Short-term Aluminum Stress Differentially Affects the Photochemical Efficiency of Photosystem II in Highbush Blueberry Genotypes

Aluminum (Al) toxicity is a major agronomic problem in acid soils. Most studies regarding Al stress focus on phenomena occurring in the roots; however, less is known about the effects of Al stress on photosynthetic apparatus functionality. Our aim was to rank three highbush blueberry (Vaccinium corymbosum) cultivars according to their tolerance to acid and Al stresses. Additionally, the levels of Al toxicity for highbush blueberry were established. 'Brigitta', 'Legacy', and 'Bluegold' were grown in a greenhouse in hydroponic solutions containing different Al concentrations (0, 25, 50, 75, and 100 mu M) for 0 to 48 h and were allowed to recover (without Al) over 24 h. In all Al-treated cultivars, root growth inhibition was found at the highest Al treatment. However, 'Brigitta' also showed root growth up to 75 mu M Al. Photochemical parameters decreased substantially due to Al treatments in 'Bluegold' (up to 98%, inhibition) and 'Legacy' (up to 80% inhibition) without total recovery. In contrast, 'Brigitta' showed a better photosystem II performance and root growth than the other cultivars. These results suggest that 'Brigitta' is the best cultivar for use in acid soils with Al toxicity, followed by 'Legacy'. 'Bluegold' was highly sensitive to Al stress. In addition, Al toxicity levels for blueberries depend on the genotype studied.