Photochemical and Biochemical Characterization of Photosynthetic System and Nitrogen Partitioning: a Nitrogen-Use-Efficiency relationship in Citrus

• Grant number: 14/18151-8
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: October 01, 2015
• End date: January 31, 2019
• Field of knowledge: Agronomical Sciences - Agronomy - Crop Science
• Principal Investigator: Dirceu de Mattos Junior
• Grantee: Veronica Lorena Dovis
• Host Institution: Instituto Agronômico (IAC). Agência Paulista de Tecnologia dos Agronegócios (APTA). Secretaria de Agricultura e Abastecimento (São Paulo - Estado). Campinas , SP, Brazil

Abstract

Nitrogen (N) is an integral part of enzymes and proteins that regulate many biochemical processes in plants and consequently affects crop production. Supplied as a fertilizer, it is a nutrient of greatest consumption in the world agriculture. In citrus groves, up to 85% of N applied could be lost from the soil-plant-atmosphere system, mostly through leaching and volatilization, thus increasing risks of environmental pollution and costs to the growers. Therefore, in modern agriculture the challenge is to optimize production with N supply, considering either improved nitrogen fertilizer management (=fertilizer-efficiency-use) or plant production (=efficiency for absorption, transport and nutrient-use). Lemon trees (Citrus limon) have shown higher nitrogen-use-efficiency (NUE, kg of produced fruits/ kg of N absorbed or assimilated) when compared with sweet orange trees (C. sinensis). Amongst the factors that could affect NUE, we highlight the distribution of N assimilated between photosynthetic components and other destinations within the plant, as well as nutrient distribution between fractions associated with light absorption and biochemical fixation of CO2. The photochemical or biochemical efficiency may be, at least partially, the origin of better utilization of N assimilated by lemon trees. With the objective to explain the differences in nitrogen-use-efficiency between the two species, we propose the study of photochemical and biochemical characteristics, the N partitioning in leaf and plant, and dry mass partitioning of lemon and sweet-orange trees grown in pots, along one cycle of plant growth and submitted to two nitrogen levels (low and adequate). Daytime CO2 assimilation, photochemical efficiency, biochemical, stomatal and mesophyll limitations, N partitioning and accumulation, distribution of carbohydrates in plants and aquaporin gene expression will be evaluated in this study. With this project we expect to identify one or more physiological factors that could contribute to higher NUE in lemon when compared with sweet orange trees, and how each one contributes to the overall process of fruit production in Citrus. This knowledge could contribute to breeding or management programs for selecting more efficient varieties in nutrient consumption for the production in the field.

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

DOVIS, VERONICA L.; ERISMANN, NORMA M.; MACHADO, EDUARDO C.; QUAGGIO, JOSE A.; BOARETTO, RODRIGO M.; MATTOS JUNIOR, DIRCEU. Biomass partitioning and photosynthesis in the quest for nitrogen- use efficiency for citrus tree species. TREE PHYSIOLOGY, v. 41, n. 2, p. 163-176, FEB 2021. (14/50880-0, 14/18151-8)