Melhoria das medições indiretas do índice de área foliar com uso da altura do dossel

pab Pesquisa Agropecuária Brasileira Pesq. agropec. bras. 0100-204X 1678-3921 Embrapa Secretaria de Pesquisa e Desenvolvimento; Pesquisa Agropecuária Brasileira Resumo: O objetivo deste trabalho foi avaliar o uso da altura do dossel da planta como variável de ajuste para melhorar as medições indiretas do índice de área foliar (IAF). Três experimentos foram conduzidos com diferentes culturas - milho (Zea mays), soja (Glycine max) e cana-de-açúcar (Saccharum officinarum) -, para comparar o desempenho do IAF medido indiretamente (IAFind) e corrigido pela variável de ajuste com o IAF medido diretamente (IAFref). Sem a correção proposta, o IAFind tendeu a ser superestimado em 20%, em média, em relação ao IAFref, para as três culturas. Após o uso da altura da colheita para ajustar o IAFind, observaram-se fortes relações positivas entre o IAFref e o IAFind corrigido (R2 = 0,96); a superestimação foi reduzida para 4% e o erro médio quadrático diminuiu para 0,35 m2 m-2. A variável altura do dossel mostra-se promissora para correção do IAF das culturas de soja, milho e cana-de-açúcar. Introduction The leaf area index (LAI) is defined as the ratio of the total leaf area per unit area exploited by the crop (Miller, 1967) and is a key variable in a range of processes including gas and energy exchange, water and nutrient cycling, canopy health, and primary production (Fang et al., 2018; Yan et al., 2019). It can be evaluated by: direct methods, such as planimeters, area integrators, and specific relationships (Chianucci & Cutini, 2013); and indirect methods, as dry mass and electronic devices to assess the light intercepted by the canopies (Gonsamo et al., 2018; Fang et al., 2019). An accurate quantification of the LAI is, therefore, important for crop growth and development (Addai & Alimiyawo, 2015). Several commercial instruments may be used for the indirect measurement of the LAI, including the Accupar LP-80 Ceptometer (Meter Group, Inc., Pullman, WA, USA), LAI-2200C Plant Canopy Analyzer (LI-COR, Inc., Lincoln, NE, USA), SunScan Canopy Analysis System (Delta-T Devices Ltd, Cambridge, United Kingdom), and Demon (CSIROpedia, Canberra, Australia) (Adeboye et al., 2019). Of these optical instruments, the LAI-2200C Plant Canopy Analyzer and its predecessor, the LAI-2000, are among the most used worldwide (Kobayashi et al., 2013; LI-COR, Inc., 2015), and their algorithms are based on the approaches proposed by Miller (1986). In the case of the LAI-2000 analyzer, the manufacturer alerts that there may be divergences in LAI estimates when the plants have a large amount of dead and/or senescent material and recommends that calibrations be made using direct LAI determinations to improve the results (Sbrissia & Silva, 2008). Electronic analyzers based on gap fraction or transmittance have been widely used to evaluate crops such as corn (Zea mays L.) (Ariza-Carricondo et al., 2019), sugarcane (Saccharum officinarum L.) (Lisboa et al., 2018), acid lime [Citrus latifolia (Yu.Tanaka) Tanaka] (Coelho Filho et al., 2012), and soybean [Glycine max (L.) Merr.] (Malone et al., 2002; Pierozan Junior & Kawakami, 2013; Mbangiwa et al., 2019), as well as isolated plants of jatropha (Jatropha curcas L.) (Lena et al., 2016) and eucalyptus (Eucalyptus urophylla x grandis) plantations (Giunti Neto et al., 2015). However, in all these studies, the authors reported the need for calibration to improve the quality of the data gathered with those devices, but did not consider canopy height as an auxiliary variable. Although indirect methods to estimate the LAI have already been compared in previous researches, large uncertainties still remain and the use of multiple instruments has revealed a considerable variability and uncertainty in the taken measurements (Ariza-Carricondo et al., 2019). In some cases, it is recommended to combine the LAI-2000 instrument with another method for the correct estimation of the LAI (Ryu et al., 2010a, 2010b). The objective of this work was to evaluate the use of plant height as a calibration variable for improving indirect measurements of the leaf area index. Materials and Methods Three experiments were carried out with the corn, soybean, and sugarcane crops in the experimental area of Escola Superior de Agricultura Luiz de Queiroz of Universidade de São Paulo (22°41'53"S, 47°38'35"W, at 538 m above sea level). The climate, according to Köppen, is Cwa, described as humid subtropical with a rainy summer and a dry winter (Marin et al., 2019). All experiments were irrigated using center-pivot i-Wob UP3 sprinklers (Senninger Irrigation, Clermont, FL, USA), managed by a crop water balance based on data acquired from an automatic agrometeorological station installed in the same experimental area, in order to assure the maximum evapotranspiration rates for all the crops. Each experiment was conducted under conditions to guarantee potential yield (Ittersum et al., 2013; Fischer, 2015), without biotic or abiotic stresses (Fritsche-Neto & Borém, 2012), and preventive actions were taken against pests and diseases. The soils were classified as Oxisols (Peters et al., 2014) in the soybean and sugarcane crop sites and as a Chromic Acrisol Nitisol (Sobenko et al., 2019) in the corn crop site. The biometric data samples consisted