Zinc Fertilizers and Additives for Foliar Fertilization of Cocoa Seedlings

Abstract

Foliar fertilization is an interesting strategy for nutrition with micronutrients in perennial plants; among the micronutrients, zinc (Zn) deficiency is the most frequent in cocoa trees (Theobroma cacao L.). The present study aimed to evaluate the efficiency of Zn sources through foliar application for the cocoa crop. The experiment was carried out in a randomized block design, with 10 treatments and four replicates. Treatments were: foliar fertilizations containing 1 g L-1 of Zn using two inorganic sources (chloride and sulfate), in the presence or absence of additives (urea and sucrose); two organic sources (Zn-EDTA, and from chloride and sulfate); soil fertilization with 8 mg dm-3 of Zn, and a control (without addition of Zn). Foliar fertilizations with Zn were monthly applied for five months, and the experiment was conducted for 210 days. The results were subjected to analyses of variance and contrast. Zn fertilization, regardless of the form of application, increased Zn contents and accumulations in the leaves. Zn fertilization in the soil, at planting, led to a recovery rate by the plant similar to the mean value caused by foliar fertilizations. ZnCl2 caused higher Zn contents and accumulations in the leaves and was more efficient than sulfate and EDTA; addition of urea to the ZnSO4 solution increased Zn accumulation in the leaves, whereas addition of sucrose to the ZnCl2 solution reduced Zn content in the leaves.

Zn Nutrition of Vitis vinifera White Grapes: Characterization of Antagonistic and Synergistic Interactions by µEDXRF Tissue Analyses

“…Nowadays, to meet the food necessities according to population growth, different techniques are being explored to increase agricultural crops yields [16]. Accordingly, mineral nutrition is among the most used agricultural techniques to obtain higher yields and quality [17], namely Zn fertilization through soil and/or foliar applications [18]. Most studies were carried out with soil fertilization, implying the influence of physicochemical and biological soil properties, such as pH, water, structure, cation exchange capacity, redox conditions and activity of microorganisms [19].…”

Stable Isotope Analyses Reveal Impact of Fe and Zn on Cd Uptake and Translocation by Theobroma cacao

“…In regard to cacao, a positive correlation has been found between Zn and Cd in leaves, as well as between the Zn in beans and Cd in leaves [ 37 ]. Soil and foliar Zn treatments have been studied both to overcome symptoms of Zn deficiency [ 38 , 39 ] and to mitigate against Cd toxicity [ 20 ]. It was found in a pot experiment that increasing soil Zn concentrations decreased both root uptake of Cd and translocation to the leaves [ 20 ].…”