Aluminum stress tolerance in potato genotypes grown with silicon

Potato cultivation is widespread around the world, being exposed to several abiotic stresses, including soils with high aluminum (Al) availability. Silicon (Si) is recognized for alleviating the stress caused by Al in various plant species. Thus, the aim of this study was to investigate the potential of Si to mitigate the oxidative stress caused by Al in potato genotypes, exhibiting differential sensitivity toward this element. Plants of the Al-sensitive genotype (SMIJ319-7) and Al-tolerant genotype (SMIF212-3) were grown for two weeks in a hydroponic system with the nutrient solution containing combinations of Al (0 and 1.85 mM) and Si (0, 0.5 and 1.0 mM). At the end of the experiment, photosynthetic parameters, pigment content, root and shoot growth, superoxide dismutase and guaiacol peroxidase activity and lipid peroxidation were evaluated. In both potato genotypes Al inhibited root and shoot growth and decreased all photosynthetic parameters and superoxide dismutase activity. Silicon was able to partially alleviate the damage caused by Al in parameters of root growth in the Al-tolerant genotype while increasing the activity of antioxidant enzymes and mitigating the Al-induced damage to membrane lipids in roots and shoot in both genotypes. The Al-tolerant genotype showed greater water use efficiency and transpiration rate in control conditions as compared to the Al-sensitive genotype. These data indicate that Si application can improve the defense ability of the tested potato genotypes against Al toxicity and that the Al-tolerant genotype is more responsive to Si.