of: leaf length and height for corn; dry green leaf mass for sugarcane; and direct and indirect LAI determinations and canopy height measurements for all crops. The period of experimental data collection, number of observations, and a summary of the meteorological conditions are presented in Table 1. Table 1. Period and number of leaf area index (LAI) observations, as well as a summary of the meteorological conditions during the experiment. Dataset Period of LAI observations (mm/dd/yy) Number of LAI observations Air temperature (°C) Global solar radiation (MJ) Rainfall (mm) ETo(1) (mm) Corn (Zea mays) 5/23/16 to 9/29/16 7 18.67±3.00 14.45±5.38 268.7 313.2±1.09 Soybean (Glycine max) 11/7/16 to 2/8/17 5 23.75±1.90 21.08± 6.28 696.5 354.0±1.39 Sugarcane (Saccharum officinarum) 10/4/18 to 6/19/19 13 23.28±2.77 18.80±6.19 1067.3 871.8±1.41 (1)Reference evapotranspiration obtained by the FAO-56 Penman-Monteith method (Allen et al., 1998). The P-4285YH corn hybrid was sown on 5/16/2016 and harvested on 9/29/2016. The experimental design was randomized complete blocks with four replicates. Each replicate consisted of 96-m2 plots, 3.2 m wide (four rows spaced at 0.8 m) and 30 m long (288 m2 per hybrid), resulting in a population of 60,000 plants per hectare. For fertilization, 30 kg ha-1 nitrogen, 90 kg ha-1 P2O5, and 50 kg ha-1 K2O were applied, as well as 80 kg ha-1 nitrogen topdressed. The biometric data samples were taken on 7/11/2016, 7/18/2016, 8/18/2016, 8/25/2016, 8/30/2016, and 9/22/2016. The experiment with the soybean crop consisted of a 3.0-ha field cultivated with the BRS399 RR cultivar from October 2016 to March 2017, at a row spacing of 0.45 m and with 18 seeds per linear meter, resulting in a plant density of 35.5 plants per square meter. The experimental design was randomized complete blocks with four replicates. Fertilization was performed by applying 196 kg ha-1 single superphosphate (18% P2O5, 16% Ca, and 8% S). Biometric data samples were collected on 11/29/2016, 12/5/2016, 12/28/2016, 1/5/2017, and 2/14/2017. The RB867515 sugarcane variety was planted on 5/10/2018, using nearly 9.7 buds per square meter, at a row spacing of 1.4 m. The experimental design was randomized complete blocks with four replicates. From the end of August to the beginning of October 2018, the soil was prepared and received 500 kg ha-1 reactive natural phosphate. Fertilization at planting consisted of 50 kg ha-1 N, 75 kg ha-1 P2O5, and 75 kg ha-1 K2O enriched with 0.3% B and 0.5% Zn. Two cover fertilizations were performed: the first in January 2019, with 177 kg ha-1 N as urea and 186 kg ha-1 K as potassium oxide (K2O); and the second in July 2019, with 127.5 kg ha-1 N as urea. The biometric samples were taken on 1/23/2019, 2/8/2019, 2/21/2019, 3/9/2019, 3/21/2019, 4/4/2019, 4/15/2019, 4/23/2019, 5/8/2019, 5/23/2019, 6/5/2019, 6/10/2019, and 6/19/2019. The samples used for the LAI measured directly (LAIref) and indirectly (LAIind) were collected on the same dates as those for biometrics. For the soybean crop, the LAIref was estimated with the aid of the Quant scanning and processing software, version 1.0.2 (Richter et al., 2014), used to calculate leaf area. For the corn crop, the LAIref (Vieira Junior et al., 2006) was based on measuring the width and length of green leaves, multiplied by a shape correction factor of 0.7 (Marin et al., 2005). For the sugarcane crop, the LAIref was obtained by the leaf disk method (Pierozan Junior & Kawakami, 2013). For the corn and soybean crops, 5 sample plants were randomly selected among the blocks, totalizing 20 plants, for LAIref determinations. For the soybean and sugarcane crops, 5 sample plants - 20 and 25 in total, respectively - were collected among the blocks to determine the LAIref by the destructive method. For the indirect measurements of the LAIind, the LAI-2200C electronic analyzer (LI-COR, Inc., Lincoln, NE, USA), with an embedded algorithm, was used; the theoretical background of this device is fully described in Kuusk (2016). Following the manufacturer’s recommendations (LI-COR, Inc., 2015), all LAI measurements were taken in the late afternoon or at sunrise to avoid the incidence of direct sunlight, at a 45° angle view. It should be noted that, although not performed in this work, measurements under open-sky conditions are also allowed (Pearse et al., 2016). Besides each LAIind, crop canopy height was measured using a ruler. In theory, electronic retrievers work based on notions of probability, that is, the LAI-2200C analyzer measures the probability (PΘ) that radiation will not be intercepted by the canopy, through the following equation (Ryu et al., 2010a; LI-COR, Inc., 2015): ( Θ ) = e ( − G ( Θ ) μ S ( Θ ) ) where G (Θ) is the foliage projection fraction, μ is leaf density, and S (Θ) is the distance from the top of the canopy to soil surface. S (Θ) is, therefore, a relationship between canopy height and the cosine of the angle defined between the canopy projection line and its normal (Jones, 2013). The LAIind data were statistically compared with those obtained for the LAIref and canopy height, using as agreement measures: Nash & Sutcliffe’s modeling efficiency (Ritter & Muñoz-Carpena, 2013), the correlation index, the root mean square error (RMSE), and Wilmott’s index of agreement (Willmott et al., 2012). Results and Discussion The LAIind was