Effect of aluminium on bananas (Musaspp.) cultivated in acid solutions. II. Water and nutrient uptake

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Introduction. A previous paper showed that Al in the nutrient solution affected the growth, biomass production and chemical composition of bananas (Musa spp.). This paper aims at providing complementary results on the effect of Al on water and nutrient uptake by young banana plants. Materials and methods . Vitroplants of five cultivars (Grande Naine, Agbagba, Obino l'Ewai, Igitsiri and Kayinja) were grown for 40 d in a phytotron with a temperature close to that of their cropping areas. Dilute nutrient solutions without Al and with 78.5 μ M Al were supplied continuously with peristaltic pumps. Measurements of daily water and nutrient uptake were carried out twice a week. Rhizosphere acidification or alcalinisation were also monitored. Results and discussion . Aluminium reduced plant water uptake and cumulative detrimental effects were observed. After 40 d, water uptake was only 30-40% of the control. Without Al, nutrient uptake (Ca, Mg, K, P, NO3 -N, NH4 -N) increased with time, whereas Al inhibited the uptake of all elements, particularly Mg. As for water absorption, cumulative effects were observed: after 40 d, most nutrient uptake rates were reduced by more than 50% relatively to the control. The plantain bananas, Agbagba and Obino l'Ewai, were more resistant to Al than the others. Changes of temperature are likely to modify Al sensitivity as one cultivar, Kayinja, showed greater Al sensitivity at 28/25°C than at 24/20°C.