduction of mid-late high-quality cultivars such as ‘Kordia’ grafted on the dwarfing rootstock GiSelA®5. Beside the well-known GiSelA®5, other clonal rootstocks that confer lesser or greater vigour are available to a limited extent. For this reason, it was decided to verify the vegetative and productive traits of various rootstock genotypes in three locations in the Alpine Arc, aware that particularly for cherries, rootstock behavior is influenced strongly by the environment. In 2015, ‘Kordia’ trees grafted on 14 different rootstocks (GiSelA® 3, 5, 6, 12, 13, and 318/17; Piku 1, 3, and 4; Krymsk® 5 and 6; Weiroot 720; and Weigi® 1 and 2) were planted in a randomized block design experiment. The sites are 1) Pergine Valsugana (Trentino), at 500 m a.s.l., 2) Berbenno (Sondrio) at an altitude of 340 m a.s.l., and 3) Aldino (South Tyrol), at an altitude of 1100 m a.s.l. Tree size, yield and qualitative fruit characteristics were collected every year and in 2018, 2019 and 2020, the mineral contents of the leaves were analyzed. This paper reports the results of the first eight years of cultivation, up to 2022, highlighting how significant differences emerged between the different rootstocks in terms of vigour, productivity, and fruit quality