overestimated by about 20% compared with the LAIref for soybean, corn, and sugarcane (Figure 1), but it expressed well the time variation of the LAI for the three crops (Table 2). Based on a theoretical model and on the gap fraction measurements from 41 sites, Kobayashi et al. (2013) reported that the effective LAI must be quantified using a second approach and that, in some cases, the LAI is overestimated up to 30% at the studied sites. Particularly for the soybean crop, the LAI-2200C analyzer was not able to estimate satisfactorily the LAI at the end-of-cycle sampling (71 days after sowing), as found by Jesus et al. (2001). As in the study of Malone et al. (2002), the results probably indicate that the estimates of LAIs with defoliation below 2.0 were likely skewed by a greater proportion of pods, stems and petioles, resulting in higher values than those obtained for the directly measured LAI. Similar results were found by Liu et al. (2008) for soybean crops, since the indirect measurement overestimated the LAI by 12.5% at 96 days after sowing. However, the LAIref values are consistent with those reported by Heiffig et al. (2006) for the soybean crop, by Ferreira Junior et al. (2014) and Ariza-Carricondo et al. (2019) for corn, and by Oliveira et al. (2004) for sugarcane. Likewise, the result of the present study is in agreement with that of Liu & Pattey (2010), possibly since LAI-2000 also captures other canopy tissues from below the canopy. Figure 1. Leaf area index (LAI) measured directly (LAIref) and indirectly (LAIind) throughout the experiments for the: A, soybean (Glycine max); B, corn (Zea mays); and C, sugarcane (Saccharum officinarum) crops. Open and solid triangles represent LAIref and LAIind, respectively. The LAIref and LAIind were measured by the destructive method and with the LAI-2200C analyzer (LI-COR, Inc., Lincoln, NE, USA), respectively. Table 2. Leaf area index measured directly (LAIref) and indirectly (LAIind)(1) and canopy height of the soybean (Glycine max), corn (Zea mays), and sugarcane (Saccharum officinarum) crops during the experiment. DAS or DAE or DAP(2) LAIind LAIref Canopy height (m) Soybean 22 2.0 1.3 0.19 29 3.6 2.3 0.20 50 6.3 4.9 0.65 59 6.7 5.6 0.77 71 3.6 0.6 0.84 Mean 4.5 3.0 0.53 Corn 56 1.3 0.6 0.29 63 1.6 0.8 0.43 94 3.1 2.7 1.32 101 3.2 2.9 1.32 106 3.2 2.9 1.45 129 2.7 2.6 1.63 Mean 2.5 2.1 1.07 Sugarcane 110 2.4 1.3 1.38 126 1.9 1.1 1.50 139 2.5 1.6 2.11 155 3.1 2.0 2.45 167 6.3 4.9 2.67 181 6.4 5.1 2.75 192 5.1 4.5 3.07 200 4.8 4.4 2.80 215 5.2 4.6 3.14 230 4.9 4.1 3.63 243 4.7 4.2 3.39 248 5.1 4.3 3.55 257 4.4 3.3 3.27 Mean 4.4 3.5 2.75 (1)Measured indirectly with the LAI-2200C analyzer (LI-COR, Inc., Lincoln, NE, USA) and directly by the destructive method. (2)DAS, days after sowing in soybean; DAE, days after emergence in corn; and DAP, days after planting in sugarcane. The LAIind (Figure 2 A), compared with the LAIref, showed good accuracy for all three crops evaluated, as observed by Welles & Norman (1991) and Jonckheere et al. (2004) when using the LAI-2000 analyzer to estimate the LAI in homogeneous canopies such as those of soybean, wheat (Triticum aestivum L.), and grass. This is probably related to the fact that, although they are not the same devices, the successors of LAI-2000 use the same theoretical background, with some improvements (Yan et al., 2019). The obtained coefficient of determination (R2) ranged from 0.46 to 0.88, with higher values for sugarcane and corn and a lower precision for soybean (Table 3). The lower R2 value for the soybean crop may be explained by the gap fraction highly sensitive to canopy structure, leaf distribution, and leaf plasticity (López-Lozano et al., 2007). Figure 2. Scatter plot of the leaf area index measured directly (LAIref) and indirectly (LAIind) throughout the experiments for the soybean (Glycine max), corn (Zea mays), and sugarcane (Saccharum officinarum) crops (A) and scatter plot of the leaf area index corrected by canopy height (B). The LAIref and LAIind were measured by the destructive method and with the LAI-2200C analyzer (LI-COR, Inc., Lincoln, NE, USA), respectively. Table 3. Comparison between statistical tests and modeling performance with and without canopy height (H) for the correction of the leaf area index (LAI) for the soybean (Glycine max), corn (Zea mays), and sugarcane (Saccharum officinarum) crops. Statistical indicator(1) LAIref x LAIind(2) LAIref x [LAIind x H] Soybean R2 0.46 0.95 RMSE 2.87 0.19 d 0.60 0.89 NS 0.12 0.95 Corn R2 0.72 0.99 RMSE 1.55 0.03 d 0.76 0.97 NS 0.58 0.95 Sugarcane R2 0.88 0.96 RMSE 11.14 0.84 d 0.65 0.97 NS 0.56 0.96 (1)R2, coefficient of determination; RMSE, root mean square error; d, Willmott’s index of agreement; and NS, Nash-Sutcliffe’s index of agreement. (2)LAIref, LAI obtained directly by the destructive method; and LAIind, LAI obtained indirectly with the LAI-2200C analyzer (LI-COR, Inc., Lincoln, NE, USA). Although Willmott’s index of agreement showed satisfactory efficiency, a way to improve the correlation between the LAIref and LAIind data was still sought. In addition, the canopy height values obtained for the studied crops were considered consistent with those found by Doná et al. (2019), Shioga et al. (2015), and Oliveira et al. (2010) for similar soybean, corn, and sugarcane cultivars, respectively (Table 2); the observed peaks