The role of molybdenum on nitrogen use efficiency and root growth of citrus trees

• Grant number: 16/08160-5
• Support Opportunities: Scholarships abroad - Research Internship - Scientific Initiation
• Start date: July 04, 2016
• End date: November 03, 2016
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Rodrigo Marcelli Boaretto
• Grantee: Nataniel Victor Lopes
• Supervisor: Ana Quinones Oliver
• Host Institution: Instituto Agronômico (IAC). Agência Paulista de Tecnologia dos Agronegócios (APTA). Secretaria de Agricultura e Abastecimento (São Paulo - Estado). Campinas , SP, Brazil
• Institution abroad: Instituto Valenciano de Investigaciones Agrarias (IVIA), Spain
• Associated to the scholarship: 14/22499-0 - Effect of molybdenum and sources of nitrogen supply in citrus via fertigation, BP.IC

Abstract

The nitrogen (N) absorption by the plant is linked to several factors such as its availability in the soil to the root, since the physicochemical properties of the soil (pH, texture, organic matter content) affect the nutrient availability for plant. In the plant, once the N is absorbed in the form of nitrate it must be reduced to an assimilable form in which the enzyme nitrate reductase acts by reducing nitrate to nitrite. For this reaction to happen the presence of molybdenum (Mo) as enzyme cofactor is needed. This proposal aims to evaluate the efficiency of two contrasting rootstocks on N absorption and Mo management. The experiment will be conducted in a greenhouse in a completely randomized experimental design (2 x 2 x 2), with two-years-old mandarin Clementine Nules grafted on two different rootstock (one commonly used in Spain and another in Brazil), with two types of soil (acid - pH <5.0 and alkaline - pH> 7.0) and two molybdenum levels (with and without Mo fertigation). The plants will be transplanted into 30 L pots and cultivated for 60-70 days. The N will be supplied in the form of calcium nitrate (4% 15N atoms). It will be introduced a plexiglass tube into the soil to scanner the root growth. In the aboveground of the plant, will be periodic measurements of height, canopy volume, leaf area index, stem diameter, and nitrate reductase activity in the leaf. At the end of the trial the plants will be destructively harvested to quantify total dry biomass, N and Mo uptake and the N use efficiency (15N). (AU)