Effect of molybdenum and sources of nitrogen supply in citrus via fertigation

• Grant number: 14/22499-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: January 01, 2015
• End date: December 31, 2016
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Rodrigo Marcelli Boaretto
• Grantee: Nataniel Victor Lopes
• Host Institution: Instituto Agronômico (IAC). Agência Paulista de Tecnologia dos Agronegócios (APTA). Secretaria de Agricultura e Abastecimento (São Paulo - Estado). Campinas , SP, Brazil
• Associated scholarship(s): 16/08160-5 - The role of molybdenum on nitrogen use efficiency and root growth of citrus trees, BE.EP.IC

Abstract

Molybdenum (Mo) is directly related with the nitrogen (N) metabolism in plants, therefore it is part of enzymes such as nitrate reductase (NR). NR acts as a catalyst in the reduction of nitrate, which is in the N form absorbed by the plant, to nitrite and the enzime activity is used as an indicator of Mo bioavailable and N assimilation by plants. The nitrite is reduced to ammonia, and in this form the N is incorporated into the plant. This proposal aims to assess whether the supply of Mo interferes with the N use efficiency of citrus plants, fertilized with N sources in nitrate and ammonium form. The experiment will be carry out in a greenhouse with seedlings of Valencia on Swingle citrumelo, transplanted to pots containing 18 dm3 of sandy loam soil. The experiment will be set up in 4x2 factorial design, with three sources of N [(NH4) 2SO4, NH4NO3 and Ca (NO3) 2] plus a control without N application and two levels of Mo supply in soil (without Mo and 0.25 g Mo per plant), with five replicates per treatment. In roots and leaves of the new flushes determinations of the NR activity and indirect measurements of chlorophyll will be held. At the end of the experiment the plants will be harvested and the total biomass, Mo concentrations, nitrate and ammonium in different tissues will be determined. The results will help determine whether application of Mo, can influence the N use efficiency by citrus trees and the N fertilizer source, which can impact on fertilizer use efficiency, gains in productivity and profitability of citrus orchards.