Physiological and oxidative stress responses of four potato clones to aluminum in nutrient solution

aluminum toxicity is a serious problem in brazilian soils and selecting potato clones is an important strategy to produce this crop on these kinds of soils. potato clones, macaca, smic148-a, dakota rose, and solanum microdontum, were grown in a nutrient solution (ph 4.0) with 0, 50, 100, 150 and 200 mg al l-1. after 7 d, al concentration in both root system and shoot of all clones increased linearly with increasing al levels. based on relative root growth, s. microdontum and smic148-a were considered al-tolerant clones, whereas macaca and dakota rose were considered al-sensitive. shoot growth in macaca linearly decreased with increasing al levels. root h2o2 concentration in both al-sensitive clones increased with increasing al supply, whereas in al-tolerant clones it either decreased (smic148-a) or demonstrated no alteration (s. microdontum). shoot h2o2 concentration increased linearly in macaca, whereas for dakota rose it showed a quadratic relationship with al levels. on the other hand, shoot h2o2 concentration in the al-tolerant clones either demonstrated no alteration (s. microdontum) or presented lower levels (smic148-a). root catalase (cat) activity in both al-sensitive clones increased with increasing al levels, whereas in al-tolerant clones it either demonstrated no alteration (smic148-a) or presented lower levels (s. microdontum). shoot cat activity in the s. microdontum increased curvilinearly with increasing al levels. in all potato clones, chlorophyll concentration showed a curvilinear response to al supply, where in al-sensitive clones it decreased upon addition of al exceeding 100 mg l-1, but in smic148-a it increased at levels between approximately 100 and 150 mg l-1, and decreased in s. microdontum regardless of the al level. carotenoid concentrations in the al-sensitive clones were linearly decreased with increasing al levels. aluminum supply caused root lipid peroxidation only in the al-sensitive clones, whereas in the shoot it increased linearly i