Identifying heatwave resilient genotype-rootstock combinations in pear orchards through integrated soil and physiological analyses

Italy leads the production of pears (Pyrus communis L.) in Europe, with Emilia-Romagna as the national hub; however, for some years the sector has been facing a severe decline due to rising cultivation costs, phytopathologies, and climate instability. Since 2018, the area occupied by pear orchards has shrunk from 18,300 to 10,500 hectares.  The strong prevalence of few traditional varieties (most notably the stress-susceptible Abbé Fétel) severely limits genetic diversity and adaptive capacity, underscoring the urgent need for diversified germplasm and optimized rootstock-scion combinations suited to specific pedoclimatic conditions.​
To diversify the pear tree germplasm cultivated in Emilia-Romagna, comparative research focused on rootstock–genotype combinations was undertaken. This in-field study specifically aims to identify the most heatwave-resistant genotype-rootstock combinations in an experimental orchard located in the Po River Plain near Ferrara. Twenty pear genotypes (including reference cultivars Abbé Fétel and Williams), grafted on seedling rootstock, or BA29, or BA29/BH rootstocks, were planted in 2023. Soil characterization included textural, calcimetric, pH, and loss-on-ignition (LOI) analyses, together with multi-element profiling by X-ray fluorescence (XRF) and stable isotope determination (δ¹³C and δ¹⁵N ratios) by elemental analysis–isotope ratio mass spectrometry (EA-IRMS). During winter dormancy (December 2024), the youngest branches were likewise sampled to assess δ¹³C isotopic composition and C/N content. Plant physiological performance was subsequently evaluated through fast chlorophyll a fluorescence of leaves in May, June, and July 2025 to capture seasonal heatwave effects. LOI and calcimetric analyses confirmed organic carbon and carbonate contents compatible with adequate soil functionality. δ¹³C in branches ranged within a physiological range, from -28.3‰ to -25.7‰, across genotype/rootstock combinations. Chlorophyll fluorescence parameters, particularly the total performance index PI_tot showed marked variability among combinations and differentiated plant responses to the intense heatwave affecting Northern Italy in 2025.

These preliminary results, which are undergoing further elaboration, suggest that multi-temporal PI_tot determinations combined with branch δ¹³C analyses can provide a tool for the identification of optimal heatwave-resistant genotype-rootstock combinations.  However, the result must be considered specific to the Ferrara orchard context, characterized by well-defined soil properties within the alluvial Po River Plain, which is intrinsically heterogenous because of sediments of different origin and strong anthropic action. Further research will look for validation of the result in other soil contexts that are relevant to periculture in Emilia-Romagna.

 

Research funded by the European Union – NextGenerationEU, Ministero dell’Università e della Ricerca - Piano Nazionale di Ripresa e Resilienza, D.M. 630/2024.