Foliar Application of ZnSO4 and CuSO4 Affects the Growth, Productivity, and Fruit Quality of Washington Navel Orange Trees (Citrus sinensis L.) Osbeck

Sherif Fathy El-Gioushy,Rokayya Sami,Reda M Y Zewail,Amina A M Al-Mushhin,Khadiga Ahmed Ismail,Mohamed S Gawish,Hanan M Abou El-Ghit

doi:10.3390/horticulturae7080233

Abstract

The goal of this study was to examine how to improve the vegetative growth, nutritional status, productivity, and fruit quality of Washington navel orange trees by examining the effect of foliar application of ZnSO4 (0, 300, and 600 mg/L) solutions in combination with CuSO4 (0, 200, and 400 mg/L) solutions on Washington navel orange trees, which were 11 years old and grown in clay loam soil with a surface irrigation system. The results showed that all the investigated measurements responded specifically to each investigated factor. ZnSO4 elicited a stronger and more effective response than CuSO4. Nonetheless, the response varied only slightly or moderately from one measurement to the next. In terms of the interaction effect between ZnSO4 and CuSO4 concentrations, the effect of each investigated factor was directly reflected in its combinations, with ZnSO4 (600 mg/L) and CuSO4 (200 and 400 mg/L) being the most effective for the majority of the measurements under consideration. When the highest level of ZnSO4 was combined with the highest level of CuSO4, the highest values for the various vegetative growth parameters shoot length and diameter, number of leaves per shoot, leaf area, and total assimilation area per shoot were obtained. As a result, the nutritional status (the highest total leaf chlorophyll and leaf mineral contents) was significantly coupled with the treatment of 600 mg/L ZnSO4 in combination with 400 mg/L CuSO4. Moreover, the combinations of the highest ZnSO4 concentration (600 mg/L) and CuSO4 concentration (400 mg/L) exhibited the greatest statistical values of the measurements of fruiting aspects as well as fruit quality. Consequently, it can be recommended that using 600 mg/L ZnSO4 in combination with 400 mg/L CuSO4 as a foliar spray on monthly basis during the period from March to July could be safely recommended under similar environmental conditions and horticulture practices adopted in the present experiment.

Highlights

Plants require micronutrients, such as zinc, manganese, copper, boron, and molybdenum
During the 2019 and 2020 experimental seasons, 11-year-old Washington navel orange trees budded on Sour orange rootstock were planted 5 × 5 meters apart (168 trees/fed.) in a private orchard under surface irrigation located in the Toukh region, Qalyubia Governorate, Egypt
This study was designed to determine the effects of different ZnSO4 and CuSO4 concentrations on the growth, nutritional status, and fruiting aspects of Washington navel orange trees

Summary

Introduction

Plants require micronutrients, such as zinc, manganese, copper, boron, and molybdenum. Zinc added to alkaline soil is typically adsorbed or precipitated on the surface and does not pass to the root region, according to research. Because citrus is a deep-rooted tree, applying micronutrients to the soil may be ineffective [1]. Zn foliar application increased sweet orange fruit yield compared with the control treatment [2]. Foliar treatments are required in cases of immobilization processes, which render the application to soils ineffective. Citrus development has been affected by micronutrients such as zinc (Zn) and copper (Cu) applications. These components influence the biochemical functions of the plant system. Zn is an important micro factor essential for plants because of its role in tryptophan synthesis, a precursor to indole acetic acid synthesis [5]

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Conclusion