tended to coincide with the maximum LAI values. After canopy height was used as a calibration variable, R2 and Willmott’s index of agreement showed better performance (Figure 2 B). R2 ranged from 0.95 to 0.99, and RMSE decreased considerably from 11.14 to 0.84 for sugarcane. In this way, there was a positive contribution to improving estimation, and all p-values were <0.01, except the one for soybean (Table 4). Galzerano et al. (2012) and Coêlho et al. (2014) also found a good correlation between canopy height and determinations of the LAI; however, these authors evaluated tropical grasses. Table 4. Linear regression coefficients between the leaf area index measured directly (LAIref) and indirectly (LAIind)(1) and canopy height (H), as input variables, for the soybean (Glycine max), corn (Zea mays), and sugarcane (Saccharum officinarum) crops throughout the experiments. Variables Coefficient P-value Soybean Intersection -1.2662413 0.271 LAIind 1.30994127 0.027 H -0.030408 0.167 Corn Intersection -0.8797169 0.014 LAIind 0.94336531 0.006 H 0.00541574 0.077 Sugarcane Intersection -1.1741805 0.005 LAIind 0.87195609 <0.01 H 0.00311855 0.090 (1)Measured directly by the destructive method and indirectly with the LAI-2200C analyzer (LI-COR, Inc., Lincoln, NE, USA). Inserting canopy height as a secondary input variable in regression reduced the error of both Willmott’s index of agreement and R2; therefore, the variable contributed positively to the accuracy of the used method (Table 3). Although canopy height improved the verified correlation, it is possible that other factors influence LAI-2200C measurements, mainly in the crop reproductive stage due to a logical relationship, which implies that other plant structures, such as stems and pods, are considered as leaf area (Malone et al., 2002). This process seems to have occurred for the soybean cultivar evaluated in the present work (Figure 2 B). Welles & Norman (1991) reported another source of uncertainty in the theory behind analyzers, highlighting that the electronic indirect method fails to distinguish senescent or dead tissue from living tissue, increasing the discrepancy in the LAI readings, as in the case of the soybean crop. To improve measurements, Nilson (1971) suggests relating clumping to the size of vegetative elements and to the distance between them. Kucharik et al. (1998) compared the variation of this parameter in a homogeneous canopy and found that the LAI, under these conditions, only varies as a function of canopy height. Canopy height proves to be a promising calibration variable for use in the corn and sugarcane crops. One of the reasons is that, since the LAI can be determined throughout the crop cycle by indirect measurements, more reliable data can be obtained. In both crops, correcting by canopy height resulted in a more accurate LAI because these plants have a higher proportion of leaves than other structures, when compared with soybean (Argenta et al., 2001). Conclusions The values of the leaf area index (LAI) estimated by the LAI-2200C electronic device are overestimated for the soybean (Glycine max), corn (Zea mays), and sugarcane (Saccharum officinarum) crops. Canopy height as a calibration variable can correct indirect LAI measurements and improve agreement with direct LAI measurements. Acknowledgments To Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), for grants (process numbers 301424/2015-2, 401662/2016-0, and 425174/2018-2); to Fundação de Amparo à Pesquisa do Estado de São Paulo (Fapesp), for grants (process numbers 2017/20925-0 and 2017/50445-0); and to Empresa Brasileira de Pesquisa Agropecuária (Embrapa) and to Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Capes), for support. References ADDAI, I.K.; ALIMIYAWO, M. Graphical determination of leaf area index and its relationship with growth and yield parameters of sorghum (Sorghum bicolor L. Moench) as affected by fertilizer application. Journal of Agronomy, v.14, p.272-278, 2015. DOI: https://doi.org/10.3923/ja.2015.272.278. ADDAI I.K. ALIMIYAWO M. Graphical determination of leaf area index and its relationship with growth and yield parameters of sorghum (Sorghum bicolor L. Moench) as affected by fertilizer application Journal of Agronomy 14 272 278 2015 10.3923/ja.2015.272.278 ADEBOYE, O.B.; ADEBOYE, A.P.; ANDERO, O.S.; FALANA, O.B. Evaluation of AccuPAR LP 80 in estimating leaf area index of soybeans canopy in Ile-Ife, Nigeria. Agricultural Research, v.8, p.297-308, 2019. DOI: https://doi.org/10.1007/s40003-018-0371-1. ADEBOYE O.B. ADEBOYE A.P. ANDERO O.S. FALANA O.B. Evaluation of AccuPAR LP 80 in estimating leaf area index of soybeans canopy in Ile-Ife, Nigeria Agricultural Research 8 297 308 2019 10.1007/s40003-018-0371-1 ALLEN, R.G.; PEREIRA, L.S.; RAES, D.; SMITH, M. Crop evapotranspiration: guidelines for computing crop requirements. Rome: FAO, 1998. (FAO Irrigation and Drainage Paper, 56). DOI: https://doi.org/10.1016/j.eja.2010.12.001. ALLEN R.G. PEREIRA L.S. RAES D. SMITH M. Crop evapotranspiration: guidelines for computing crop requirements Rome FAO 1998 FAO Irrigation and Drainage Paper, 56 10.1016/j.eja.2010.12.001 ARGENTA, G.; SILVA, P.R.F. da; SANGOI, L. Arranjo de plantas em milho: análise do estado-da-arte. Ciência Rural, v.31, p.1075-1084, 2001. DOI: https://doi.org/10.1590/S0103-84782001000600027. ARGENTA G. SILVA P.R.F. da