Evaluation and reparametrization of mathematical models for prediction of the leaf area of &lt;i&gt;Megathyrsus maximus&lt;/i&gt; cv. BRS Zuri

Patrick Bezerra Fernandes,Carolina Marques Costa,Gelson Dos Santos Difante,Rodrigo Amorim Barbosa,Maria Da Graça Morais,Manoel Gustavo Paranhos Da Silva,Ana Beatriz Graciano Da Costa,Cauby De Medeiros-Neto,Antonio Leandro Chaves Gurgel,Juliana Caroline Santos Santana

doi:10.17138/tgft(8)214-219

Abstract

The aim of this study was to verify the precision and accuracy of 5 models for leaf area prediction using length and width of leaf blades of Megathyrsus maximus cv. BRS Zuri and to reparametrize models. Data for the predictor variables, length (L) and width (W) of leaf blades of BRS Zuri grass tillers, were collected in May 2018 in the experimental area of Embrapa Gado de Corte, Mato Grosso do Sul, Brazil. The predictor variables had high correlation values (P<0.001). In the analysis of adequacy of the models, the first-degree models that use leaf blade length (Model A), leaf width × leaf length (Model B) and linear multiple regression (Model C) promoted estimated values similar to the leaf area values observed (P>0.05), with high values for determination coefficient (>80%) and correlation concordance coefficient (>90%). Among the 5 models evaluated, the linear multiple regression (Model C: β0 = -5.97, β1 = 0.489, β2 = 1.11 and β3 = 0.351; R² = 89.64; P<0.001) and as predictor variables, width, length and length × width of the leaf blade, are the most adequate to generate precise and exact estimates of the leaf area of BRS Zuri grass.

Highlights

Studies involving the leaf areas of tillers are necessary to understand the processes of organogenesis, tissue expansion and photosynthesis of the forage canopy (Gastal and Lemaire 2015)
Non-destructive methods for measuring leaf area using regression equations are already used in several crops of agronomic interest, e.g. Theobroma cacao, Arachis pintoi, Stylosanthes spp., Calopogonium mucunoides, Neonotonia wightii and Coffea canefora (Santos et al 2014; Homem et al 2017; Espindula et al 2018)
The 95% confidence interval reveals that the observed leaf area values are highly correlated with leaf blade width (P

Summary

Introduction

Studies involving the leaf areas of tillers are necessary to understand the processes of organogenesis, tissue expansion and photosynthesis of the forage canopy (Gastal and Lemaire 2015). To estimate leaf area of the tiller directly, it is necessary to measure, via area integrator or by other means of image digitalization, all leaves on the tiller. In forage grasses, few published studies have evaluated and validated models to make accurate leaf area estimates (Toebe et al 2019; Bezerra et al 2020; Fernandes et al 2020a). Understanding of the interrelation of this grass with the environment must be investigated due to its high forage potential (Freitas et al 2018; Braga et al 2019; Silva et al 2020)

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