Genotype-by-environment interactions in major agronomic traits in sweet cherry: flowering and fruit quality

Flowering and fruit production in sweet cherry (Prunus avium) are strongly environment-dependent. Climate change, by inducing increased temperatures in winter and spring, can lead to strong yield and economic losses. In Winter, chilling requirements for dormancy release are not satisfied, which causes a delay in the release of dormancy and flowering disorders. In the Spring, it induces earlier blooming and a higher frost risk. Thus, increasing our knowledge about the genetic control of flowering and fruit-related traits in sweet cherry is a key step to obtain new cultivars well adapted to changing environment and to ensure the production of cherry in the future. The genetic determinism of flowering date and main agronomic and fruit quality traits such as maturity date, productivity, fruit weight, firmness and sugar/acidity content were evaluated. QTL detections were conducted on a sweet cherry F₁ population derived from the cross between cultivars ‘Regina’ and ‘Lapins’. The population, composed of 122 individuals, was planted in five locations across four European countries (France, Italy, Slovenia and Spain), constituting a multi-environment trial (MET) suitable for the study of genotype-by-environment interactions (G×E). Detection for flowering date confirmed the presence of a major QTL on linkage group 4 (LG4), explaining up to 40% of the phenotypic variation. This QTL is highly significant in all environments but Murcia, the only location characterized by a mild winter. In Murcia, another region was identified at the end of LG1 and is the major one, demonstrating the high effect of environmental conditions on the flowering process. Factor-analytical models were applied to the analysis of the MET and patterns of G×E were explored for all traits.