SANGOI L. Arranjo de plantas em milho: análise do estado-da-arte Ciência Rural 31 1075 1084 2001 10.1590/S0103-84782001000600027 ARIZA-CARRICONDO, C.; MAURO, F. DI; BEECK, M.O. de; ROLAND, M.; GIELEN, B.; VITALE, D.; CEULEMANS, R.; PAPALE, D. A comparison of different methods for assessing leaf area index in four canopy types. Central European Forestry Journal, v.65, p.67-80, 2019. DOI: https://doi.org/10.2478/forj-2019-0011. ARIZA-CARRICONDO C. MAURO F. DI BEECK M.O. de ROLAND M. GIELEN B. VITALE D. CEULEMANS R. PAPALE D. A comparison of different methods for assessing leaf area index in four canopy types Central European Forestry Journal 65 67 80 2019 10.2478/forj-2019-0011 CHIANUCCI, F.; CUTINI, A. Estimation of canopy properties in deciduous forests with digital hemispherical and cover photography. Agricultural and Forest Meteorology, v.168, p.130-139, 2013. DOI: https://doi.org/10.1016/j.agrformet.2012.09.002. CHIANUCCI F. CUTINI A. Estimation of canopy properties in deciduous forests with digital hemispherical and cover photography Agricultural and Forest Meteorology 168 130 139 2013 10.1016/j.agrformet.2012.09.002 COELHO FILHO, M.A.; VILLA-NOVA, N.A.; ANGELOCCI, L.R.; MARIN, F.R.; RIGHI, C.A. Método para estimativa do IAF de árvores isoladas ou de plantações com dossel fechado. Revista Brasileira de Engenharia Agrícola e Ambiental, v.16, p.529-538, 2012. DOI: https://doi.org/10.1590/S1415-43662012000500009. COELHO M.A. FILHO VILLA-NOVA N.A. ANGELOCCI L.R. MARIN F.R. RIGHI C.A. Método para estimativa do IAF de árvores isoladas ou de plantações com dossel fechado Revista Brasileira de Engenharia Agrícola e Ambiental 16 529 538 2012 10.1590/S1415-43662012000500009 COÊLHO, J.J.; DUBEUX JR, J.C.B.; SANTOS, E.R.S.; LEÃO NETO, J.M.C.; CUNHA, M.V. da; SANTOS, M.V.F. dos; MELLO, A.C.L. de; LIRA, M. de A. Canopy height and its relationship with leaf area index and light interception in tropical grasses. Tropical Grasslands - Forrajes Tropicales, v.2, p.31-32, 2014. DOI: https://doi.org/10.17138/TGFT(2)31-32. COÊLHO J.J. DUBEUX JR J.C.B. SANTOS E.R.S. LEÃO J.M.C. NETO CUNHA M.V. da SANTOS M.V.F. dos MELLO A.C.L. de LIRA M. de A. Canopy height and its relationship with leaf area index and light interception in tropical grasses Tropical Grasslands - Forrajes Tropicales 2 31 32 2014 10.17138/TGFT(2)31-32 DONÁ, S.; KANTHACK, R.A.D.; CAÇÃO, M.M. de F.R.; SANTOS, G.X.L. dos; CORDEIRO-JUNIOR, P.S.; NAKAYAMA, F.T.; FINOTO, E.L.; LEÃO, P.C. da L. Desempenho agronômico de cultivares de soja no Vale do Paranapanema, Safras 2017/18 e 2018/19. Nucleus, p.63-76, 2019. Edição especial. DOI: https://doi.org/10.3738/1982.2278.3626. DONÁ S. KANTHACK R.A.D. CAÇÃO M.M. de F.R. SANTOS G.X.L. dos CORDEIRO-JUNIOR P.S. NAKAYAMA F.T. FINOTO E.L. LEÃO P.C. da L. Desempenho agronômico de cultivares de soja no Vale do Paranapanema, Safras 2017/18 e 2018/19 Nucleus 63 76 2019 Edição especial 10.3738/1982.2278.3626 FANG, H.; BARET, F.; PLUMMER, S.; SCHAEPMAN-STRUB, G. An overview of global leaf area index (LAI): methods, products, validation, and applications. Reviews of Geophysics, v.57, p.739-799, 2019. DOI: https://doi.org/10.1029/2018RG000608. FANG H. BARET F. PLUMMER S. SCHAEPMAN-STRUB G. An overview of global leaf area index (LAI): methods, products, validation, and applications Reviews of Geophysics 57 739 799 2019 10.1029/2018RG000608 FANG, H.; YE, Y.; LIU, W.; WEI, S.; MA, L. Continuous estimation of canopy leaf area index (LAI) and clumping index over broadleaf crop fields: an investigation of the PASTIS-57 instrument and smartphone applications. Agricultural and Forest Meteorology, v.253-254, p.48-61, 2018. DOI: https://doi.org/10.1016/J.AGRFORMET.2018.02.003. FANG H. YE Y. LIU W. WEI S. MA L. Continuous estimation of canopy leaf area index (LAI) and clumping index over broadleaf crop fields: an investigation of the PASTIS-57 instrument and smartphone applications Agricultural and Forest Meteorology 253-254 48 61 2018 10.1016/J.AGRFORMET.2018.02.003 FERREIRA JUNIOR, R.A.; SOUZA, J.L. de; TEODORO, I.; LYRA, G.B.; SOUZA, R.C. de; ARAÚJO NETO, R.A. de. Eficiência do uso da radiação em cultivos de milho em Alagoas. Revista Brasileira de Engenharia Agrícola e Ambiental, v.18, p.322-328, 2014. DOI: https://doi.org/10.1590/S1415-43662014000300012. FERREIRA R.A. JUNIOR SOUZA J.L. de TEODORO I. LYRA G.B. SOUZA R.C. de ARAÚJO R.A. de. NETO Eficiência do uso da radiação em cultivos de milho em Alagoas Revista Brasileira de Engenharia Agrícola e Ambiental 18 322 328 2014 10.1590/S1415-43662014000300012 FISCHER, R.A. Definitions and determination of crop yield, yield gaps, and of rates of change. Field Crops Research, v.182, p.9-18, 2015. DOI: https://doi.org/10.1016/j.fcr.2014.12.006. FISCHER R.A. Definitions and determination of crop yield, yield gaps, and of rates of change Field Crops Research 182 9 18 2015 10.1016/j.fcr.2014.12.006 FRITSCHE-NETO, R.; BORÉM, A. (Ed.). Plant breeding for biotic stress resistance. Heidelberg: Springer, 2012. DOI: https://doi.org/10.1007/978-3-642-33087-2. FRITSCHE-NETO R. BORÉM A. Plant breeding for biotic stress resistance Heidelberg Springer 2012 10.1007/978-3-642-33087-2 GALZERANO, L.; MALHEIROS, E.B.; MORGADO, E. da S.; RUGGIERI, A.C. Interceptação de luz e índice de área foliar em relação a altura do dossel de gramíneas forrageiras. Nucleus Animalium, v.4, p.11-18, 2012. DOI: https://doi.org/10.3738/NA.V4I2.742. GALZERANO L. MALHEIROS E.B. MORGADO E. da S. RUGGIERI A.C. Interceptação de luz e índice de área foliar em relação a altura do dossel de gramíneas forrageiras Nucleus Animalium 4 11 18 2012 10.3738/NA.V4I2.742 GIUNTI NETO, C.J.; HAKAMADA, R.E.; OTTO, M.S.G.; SILVA, S.R.; STAPE, J.L. Calibração de dois métodos indiretos para estimativa do índice de área foliar em plantações de Eucalyptus. Scientia Forestalis, v.43, p.919-930, 2015. DOI: https://doi.org/10.18671/scifor.v43n108.16. GIUNTI C.J. NETO HAKAMADA R.E. OTTO M.S.G. SILVA S.R. STAPE J.L. Calibração de dois métodos indiretos para estimativa do índice de área foliar em plantações de Eucalyptus Scientia Forestalis 43 919 930 2015 10.18671/scifor.v43n108.16 GONSAMO, A.; WALTER, J.