Zinc sources and nutritional status of citrus: supply efficiency through fertigation and foliar fertilization

• Grant number: 13/08288-3
• Support type: Regular Research Grants
• Duration: July 01, 2013 - December 31, 2015
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal researcher: Rodrigo Marcelli Boaretto
• Grantee: Rodrigo Marcelli Boaretto
• Home Institution: Instituto Agronômico (IAC). Agência Paulista de Tecnologia dos Agronegócios (APTA). Secretaria de Agricultura e Abastecimento (São Paulo - Estado). Campinas , SP, Brazil
• Assoc. researchers: Jose Antonio Quaggio

Abstract

Zinc (Zn) is an important micronutrient for citrus production, particularly in young orchards. The prevention or correction of its deficiency is made either by soil or leaves application. Few studies have evaluated the application of metallic micronutrients applied to the soil in citrus orchard, and which showed responses on increased leaf nutrient levels. These responses depend on the interaction of nutrients with the soil colloidal matrix, and micronutrient sources and rates, which knowledge is important to the establishment of revised recommendations for citrus best management. Once in high yield citrus groves the micronutrient demand is outstandingly higher. Based on the above, the overall objective of the project is to develop information which allows recommendations of different Zn sources to the new citrus production systems. The specific objectives are: i) to evaluate ways of supply and sources of Zn applied either by fertigation or foliar fertilization; ii) to evaluate the efficiency of different Zn sources, supplied either by fertigation or foliar spray, on plant growth, fruit quality and nutritional status of citrus; iii) compare if the reduction of Zn nitrate rate applied in the leave, supplies the Zn demand of citrus tree compared to higher rate of Zn sulfate. To achieve these goals will be given continued in an experiment that have been conducted in a commercial citrus orchard of Sweet orange tree on Sunki mandarin, planted in May 2008. The trial is in its third year of evaluation and was established in a factorial design with three Zn sources [ZnSO4, Zn (NO3)2 and Zn-EDTA] and two ways of application (fertigation and foliar spread). In the project will be evaluated: soil chemical attributes; tree growth; production and fruit quality; nutrient concentration in the leaf and sap extract; and nutritional status of Zn using biochemical markers. The results obtained in the experiment will contribute to revisions of the current Zn recommendations to citrus orchards, which promote increasing in the fertilizer use efficiency and thus maximize the productivity of citrus orchards (AU)