UPTAKE OF ALUMINUM BY THE ROOT-TIPS OF AN AL-SENSITIVE AND AL-TOLERANT CULTIVAR OF ZEA-MAYS

Uptake and compartmentation of Al in the roots tips were investigated in two corn (Zea mays L.) cultivars (HS7777 single sensitive hybrid an d C525-M single tolerant hybrid). Seedlings were grown for 24 h in nut rient solution at pH 4.4 characterized by low ionic strength (2,06 mu M) and low Al3+ activity (10.3 mu M). The root elongation decreased st rongly for the sensitive cultivar. There were no differences in the co ntents of total Al in the entire roots between cultivars. Nonexchangea ble-Al and exchangeable-Al contents were higher in the root tips of HS 7777. The sensitive cultivar also showed higher total and exchangeable -Al contents in excised root tips in 180 min of Al uptake. Al uptake f or both cultivars increased in solution containing 0.1 mM of 2,4-dinit rophenol. Al contents were higher for the tolerant cultivar. (C) Elsev ier, Paris.