INTERSPECIFIC RESPONSES OF MARIGOLD TO MANGANESE AS INFLUENCED BY NITROGEN-SOURCE

Responses of two hydroponically grown marigold species, Tagetes erecta L. 'Pumpkin Crush' and T. patula L. 'Janie Yellow', to Mn concentrations of 0.5 mg.liter-1 or 10 mg.liter-1 with KNO3 and Ca(NO3), (NO3 source) or NH4NO3 as the N source were investigated. In both species, Mn uptake was enhanced with the NO3 source while reduced with NH4NO3. With Mn supplied at 0.5 mg.liter-1 and NO3 as the N source, T. erecta absorbed twice the Mn per gram of dry matter as T. patula. T. erecta accumulated higher concentration of Mn in the shoot than in the root irrespective of the N source. T. patula accumulated higher concentration of Mn in the roots with the NO3 source while NH4NO3 shifted the Mn accumulation to the shoot. Growth of both species was suppressed with 10 mg Mn/liter and the suppression was greater with the NO3 source than with the NH4NO3. These results indicate an interspecific response to Mn concentration as well as an N source influence on the uptake of Mn in marigold grown under hydroponic conditions.