Organic acids combined with Fe-chelate improves ferric nutrition in tomato grown in calcisol soil

Abstract

Plants developed in calcisol soils have limitations in iron nutrition, so exogenous applications of organic acids plus iron chelate can be an alternative. With the objective of knowing the answer of adding organic acids in the fertilizer solution plus a ferric chelate on the characteristics of the ferric nutrition of tomato plants developed in the calcisol soil the present experiment was established. We conducted the experiment in two stages, in the first stage studied different concentration of some organic acids: citric acid (CA), oxalic acid (OA), salicylic acid (SA), and humic complexes (HCs) combined with a FeEDDHA iron chelate, we included treatment control FeEDTA and FeEDDHA and treatment without iron in the fertilizer solution. In the second stage, we compared the best concentrations of organic acids in combination with FeEDTA iron chelate; we used to treatment control FeEDTA and FeEDDHA, and a control treatment without iron in the fertilizer solution. The best concentrations were CA 10−4 M, OA 10−4 M, SA 10−5 M, and HC 0.4 ml l−1. In the second stage, the addition of CA+FeEDTA and HC+FeEDTA increased SPAD units, chlorophyll and vitamin C contents and fruit quality improved. An increase content of Fe, Zn, and Mn in leaves was presented with treatment CA+FeEDTA and HC+FeEDTA. Addition of CA+FeEDTA improved the oxidation-reduction potential, pH and electrical conductivity (EC) of plant leachates, followed by HC+FeEDTA. Applications of CA and HC in the nutrient solution in combination with EDTA-type chelate improved the characteristics of the ferric nutrition of tomato plants developed in calcisol soil.