Non-destructive measurement of leaf area and leaf pigments in feijoa trees/Metodo nao-destrutivo para estimar area foliar e pigmentos foliares em feijoa

Leaf area ([cm.sup.2] per leaf) and leaf pigment content are important traits that can be used to better understand a plants physiology. In this study, empirical non-destructive models for leaf area and leaf pigment based on the leaf dimensions, length (L) and width (W) in centimeters, and chlorophyll meter readings were developed for feijoa (Acca sellowiana). The experiment was carried out during January 2016 using five-year-old trees of 60 genotypes, grown under field conditions in the state of Parana, Brazil. The proposed leaf area (LA) model was LA = 0.0022 [L.sup.3] + 0.1482 [W.sup.2] + 0.6159 LW + 0.1076 ([R.sup.2] = 0.99). Three current leaf area models found in the literature were also assessed. All of the already created models were less accurate than the model proposed in this article. The proposed leaf pigment models were based on the Falker Chlorophyll Index for Chlorophyll a (A) and b (B), these were [Chl.sub.a] = 2.564 A + 13.098 B--42.605 ([R.sup.2] = 0.94), [Chl.sub.b] = 1.538 A + 3.287 B + 8.847 ([R.sup.2] = 0.86) and Carotenoids = 0.947 B + 8.943 ([R.sup.2] = 0.88) expressed as [micro]mol [m.sup.-2] of leaf blade. In conclusion, the proposed models in this study were shown to be a reliable non-destructivel way of estimating A. sellowiana leaf area and leaf pigment. Key words: indirect estimates, pineapple guava, Acca sellowiana A area foliar ([cm.sup.2] por folha) e o conteudo de pigmentos foliares sao importantes caracteristicas usadas para melhor entender a fisiologia das plantas. Neste estudo, modelos nao-destrutivos para area foliar e conteudo de pigmentos baseados no comprimento (L) e na largura (W) da folha, e na leitura do teor de clorofila, foram desenvolvidos para feijoa (Acca sellowiana). O experimento foi desenvolvido durante o mes de janeiro de 2016 usando 60 genotipos com cinco anos de idade, cultivados no estado do Parana, Brasil. A proposta de modelo para area foliar (LA) foi LA = 0,0022 [L.sup.3] + 0,1482 [W.sup.2] + 0,6159 LW + 0,1076 ([R.sup.2] = 0,99). Tres modelos encontrados na literatura tambem foram analisados. Todos esses modelos tiveram menor acuracia que o modelo proposto por este estudo. Os modelos propostos para estimar os pigmentos foliares foram baseados no Falker Chlorophyll Index para clorofila a (A) and b (B), sendo estes [Chl.sub.a] = 2,564 A + 13,098 B--42,605 ([R.sup.2] = 0,94), [Chl.sub.b] = 1,538 A + 3,287 B + 8,847 ([R.sup.2] = 0,86) e carotenoides = 0,947 B + 8,943 ([R.sup.2] = 0,88) expressos como