Long-term Aluminum Exposure Effects on Physiological and Biochemical Features of Highbush Blueberry Cultivars

We compared the aluminum tolerance of two highbush blueberry (Vaccinium corymbosum) cultivars, Legacy and Bluegold, grown in a greenhouse in Hoagland's solution with increasing concentrations of AI (0, 25, 50, 100, and 200 mu M) for 7 to 20 days, using root lipid peroxidation (LP), radical scavenging activity (RSA), AI uptake by roots, and relative growth rate (RGR) as criteria. Leaf physiological [photochemical and non-photochemical parameters of photosystem II (PSII)1 and biochemical (pigments, LP, RSA, and total soluble carbohydrates) responses to AI stress were also analyzed and then a principal component analysis (PCA) was performed. The results indicated that 'Bluegold' showed the highest AI uptake and LP in roots and a lower RGR in contrast to 'Legacy'. The photochemical parameters were more affected in 'Bluegold' than in 'Legacy', particularly at the beginning of the experiment. At this point, a sharp increase in RSA was found in 'Legacy'. According to these parameters, 'Legacy' was more AI tolerant than 'Bluegold'. PCA revealed that among the underlying processes affected by AI toxicity in the highbush blueberry, the photochemical efficiency of PSII followed by modifications of photosynthetic pigment contents are of greatest significance after long-term AI stress. Additionally, RSA plays an important role in the long-term acclimation response mechanisms to AI stress in highbush blueberry leaves.