Effect of Fe 3+, Zn 2+ and Mn 2+ on ferric reducing capacity and regreening process of the peach rootstock Nemaguard (Prunus persica (L.) Batsch)

The peach rootstock Nemaguard is susceptible to lime-induced iron deficiency chlorosis. Under field conditions, application of ferric chelates to the soil is effective in correcting the Fe-deficiency symptoms. The objectives of this work were to study the induction of the root ferric reducing capacity and the relationship between chlorosis and leaf Fe concentration of plants grown hydroponically under different treatments. Results showed that bicarbonate-treated plants grown with a low Fe concentration increased their reducing capacity if they received additional Fe or Zn for a short period (15 h). However, the addition of Mn had no effect. When these Mn-treated plants were changed to nutrient solution with no bicarbonate and sufficient Fe, regreening was retarded several days in relation to the other treatments. In plants grown without bicarbonate, the reducing capacity was higher in plants grown with a low amount of Fe than in plants grown with either 0 Fe or sufficient Fe. In plants grown with bicarbonate and low Fe, the leaves became chlorotic and had low Fe concentration. When these plants received higher Fe supply, the regreening of the old leaves was not complete, though they had even higher Fe concentrations that the new developing leaves which were completely green. Results are discussed in relation to the Fe or Zn requirements of plants to induce reducing capacity and the incapacity of the cells from chlorotic leaves to absorb Fe and repair metabolic and structural damages.