Developing Strawberry Cultivars with Improved Water Use Efficiency

In a previous study, 10 Fragaria x ananassa cultivars and four accessions of F. chiloensis were exposed to water-limiting conditions c. 69% evapotranspiration (ETp) in comparison to control plants (100-130% ETp). Several different measurements were taken as indicators of water-use efficiency (WUE). The F. x ananassa cultivar 'Elvira' was found to have poor WUE, whereas the behaviour of the F. chiloensis clone 'BSP14' was less affected by the drought treatment. An interspecific cross was made to create a population that segregated for WUE-related traits. The progeny was screened for WUE over a two-year period and measurements taken to compare the effect on the plants when exposed to a drought stress. The mapping population showed genotypic variation for the parameters measured as indicators of WUE: stomatal conductance (estimated using thermal imaging), carbon isotope composition and accumulated above ground biomass per L of water applied. The latter two traits were found to be the most useful measurements of WUE for this study. The phenotypic data is currently being used to map quantitative trait loci (QTL) and identify closely linked molecular markers. Once the markers have been validated, it is envisaged that cultivars with improved WUE can be identified through the use of marker-assisted breeding.