Master's Dissertation
DOI
https://doi.org/10.11606/D.11.2023.tde-12092023-095234
Document
Author
Full name
Mateus Ormondes de Magalhães
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 2023
Supervisor
Committee
Zocchi, Silvio Sandoval (President)
Ferreira, Iuri Emmanuel de Paula
Leandro, Roseli Aparecida
Title in Portuguese
Polinômios fracionários e planejamento de Littell e Mott em ensaios de nutrição mineral de plantas
Keywords in Portuguese
Panicum maximum
Modelos de regressão
Abstract in Portuguese
Title in English
Fractional polynomials and Littell and Mott design in plant mineral nutrition assays
Keywords in English
Panicum maximum
Productivity
Regression models
Soil fertility
Abstract in English
Forage plants play an important role in feeding livestock and in the economy for producers. They provide essential nutrients to animals and have good regrowth and adaptation capabilities. The production of these plants is directly related to soil fertility, with emphasis on two nutrients: nitrogen and potassium. To maximize productivity and optimize the use of fertilizers, fertilizer trials are carried out to determine the most efficient doses. In these essays, the incomplete factorial scheme 5k from Littell e Mott (1975) is used. For the statistical analyzes of a set of data from trials of fertilization with two nutrients, they erroneously use first and second order polynomial models, as these models often present a lack of adjustment due to the behavior of plant growth when subjected to doses of these nutrients. An alternative is the fractional polynomials proposed by Royston e Altman (1994), as a more general class of regression models. In this work, we therefore propose a more general approach to these polynomials, both for the adjustment and for the selection of models. The methodology was implemented using the Rstudio (R Core Team, 2022) interface and illustrated through a set of data from fertilization trial involving five different doses of nitrogen and potassium in Panicum maximum Jacq plants. cv. Mombasa. The analyzes showed that the fractional polynomial models offer several advantages in relation to the polynomial models, among them, greater flexibility of the models to obtain an adequate model for plant growth data and to determine the doses that optimize the production of plants, in particular, in this case, for forage plants.