Allometric models for non‐destructive leaf area estimation in coffee (Coffea arabica and Coffea canephora)

Abstract

We aimed to evaluate the currently used allometric models, as well as to propose a reliable and accurate model using non-destructive measurements of leaf length (L) and/or width (W), for estimating the area of leaves of eight field-grown coffee cultivars. For model construction, a total of 1563 leaves were randomly selected from different levels of the tree canopies and encompassed the full spectrum of measurable leaf sizes (0.3-263 cm 2 ) for each genotype. Power models better fit coffee leaf area (LA) than linear models. To validate the model, an independent data set of 388 leaves was used. We demonstrated that the currently used allometric models are biased, underestimating the area of a coffee leaf. We developed a single power modelbased on two leaf dimensions [LA = 0.6626 (LW) 1.0116 ; standard errors: b 0 = 0.0064, b 1 = 0.0019; R 2 = 0.996] with high precision and accuracy, random dispersion pattern of residuals and also unbiased, irrespective of cultivar and leaf size and shape. Even when the L (but not width) alone was used as the single leaf dimension, the power model developed still predicted with good accuracy the LA but at the expense of some loss of precision, as particularly found for 8% of the leaves sampled with length-to-width ratios below 2.0 or above 3.0.

A non-destructive method for estimating onion leaf area

“…The use of non-linear regression models is less extensive for estimating leaf area. Thus, Antunes et al (2008) used non-destructive measurements of leaf length and width for estimating the area of leaves of eight field-grown coffee cultivars. In this case, they obtained better results using power models than linear models.…”

Non-destructive models to estimate leaf area on bell pepper crop

“…GALINDO & CLAVIJO (2007), they mentioned as well, that the latter presents a greater precision in the plant growth evaluation, as it facilitates its implementation in acicular or tubular leaves, in addition of performing the evaluation without destroying the plant leaves. This is a very consistent method compared to other indirect methods, taking into account that the estimation of leaf area from direct measurements have applicability even today, besides destructive methods usually required the collection of a large number of leaves, that in turn implies the use of expensive equipment and a longer dataset (ANTUNES et al, 2008).…”

Seletividade e controle de plantas daninhas com oxyfluorfen e sulfentrazone na implantação de lavoura de café

“…Isso ocorre porque a presença de plantas daninhas na vizinhança do cafeeiro jovem limita o acesso da cultura aos recursos do ambiente, especialmente luz e nutrientes (Radosevich et al, 1996). Vale ressaltar que é na região de solo próximo ao caule da planta, até 0,30 m de profundidade, que a maior parte do sistema radicular do cafeeiro (Alfonsi et al, 2005;DaMatta et al, 2009) se concentra, indicando que a ocorrência de plantas daninhas nessa região do solo é de fato indesejável e danosa ao cafeeiro. Felizmente, à medida que a idade do cafeeiro aumenta após o transplantio, as mudas tornam-se aparentemente mais tolerantes à competição com as plantas daninhas (Fialho et al, 2010).…”

“…Para essas aná-lises, adotaram-se os procedimentos descritos em Ronchi & Silva (2004). Ainda nessas duas épocas, no dia da aplicação dos herbicidas, fezse a caracterização da área foliar média das plantas, por metodologia não destrutiva descrita por Antunes et al (2008). Na época 3, no dia da aplicação dos tratamentos e também aos 105 DAT, foram medidos: a altura de plantas, o diâmetro do caule e o comprimento, número de nós, número de folhas e área foliar total de dois ramos plagiotrópicos (por parcela) do terço médio do cafeeiro.…”