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Integrated effects of K and na application on initial growth of eucalyptus seedlings submitted to water stress: water use efficiency, gas exchange and ´13C isotopic variation

Grant number: 17/24410-4
Support type:Scholarships in Brazil - Master
Effective date (Start): July 01, 2018
Effective date (End): July 31, 2019
Field of knowledge:Agronomical Sciences - Forestry Resources and Forestry Engineering
Cooperation agreement: Coordination of Improvement of Higher Education Personnel (CAPES)
Principal Investigator:José Lavres Junior
Grantee:Nikolas de Souza Mateus
Home Institution: Centro de Energia Nuclear na Agricultura (CENA). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

In Brazil, fertilizer application is one of the main factors for achieving high productivity in commercial Eucalyptus plantations, since it is frequently carried out in soils with water stress and low chemical fertility. Potassium (K) is the most required macronutrient by the Eucalyptus plant, while sodium (Na), can partially substitute some physiologic functions of K, influencing directly the water use efficiency (WUE) of plants. Thus, the present study aims to evaluate, in a greenhouse, the response of four contrasting eucalypt clones regarding to water stress tolerance to the partial replacement of K by Na in different water regimes. Plant growth, nutrient concentration, gas exchange (A-CO2 assimilation rate, gs-stomatal conductance, E-transpiration and A/ci-RUBISCO carboxylation efficiency), WUE, chlorohpyl and polyamines content, stomatal density (DE), leaf water potential (¨w), leaf area (AF) and isotopic carbon fractionation (´13C) will be measured. It is expected that the different clones respond positively to the partial substitution of K by Na, with an increase in the efficiency of CO2 assimilation and in the initial growth of eucalyptus and that drought-tolerant clones have smaller reduction in growth compared to sensible clones, as well as greater efficiency of absorption and utilization of K and Na. (AU)