Innovative plant models for sour cherry production

PHOTO 1 - Overview of the experimental cherry orchard in full bloom

The traditional production of sour cherries in the Modena (Italy) area has strong and recognised identity and territorial characteristics and a local market that is already very receptive, with good prospects for expansion. 

In particular, "Amarene Brusche di Modena" PGI cherries are still a niche product, but the health and nutritional properties of sour cherries that research has now confirmed and the many transformations to which sour cherries lend themselves offer opportunities for growing commercial success and open up paths of innovation in both process and product. 

Cultivation, today mainly conducted according to extensive processes, can benefit from an evolution towards more efficient and sustainable innovative systems that allow high productivity, reduced production costs and the maintenance or enhancement of fruit quality.

With this aim in mind, the University of Modena and Reggio Emilia has evaluated the effects of innovative cultivation models in terms of varieties, planting distances, pruning management and defence against biotic and abiotic adversities in the Work Package 'New genotypes and planting models for an integrated and sustainable production' of the FAR Mission Oriented multidisciplinary research project 'Process and product innovations in the black cherry sector: an integrated approach for the valorisation of a typical Modenese production', financed by the Fondazione Cassa di Risparmio di Modena and coordinated by Prof. F. Licciardello. F. Licciardello of Unimore.

The "pedestrian" orchard

The trials were conducted in an experimental 'pedestrian' cherry orchard with plots at different densities of plants per hectare (1250 - medium-high density- MHD; 1666 - high density- HD; 2500 - very high density- VHD) set up in 2015 at the Piombini company, in Casinalbo di Formigine (Modena, Italy). 

During the two-year period 2021-2022, vegetative growth, fruit productivity and quality, harvesting and pruning times for manual and mechanical production of Amarena del Rio were analysed. This is a new variety that, due to the size and quality characteristics of the fruit, can be considered dual-purpose, for fresh consumption as well as for processing.

PhOTO 2 – Del Rio sour cherries

Results

The two-year surveys showed that, with the same distance between rows (4 m), the reduction in the distance between plants on the row from 2 m to 1 m, and the consequent increase in the density of plants per hectare, resulted in lower vegetative growth, due to competition between root systems and canopy lighting conditions. In both years, production per tree decreased as plant density increased, with averages over the two years of 10 kg/plant for MHD, 7.8 for HD and 5.6 for VHD, respectively, and production yield per hectare increased from 12 t to 14 t from a density of 1250 to 2500 plants per hectare. 

The vegetative growth and production trends over the two-year period show that the cherry orchard can maintain good productive efficiency and stability over the years and a condition of vegetative-productive balance even at the highest density.

PHOTO 3 - Production per plant in 2022 at the three planting densities

The quality characteristics of the fruit (size, sugar content, acidity, firmness) were also satisfactory at all the planting densities and pruning forms applied. In particular, in both years the trees at a density of 2,500 plants/hectare produced more drupes of high size, with calibre greater than or equal to 22-24 mm. This positive result is largely attributable to the cultivar used, which combines good productivity characteristics with a compact vegetative habitus and average vigour.

PICTURE 4 - Distribution in the different size classes of the fruit obtained at the three different planting densities.

Mechanical pruning with manual trimming carried out in the winter of 2021 reduced labour time compared to entirely manual pruning, but the growth response of the foliage made it necessary to intervene with manual pruning in 2022, making it necessary to adopt dynamic pruning systems in high-density plantations, with alternating manual and mechanical pruning over the years.

Figure 5 - Mechanised winter pruning of sour cherries

The Keep in Touch® multifunctional netting cover set up in the very high density planting resulted in a production, as an average over the two-year period, not significantly different from that of the open-air planting and made it possible to avoid Drosophila suzukii defence interventions and to improve some quality aspects of the sour cherries.

Cristina Bignami
DSV - UNIMORE

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