Characterization of early vigour in wild olive germplasm

Abstract

The use of dwarfing rootstocks represents an optimum mechanism to control the vigour of fruit tree species. Exceptionally, olive trees are grown on their own roots and due to excessive vigour, only a very limited number of cultivars have been successfully adapted to high-density orchards. Through prospection and phenotyping of different wild subspecies, a wide range of genetic variability of the species Olea europaea is being explored to identify genotypes that can be used as rootstocks to optimize intensive olive cultivation (e.g. low vigour, low susceptibility to Verticillium dahliae and high tolerance to abiotic stress). Here, early vigour parameters were studied in genotypes belonging to the subsp. europaea (var. sylvestris), guanchica, cuspidata and crosses of cuspidata x sylvestris. Homogeneous plants were obtained from in-vitro germinated seedlings and further micropropagation. After ex-vitro acclimatization and soil planting, plant height, diameter of the main axis at different heights and length of the longest shoot were measured eight months later. Significant correlations were obtained among the different vigour parameters and high values of broad sense heritability were obtained for all of them. A wide variability in vigour parameters was observed with some clear differences regarding the origin of the plant materials. Thus, the lowest vigour was obtained in sylvestris genotypes from Jaen (Spain) and Marrakech (Morocco) provenances, while the highest vigour was obtained in sylvestris genotypes from Cadiz (Spain) and genotypes from crosses cuspidata x sylvestris. However, a wide variability was obtained in all cases, particularly in genotypes from guanchica origin. Future works will be carried out in order to determine the relationship among vigour parameters measured at different plant age and to define the most efficient strategies for selection at early stages of breeding programs. Funding source: RECUPERA-2020 and contract agreement between IFAPA and Viveros Sevilla (CAICEM15-02).