Interactive effect of sodium bicarbonate and different Fe sources on micronutrients concentration in bell pepper plants

In order to investigate the effect of different Fe sources on micronutrients concentration, especially Fe, in bell pepper (Capsicum annuum L. cv. California Wonder), under alkaline conditions and hydroponic system, a factorial experiment was conducted based on a completely randomized design with two factors of sodium bicarbonate (NaHCO3) at three levels (0, 10 and 15 mM) and four forms of Fe fertilizer (FeSO4, Fe-EDTA, Fe-DTPA and Fe-EDDHA) all at 10 mM and three replications. According to the obtained results, NaHCO3 stress caused a reduction in P, Fe, Mn, Zn, Cu and K, and an enhancement in Na concentration. When the FeSO4 source was used, an increase in NaHCO3 concentration resulted in severe chlorosis of the plants, although Fe concentration in this treatment not only was not lower than Fe chelate- treated plants, but also it was higher in some cases. In the presence of NaHCO3 and FeSO4 treatment, the concentration of Mn, Zn and Cu in plants was higher than in plants treated with Fe-chelates, which might be due to the reduction of Fe competition with these elements in this treatment. Therefore, although the use of Fe chelates, especially Fe-EDDHA, for Fe provision in alkaline condition is recommended, but its high concentrations may cause Mn, Zn and Cu deficiency in plants.