Physiological and growth responses to water deficits in cultivated strawberry (Fragaria × ananassa) and in one of its progenitors, Fragaria chiloensis

Abstract

Cultivation of strawberry (Fragaria×ananassa) requires irrigation. Improving crop water use efficiency (WUE) is important for future production. Fragaria chiloensis, a progenitor of cultivated strawberry, grows in sandy soils, and may prove useful in breeding for improved WUE. Little, however, is known about variation in drought tolerance within this species. This research explores drought tolerance in a range of F. chiloensis and F.×ananassa genotypes. Four cultivars of F.×ananassa and four accessions of F. chiloensis were compared when well watered, and when subjected to a water deficit (65% of evapotranspiration). New leaf production, stomatal conductance, and photosynthetic rate were significantly reduced under water deficit, and also significantly differed between genotypes. A significant interaction of genotype and irrigation was found for transpiration rate, leaf area and dry mass, production of runners, predawn water potential, a measure of transpiration efficiency (shoot biomass produced per litre water transpired), and carbon isotope composition, indicating that some genotypes were more severely affected by water deficit than others. The South American F. chiloensis accession ‘Manzanar Alto’ had a similar rate of transpiration to the commercial cultivars, but the remaining (North American) F. chiloensis accessions used far less water than the F.×ananassa. Well-watered F. chiloensis plants used less water than water-limited plants of the F.×ananassa cultivar ‘Florence’. Transpiration efficiency of the F. chiloensis accession ‘BSP14’ was improved by water deficit: this was the only genotype not to show a reduction in leaf area and dry mass under water deficit. Greater drought resistance in three F. chiloensis accessions compared to F.×ananassa results from a conservative vegetative growth strategy, reducing loss of water.