-M.; CHEN, J.M.; PELLIKKA, P.; SCHLEPPI, P. A robust leaf area index algorithm accounting for the expected errors in gap fraction observations. Agricultural and Forest Meteorology, v.248, p.197-204, 2018. DOI: https://doi.org/10.1016/J.AGRFORMET.2017.09.024. GONSAMO A. WALTER J.-M. CHEN J.M. PELLIKKA P. SCHLEPPI P. A robust leaf area index algorithm accounting for the expected errors in gap fraction observations Agricultural and Forest Meteorology 248 197 204 2018 10.1016/J.AGRFORMET.2017.09.024 HEIFFIG, L.S.; CÂMARA, G.M. de S.; MARQUES, L.A.; PEDROSO, D.B.; PIEDADE, S.M. de S. Fechamento e índice de área foliar da cultura da soja em diferentes arranjos espaciais. Bragantia, v.65, p.285-295, 2006. DOI: https://doi.org/10.1590/S0006-87052006000200010. HEIFFIG L.S. CÂMARA G.M. de S. MARQUES L.A. PEDROSO D.B. PIEDADE S.M. de S. Fechamento e índice de área foliar da cultura da soja em diferentes arranjos espaciais Bragantia 65 285 295 2006 10.1590/S0006-87052006000200010 ITTERSUM, M.K. van; CASSMAN, K.G.; GRASSINI, P.; WOLF, J.; TITTONELL, P.; HOCHMAN, Z. Yield gap analysis with local to global relevance - a review. Field Crops Research, v.143, p.4-17, 2013. DOI: https://doi.org/10.1016/j.fcr.2012.09.009. ITTERSUM M.K. van CASSMAN K.G. GRASSINI P. WOLF J. TITTONELL P. HOCHMAN Z. Yield gap analysis with local to global relevance - a review Field Crops Research 143 4 17 2013 10.1016/j.fcr.2012.09.009 JESUS, W.C. de; VALE, F.X.R. do; COELHO, R.R.; COSTA, L.C. Comparison of two methods for estimating leaf area index on common bean. Agronomy Journal, v.93, p.989-991, 2001. DOI: https://doi.org/10.2134/agronj2001.935989x. JESUS W.C. de VALE F.X.R. do COELHO R.R. COSTA L.C. Comparison of two methods for estimating leaf area index on common bean Agronomy Journal 93 989 991 2001 10.2134/agronj2001.935989x JONCKHEERE, I.; FLECK, S.; NACKAERTS, K.; MUYS, B.; COPPIN, P.; WEISS, M.; BARET, F. Review of methods for in situ leaf area index determination. Part I. Theories, sensors and hemispherical photography. Agricultural and Forest Meteorology, v.121, p.19-35, 2004. DOI: https://doi.org/10.1016/j.agrformet.2003.08.027. JONCKHEERE I. FLECK S. NACKAERTS K. MUYS B. COPPIN P. WEISS M. BARET F. Review of methods for in situ leaf area index determination. Part I. Theories, sensors and hemispherical photography Agricultural and Forest Meteorology 121 19 35 2004 10.1016/j.agrformet.2003.08.027 JONES, H.G. Plants and microclimate: a quantitative approach to environmental plant physiology. 3rd ed. Cambridge: Cambridge University Press, 2013. DOI: https://doi.org/10.1017/CBO9780511845727. JONES H.G. Plants and microclimate: a quantitative approach to environmental plant physiology 3rd ed. Cambridge Cambridge University Press 2013 10.1017/CBO9780511845727 KOBAYASHI, H.; RYU, Y.; BALDOCCHI, D.D.; WELLES, J.M.; NORMAN, J.M. On the correct estimation of gap fraction: how to remove scattered radiation in gap fraction measurements? Agricultural and Forest Meteorology, v.174-175, p.170-183, 2013. DOI: https://doi.org/10.1016/J.AGRFORMET.2013.02.013. KOBAYASHI H. RYU Y. BALDOCCHI D.D. WELLES J.M. NORMAN J.M. On the correct estimation of gap fraction: how to remove scattered radiation in gap fraction measurements? Agricultural and Forest Meteorology 174-175 170 183 2013 10.1016/J.AGRFORMET.2013.02.013 KUCHARIK, C.J.; NORMAN, J.M.; GOWER, S.T. Measurements of leaf orientation, light distribution and sunlit leaf area in a boreal aspen forest. Agricultural and Forest Meteorology, v.91, p.127-148, 1998. DOI: https://doi.org/10.1016/S0168-1923(98)00058-6. KUCHARIK C.J. NORMAN J.M. GOWER S.T. Measurements of leaf orientation, light distribution and sunlit leaf area in a boreal aspen forest Agricultural and Forest Meteorology 91 127 148 1998 10.1016/S0168-1923(98)00058-6 KUUSK, A. Specular reflection in the signal of LAI-2000 plant canopy analyzer. Agricultural and Forest Meteorology, v.221, p.242-247, 2016. DOI: https://doi.org/10.1016/j.agrformet.2016.02.015. KUUSK A. Specular reflection in the signal of LAI-2000 plant canopy analyzer Agricultural and Forest Meteorology 221 242 247 2016 10.1016/j.agrformet.2016.02.015 LENA, B.P.; FOLEGATTI, M.V.; FRANCISCO, J.P.; SANTOS, O.N.A.; ANDRADE, I.P.S. Performance of LAI-2200 Plant Canopy Analyzer on leaf area index of jatropha nut estimation. Journal of Agronomy, v.15, p.191-197, 2016. DOI: https://doi.org/10.3923/ja.2016.191.197. LENA B.P. FOLEGATTI M.V. FRANCISCO J.P. SANTOS O.N.A. ANDRADE I.P.S. Performance of LAI-2200 Plant Canopy Analyzer on leaf area index of jatropha nut estimation Journal of Agronomy 15 191 197 2016 10.3923/ja.2016.191.197 LI-COR, INC. LAI-2200C Plant Canopy Analyzer: instruction manual. Lincoln, [2015]. 