Validação das unidades arbitrárias do teor de clorofilas obtido em folhas intactas de seringueira.

Abstract

Resumo -A determinação do conteúdo de clorofilas foliares é uma característica de interesse dos ecofisiologistas e dos produtores rurais. Com vistas à utilização prática e nas publicações científicas, objetivou-se com o presente trabalho estabelecer, para folhas de seringueira, equações capazes de converter para o sistema internacional as unidades arbitrárias que expressam os teores de clorofila a (Chl a ), clorofila b (Chl b ) e clorofila total (Chl tot ) obtidos em folhas intactas com uso de clorofilômetro portátil. Folhas em diferentes posições da planta e diferentes estádios de maturação, representativas de um grande intervalo de concentração de pigmentos, foram coletadas e analisadas em campo com uso do ClorofiLOG Falker ®, através de quatro avaliações em 45 folíolos medianos. Estes foram posteriormente processados em laboratório para a obtenção do extrato de pigmentos com uso de dimetilsulfóxido (DMSO) por incubação em banho-maria, dosagem em espectrofotômetro de absorção molecular e conversão em teor de pigmentos por unidade de massa fresca, com uso de equações convencionais. Os dados foram avaliados quanto ao coeficiente de correlação de Pearson e testados diferentes modelos de regressão. Para todas as variáveis, o ajuste linear é o mais adequado, com coeficientes de correlação das equações de ajuste (r) de 0,74 para Chl b e 0,88 para Chl a e Chl tot .Palavras-chave -Ajuste linear. ClorofiLOG Falker. Dimetilsulfóxido. Hevea brasiliensis. Abstract -The determination of foliar chlorophyll content is a characteristic that interests ecophysiologists and rural producers.With consideration for practical uses as well as scientific publications, our present work aims to establish equations, for rubber tree leaves, that can convert arbitrary units of expressing chlorophyll content to the international system. Chlorophyll a (Chla), chlorophyll b (Chlb), and total chlorophyll (Chltot) were obtained from intact leaves using a portable chlorophyll detecting instrument. Leaves from different positions on the plant, at various stages of maturity, and representing a large spectrum of pigment concentrations, were collected and analyzed in the field using the Clorofil OG Falkner ® instrument, through four evaluations in forty-five medium leaflets. At the laboratory, leaflets underwent a process of pigment extraction. They were incubated in a water-bath with dimethylsulfoxide (DMSO), dosed in molecular absorption spectrophotometer, and converted into pigment content per unit of fresh weight using conventional equations. The data were evaluated according to the Pearson correlation coefficient and tested with different regression models. For all variables, the linear fit is the most adequate, with correlation coefficients (r) 0.74 for Chlb and 0.88 for Chla and Chltot t .

Non-destructive measurement of leaf area and leaf pigments in feijoa trees

“…Models for chlorophyll and carotenoids (µmol m -2 ) contents in Acca sellowiana leaves and their respective adjusted coefficient of determination (R 2 ), mean absolute error (MAE) and concordance correlation coefficient (CCC) according to the The Clorofilog-1030 device is patented and has been commercially available since 2008. Since then, LP content estimation from FCI readings has been applied for Cotton plants -Gossypium hirsutum (Brito et al, 2011), Castor oil plant -Ricinus communis (Rigon et al, 2012b), Sesame -Sesamum indicum (Rigon et al, 2012a), Jatropha -Jatropha curcas (Rigon et al, 2013), Rubber tree -Hevea brasiliensis (Conforto et al, 2014), Italian ryegrass -Lolium multiflorum (Kaspary et al, 2014), and six Brazilian Atlantic Forest native trees (Vieira Silva, 2014).…”

“…LP models of the species listed above were related to FCI a+b, except in Conforto et al (2014) and Vieira Silva (2014), who used individual FCI a, FCI b and FCI a+b readings. In the present study, the modeling was based on FCIa and FCIb combined into the same model, as was observed in Wellburn (1994), who used equations that included both absorbance readings to estimate Chl content, since there is mutual interference between the two Chl wavelengths.…”

“…One of the most frequently used indirect methods for estimating LA are mathematical models involving leaf length and/or leaf width (Peksen, 2007). While LP content can be related to chlorophyll meter readings using a portable Clorofilog-1030 (Brito et al, 2011;Rigon et al, 2012a, b;Conforto et al, 2014;Kaspary et al, 2014). For LA, the mathematical models are species-specific (Demirsoy, 2009), although they can also vary among cultivars (Buttaro et al, 2015).…”