Metabolism of Phosphorus by Barley Seedlings'

increases over controls were found when root segments were incubated in phosphorus solutions containing 10-3 A D)NP ancd at lowx temlperatture. The increased Pi in Al-roots did niot result in an increase in the total amounit of l)hosphorus incorporated into phosphorylated compounds. Aluminum treatnment miiarkedly decreased the incorporation of P32 into sigar phosl)hates but increased the pool size of ATP and other nucleotide triphosphates present in the roots. The specific activities of P32 in ATP in Al-roots and( controls wvere similar inidicating that the rates of ATIP synthesis wvere similar in eaclh case. Preliniinarv investigation.s showed that aluminum citrate inhibited both lpurified yeast liexokilase and phosphorylated sgtiar pro(ldtution by crud(le nllitoclloli(lrial extracts fron harley roots. T'he results suggest that there are 2 reactionis betwxecil aluminum and i phosphorts: I ) at the cell suirface or in the free space which results in the fixation of phosphate by