258p. LI-COR, INC LAI-2200C Plant Canopy Analyzer: instruction manual Lincoln 2015 258p LISBOA, I.P.; CHERUBIN, M.R.; LIMA, R.P.; CERRI, C.C.; SATIRO, L.S.; WIENHOLD, B.J.; SCHMER, M.R.; JIN, V.L.; CERRI, C.E.P. Sugarcane straw removal effects on plant growth and stalk yield. Industrial Crops and Products, v.111, p.794-806, 2018. DOI: https://doi.org/10.1016/j.indcrop.2017.11.049. LISBOA I.P. CHERUBIN M.R. LIMA R.P. CERRI C.C. SATIRO L.S. WIENHOLD B.J. SCHMER M.R. JIN V.L. CERRI C.E.P. Sugarcane straw removal effects on plant growth and stalk yield Industrial Crops and Products 111 794 806 2018 10.1016/j.indcrop.2017.11.049 LIU, G.; XIE, Y.; GAO, X.-F.; DUAN, X.-W. Application of SunScan canopy analysis system in measuring leaf area index of soybean. Chinese Journal of Ecology, v.27, p.862-866, 2008. LIU G. XIE Y. GAO X.-F. DUAN X.-W. Application of SunScan canopy analysis system in measuring leaf area index of soybean Chinese Journal of Ecology 27 862 866 2008 LIU, J.; PATTEY, E. Retrieval of leaf area index from top-of-canopy digital photography over agricultural crops. Agricultural and Forest Meteorology, v.150, p.1485-1490, 2010. DOI: https://doi.org/10.1016/j.agrformet.2010.08.002. LIU J. PATTEY E. Retrieval of leaf area index from top-of-canopy digital photography over agricultural crops Agricultural and Forest Meteorology 150 1485 1490 2010 10.1016/j.agrformet.2010.08.002 LÓPEZ-LOZANO, R.; BARET, F.; CHELLE, M.; ROCHDI, N.; ESPAÑA, M. Sensitivity of gap fraction to maize architectural characteristics based on 4D model simulations. Agricultural and Forest Meteorology, v.143, p.217-229, 2007. DOI: https://doi.org/10.1016/j.agrformet.2006.12.005. LÓPEZ-LOZANO R. BARET F. CHELLE M. ROCHDI N. ESPAÑA M. Sensitivity of gap fraction to maize architectural characteristics based on 4D model simulations Agricultural and Forest Meteorology 143 217 229 2007 10.1016/j.agrformet.2006.12.005 MALONE, S.; HERBERT, D.A.; HOLSHOUSER, D.L. Evaluation of the LAI-2000 Plant Canopy Analyzer to estimate leaf area in manually defoliated soybean. Agronomy Journal, v.94, p.1012-1019, 2002. DOI: https://doi.org/10.2134/agronj2002.1012. MALONE S. HERBERT D.A. HOLSHOUSER D.L. Evaluation of the LAI-2000 Plant Canopy Analyzer to estimate leaf area in manually defoliated soybean Agronomy Journal 94 1012 1019 2002 10.2134/agronj2002.1012 MARIN, F.R.; ANGELOCCI, L.R.; NASSIF, D.S.P.; VIANNA, M.S.; PILAU, F.G.; SILVA, E.H.F.M. da; SOBENKO, L.R.; GONÇALVES, A.O.; PEREIRA, R.A.A.; CARVALHO, K.S. Revisiting the crop coefficient - reference evapotranspiration procedure for improving irrigation management. Theoretical and Applied Climatology, v.138, p.1785-1793, 2019. DOI: https://doi.org/10.1007/s00704-019-02940-7. MARIN F.R. ANGELOCCI L.R. NASSIF D.S.P. VIANNA M.S. PILAU F.G. SILVA E.H.F.M. da SOBENKO L.R. GONÇALVES A.O. PEREIRA R.A.A. CARVALHO K.S. Revisiting the crop coefficient - reference evapotranspiration procedure for improving irrigation management Theoretical and Applied Climatology 138 1785 1793 2019 10.1007/s00704-019-02940-7 MARIN, F.R.; ANGELOCCI, L.R.; RIGHI, E.Z.; SENTELHAS, P.C. Evapotranspiration and irrigation requirements of a coffee plantation in Southern Brazil. Experimental Agriculture, v.41, p.187-197, 2005. DOI: https://doi.org/10.1017/S0014479704002480. MARIN F.R. ANGELOCCI L.R. RIGHI E.Z. SENTELHAS P.C. Evapotranspiration and irrigation requirements of a coffee plantation in Southern Brazil Experimental Agriculture 41 187 197 2005 10.1017/S0014479704002480 MBANGIWA, N.C.; SAVAGE, M.J.; MABHAUDHI, T. Modelling and measurement of water productivity and total evaporation in a dryland soybean crop. Agricultural and Forest Meteorology, v.266-267, p.65-72, 2019. DOI: https://doi.org/10.1016/j.agrformet.2018.12.005. MBANGIWA N.C. SAVAGE M.J. MABHAUDHI T. Modelling and measurement of water productivity and total evaporation in a dryland soybean crop Agricultural and Forest Meteorology 266-267 65 72 2019 10.1016/j.agrformet.2018.12.005 MILLER, J.B. A formula for average foliage density. Australian Journal of Botany, v.15, p.141-144, 1967. DOI: https://doi.org/10.1071/BT9670141. MILLER J.B. A formula for average foliage density Australian Journal of Botany 15 141 144 1967 10.1071/BT9670141 MILLER, J.B. The foliage density equation revisited. Journal of the Australian Mathematical Society. Series B. Applied Mathematics, v.27, p.387-401, 1986. DOI: https://doi.org/10.1017/S0334270000005038. MILLER J.B. The foliage density equation revisited Journal of the Australian Mathematical Society. Series B. Applied Mathematics 27 387 401 1986 10.1017/S0334270000005038 NILSON, T. A theoretical analysis of the frequency of gaps in plant stands. Agricultural Meteorology, v.8, p.25-38, 1971. DOI: https://doi.org/10.1016/0002-1571(71)90092-6. NILSON T. A theoretical analysis of the frequency of gaps in plant stands Agricultural Meteorology 8 25 38 1971 10.1016/0002-1571(71)90092-6 OLIVEIRA, E.C.A. de; OLIVEIRA, R.I. de; ANDRADE, B.M.T. de; FREIRE, F.J.; LIRA JÚNIOR, M.A.; MACHADO, P.R. Crescimento e acúmulo de matéria seca em variedades de cana-de-açúcar cultivadas sob irrigação plena. Revista Brasileira de Engenharia Agrícola e Ambiental, v.14, p.951-960, 2010. DOI: https://doi.org/10.1590/S1415-43662010000900007. OLIVEIRA