W. Murcott scion, budded onto two rootstocks, was evaluated under high pH conditions supplied with different Fe levels. Plant dry weight, leaf area, iron chlorosis symptom scale, leaf chlorophyll concentration, net photosynthetic rate, and ferric-chelate reductase (FCR) activity variables were investigated under high pH conditions. Control plants (T1) produced the most leaf area, whereas plants grown without Fe (T2) produced the least. Dry weight was highest in 'Volkameriana' T1 (control) plants and lowest in 'Swingle citrumelo' T3 (10 mu M Fe and 7.8 pH) and T2 (0 mu M Fe and 7.8 pH) treatments. Significant differences in SPAD and iron chlorosis scale reading were found between rootstocks and treatments. Treatments significantly affected the net photosynthetic rate of the W. Murcott mandarin. Moreover, it was found that tolerant rootstock had higher FCR activity in application T2 than in applications T3 and T4 (100 mu M Fe and 7.8 pH). The data of the present study suggested that scion budded onto Volkameriana rootstock showed a higher tolerance to iron deficiency than those budded onto Swingle citrumelo under high pH conditions.