Foliar Iron Fertilization of Peach (Prunus persica (L.) Batsch): Effects of Iron Compounds, Surfactants and Other Adjuvants

Abstract

Experiments to assess the capability of different combinations of iron (Fe) compounds and adjuvants to provide Fe via foliar application to Fe-deficient plants have been carried out. A total of 80 formulations containing (1) one of five Fe-compounds [FeSO 4 Á7H 2 O, Fe(III)-citrate, Fe(III)-Ethylenediaminetetraacetic acid (EDTA), Fe(III)-Diethylenetriamine pentaacetic acid (DTPA), Fe(III)-Iminodisuccinic acid (IDHA)], (2) a surfactant (Mistol, alkyl-polyglucoside1 or alkyl-polyglucoside2), and (3) an adjuvant (glycerol, methanol or glycine-betaine) were studied with respect to leaf wetting ability and surface tension. From the initial formulations only 26 resulted in adequate leaf wetting, 20 with alkylpolyglucoside2 and 3 each with Mistol and alkyl-polyglucoside1, and some of them (four with alkyl-polyglucoside2, one with Mistol, and three with alkyl-polyglucoside1) were found to have inadequate surface tension values for use as foliar fertilizers. In a second experiment, 20 formulations containing alkyl-polyglucoside2 and one each of the five Fe-compounds and adjuvants listed above, were used for a foliar experiment with Fe-deficient peach trees [Prunus persica (L.) Batsch] grown under field conditions. Iron-deficient shoots were sprayed only once and leaf re-greening was assessed over 6 weeks for leaf chlorophyll content (via SPAD measurements) and percentage of green leaf area (via image analysis). Foliar Fe application always resulted in leaf Chl increases, although different degrees of re-greening were observed for the various Fe-compounds tested. Best results were obtained after treatment with formulations containing (in a decreasing order): Fe(II)-sulfate, Fe(III)-citrate, Fe(III)-EDTA, Fe(III)-IDHA, and Fe(III)-DTPA. A positive effect of adding glycerol, methanol or glycinebetaine was often observed, although the effect depended on each Fe-containing compound, indicating the existence of significant interactions between spray components. Results are of importance while trying to critically evaluate the potential of Fe sprays as a viable strategy to remedy plant Fe deficiency under field conditions.

Development and recovery of iron deficiency by iron resupply to roots or leaves of strawberry plants

“…However, when Fe was supplied to leaves the regreening was only partial, and Chl values were lower in new developed leaves compared to plants always grown with Fe (Fe10). Partial re-greening following foliar sprays was previously observed in orange and peach trees [10,11,22]. To be effective, the exogenous Fe applied to leaves must cross the foliar barrier to enter cells and must then be integrated in plant metabolism [14].…”

“…Crops commonly affected by Fe deficiency when grown in calcareous soils include apple, blueberry, cherry, citrus, corn, grape, turf and pasture grasses, peach, pear, plum, quince, sorghum, soybean, and strawberry, resulting in impaired growth and yield [5,[7][8][9][10][11]. On calcareous soils, strawberry production may be seriously affected by induced Fe-deficiency.…”

Evaluation of 59Fe-lignosulfonates complexes as Fe-sources for plants

“…Photoreduction of this latter Fe-source, occurring at high light intensity (Norvell 1991), could explain the higher 59 Fe accumulation. Moreover, the lower uptake rates from 59 Fe-LS might be related to a limited penetration of the leaf cuticle (Fernández et al 2006) Data are means ± SD of three replicates. Different letters within the same column denote significant differences among the treatments (P<0.05) Cucumber leaves were also able to absorb 59 Fe from 59 Fe-LS at levels similar to those obtained with 59 Fe-EDTA (Table 6).…”

“…This type of applications have been tested by several authors with synthetic chelates, natural complexes and inorganic salts (Pérez-Sanz et al 1996;Pestana et al 2001;Nikolic et al 2003;Álvarez-Fernández et al 2004;Fernández et al 2006) with variable results, due to the diverse factors controlling foliar absorption (characteristics concerning the treated leaf, the type of molecule applied, surfactant, etc.) and difficulties in achieving an optimum formulation of foliar fertilizer.…”

Improving the performance of calcium-containing spray formulations to limit the incidence of bitter pit in apple (Malus x domestica Borkh.)

“…To record the surface tension, solutions were prepared immediately before measurement to avoid the occurrence of interactions among active ingredients and formulation adjuvants (Fernández et al, 2006). Data were recorded with a DSA 100 Drop Shape Analysis System (Krüss GmbH, Hamburg, Germany) with 10 repetitions per treatment.…”