Leaf area estimation from linear measurements in different ages of Crotalaria juncea plants

Abstract

The goal of this study was to estimate the leaf area of Crotalaria juncea according to the linear dimensions of leaves from different ages. Two experiments were conducted with C. juncea cultivar IAC-KR1, in the 2014/2015 sowing seasons. At 59, 82, 102, 129 days after sowing (DAS) of the first and 61, 80, 92, 104 DAS of the second experiment, 500 leaves were collected, totaling 4,000 leaves. In each leaf, the linear dimensions were measured (length, width, length/width ratio and length × width product) and the specific leaf area was determined through Digimizer and Sigma Scan Pro software, after scanning images. Then, 3,200 leaves were randomly separated to generate mathematical models of leaf area (Y) in function of linear dimension (x), and 800 leaves for the models validation. In C. juncea, the leaf areas determined by Digimizer and Sigma Scan Pro software are identical. The estimation models of leaf area as a function of length × width product showed superior adjustments to those obtained based on the evaluation of only one linear dimension. The linear model Ŷ=0.7390x (R 2 =0.9849) of the real leaf area (Y) as a function of length × width product (x) is adequate to estimate the C. juncea leaf area.

Mathematical Modeling to Estimation Leaf Area of Pimenta dioica from Linear Dimensions

“…This model presented higher R 2 values in the modeling and validation equation. The MAE and RMSE in the LW based models were smaller than in the equations obtained only when L or W was used individually and this same behavior was observed by Carvalho et al [5] studying the leaf area estimation for Crotalaria juncea, indicating greater precision in the models that use LW as independent variable. However, the power model stood out, being slightly superior to the linear models of first degree and quadratic confirming by the validation with lower values of MAE and RMSE and index d closest to one.…”

“…According to Pezzini et al [20] this high variability is desired since it indicates the presence of small, medium and large leaves in the sample, resulting in more precise mathematical models that estimate the leaf area with better precision of the different phases of the development of the plant. Thus, the adjustment of equations from models should be from a high range of leaf sizes collected in different parts of the plant [21,5] In relation to the leaves used for the validation, the values of the characteristics studied were between the range of the values establishment of the mathematical models, since the extrapolation of the data may lead to mis estimate of the leaf area [22].…”

“…Studies carried out for several species such as Jatropha curcas [4], Passiflora spp. [8], Vitis vinífera L. [10], Coffea canephora [9], Crotalaria juncea [5], Litchi chinensis Sonn. [13], Prunus armeniaca L. [14] and Annona cherimila Mill.…”

“…Among indirect methods, the estimation of leaf area through mathematical equation models has been widely used. These models are based on the relation between linear dimensions of the leaves as the length and the width or the interaction of both measures, and these models can be used in the field, under different stages of development and growth of plants, nondestructive manner, low cost and high degree of precision [5].…”

“…[8], Coffea canephora [9], Vitis vinífera L. [10], Passiflora mucronata [11], Annona cherimila Mill. [12], Crotalaria juncea [5], Litchi chinensis Sonn. [13] and Prunus armeniaca L. [14].…”