E.C.A. de OLIVEIRA R.I. de ANDRADE B.M.T. de FREIRE F.J. LIRA M.A. JÚNIOR MACHADO P.R. Crescimento e acúmulo de matéria seca em variedades de cana-de-açúcar cultivadas sob irrigação plena Revista Brasileira de Engenharia Agrícola e Ambiental 14 951 960 2010 10.1590/S1415-43662010000900007 OLIVEIRA, R.A. de; DAROS, E.; ZAMBON, J.L.C.; WEBER, H.; IDO, O.T.; ZUFFELLATO-RIBAS, K.C.; KOEHLER, H.S.; SILVA, D.K.T. da. Crescimento e desenvolvimento de três cultivares de cana-de-açúcar, em cana-planta, no Estado do Paraná. Scientia Agraria, v.5, p.87-94, 2004. DOI: https://doi.org/10.5380/rsa.v5i1.1102. OLIVEIRA R.A. de DAROS E. ZAMBON J.L.C. WEBER H. IDO O.T. ZUFFELLATO-RIBAS K.C. KOEHLER H.S. SILVA D.K.T. da. Crescimento e desenvolvimento de três cultivares de cana-de-açúcar, em cana-planta, no Estado do Paraná Scientia Agraria 5 87 94 2004 10.5380/rsa.v5i1.1102 PEARSE, G.D.; WATT, M.S.; MORGENROTH, J. Comparison of optical LAI measurements under diffuse and clear skies after correcting for scattered radiation. Agricultural and Forest Meteorology, v.221, p.61-70, 2016. DOI: https://doi.org/10.1016/J.AGRFORMET.2016.02.001. PEARSE G.D. WATT M.S. MORGENROTH J. Comparison of optical LAI measurements under diffuse and clear skies after correcting for scattered radiation Agricultural and Forest Meteorology 221 61 70 2016 10.1016/J.AGRFORMET.2016.02.001 PETERS, L.P.; CARVALHO, G.; MARTINS, P.F.; DOURADO, M.N.; VILHENA, M.B.; PILEGGI, M.; AZEVEDO, R.A. Differential responses of the antioxidant system of ametryn and clomazone tolerant bacteria. PLoS ONE, v.9, e112271, 2014. DOI: https://doi.org/10.1371/journal.pone.0112271. PETERS L.P. CARVALHO G. MARTINS P.F. DOURADO M.N. VILHENA M.B. PILEGGI M. AZEVEDO R.A. Differential responses of the antioxidant system of ametryn and clomazone tolerant bacteria PLoS ONE 9 e112271 2014 10.1371/journal.pone.0112271 PIEROZAN JUNIOR, C.; KAWAKAMI, J. Efficiency of the leaf disc method for estimating the leaf area index of soybean plants. Acta Scientiarum. Agronomy, v.35, p.487-493, 2013. DOI: https://doi.org/10.4025/actasciagron.v35i4.16290. PIEROZAN C. JUNIOR KAWAKAMI J. Efficiency of the leaf disc method for estimating the leaf area index of soybean plants Acta Scientiarum. Agronomy 35 487 493 2013 10.4025/actasciagron.v35i4.16290 RICHTER, G.L.; ZANON, A.J.; STRECK, N.A.; GUEDES, J.V.C.; KRÄULICH, B.; ROCHA, T.S.M. da; WINCK, J.E.M.; CERA, J.C. Estimativa da área de folhas de cultivares antigas e modernas de soja por método não destrutivo. Bragantia, v.73, p.416-425, 2014. DOI: https://doi.org/10.1590/1678-4499.0179. RICHTER G.L. ZANON A.J. STRECK N.A. GUEDES J.V.C. KRÄULICH B. ROCHA T.S.M. da WINCK J.E.M. CERA J.C. Estimativa da área de folhas de cultivares antigas e modernas de soja por método não destrutivo Bragantia 73 416 425 2014 10.1590/1678-4499.0179 RITTER, A.; MUÑOZ-CARPENA, R. Performance evaluation of hydrological models: Statistical significance for reducing subjectivity in goodness-of-fit assessments. Journal of Hydrology, v.480, p.33-45, 2013. DOI: https://doi.org/10.1016/j.jhydrol.2012.12.004. RITTER A. MUÑOZ-CARPENA R. Performance evaluation of hydrological models: Statistical significance for reducing subjectivity in goodness-of-fit assessments Journal of Hydrology 480 33 45 2013 10.1016/j.jhydrol.2012.12.004 RYU, Y.; NILSON, T.; KOBAYASHI, H.; SONNENTAG, O.; LAW, B.E.; BALDOCCHI, D.D. On the correct estimation of effective leaf area index: does it reveal information on clumping effects? Agricultural and Forest Meteorology, v.150, p.463-472, 2010a. DOI: https://doi.org/10.1016/j.agrformet.2010.01.009. RYU Y. NILSON T. KOBAYASHI H. SONNENTAG O. LAW B.E. BALDOCCHI D.D. On the correct estimation of effective leaf area index: does it reveal information on clumping effects? Agricultural and Forest Meteorology 150 463 472 2010a 10.1016/j.agrformet.2010.01.009 RYU, Y.; SONNENTAG, O.; NILSON, T.; VARGAS, R.; KOBAYASHI, H.; WENK, R.; BALDOCCHI, D.D. How to quantify tree leaf area index in an open savanna ecosystem: a multi-instrument and multi-model approach. Agricultural and Forest Meteorology, v.150, p.63-76, 2010b. DOI: https://doi.org/10.1016/j.agrformet.2009.08.007. RYU Y. SONNENTAG O. NILSON T. VARGAS R. KOBAYASHI H. WENK R. BALDOCCHI D.D. How to quantify tree leaf area index in an open savanna ecosystem: a multi-instrument and multi-model approach Agricultural and Forest Meteorology 150 63 76 2010b 10.1016/j.agrformet.2009.08.007 SBRISSIA, A.F.; SILVA, S.C. da. Comparação de três métodos para estimativa do índice de área foliar em pastos de capim-marandu sob lotação contínua. Revista Brasileira de Zootecnia, v.37, p.212-220, 2008. DOI: https://doi.org/10.1590/S1516-35982008000200006. SBRISSIA A.F. SILVA S.C. da. Comparação de três métodos para estimativa do índice de área foliar em pastos de capim-marandu sob lotação contínua Revista Brasileira de Zootecnia 37 212 220 2008 10.1590/S1516-35982008000200006 SHIOGA, P.S.; GERAGE, A.C.; ARAÚJO, P.M. de; BIANCO, R.; CUSTÓDIO, A.A. de P. Avaliação estadual de cultivares de milho segunda safra 2015. Londrina: IAPAR, 2015. 101p. (IAPAR. Boletim técnico, 86). SHIOGA P.S. GERAGE A.C. ARAÚJO P.M. de BIANCO R. CUSTÓDIO A.A. de P. Avaliação estadual de cultivares de milho segunda safra 2015 Londrina IAPAR 2015 101p IAPAR. Boletim técnico, 86 SOBENKO, L.R.; SOUZA, T.T.; GONÇALVES, A.O.; BIANCHINI, V.J.M.; SILVA, E.H.F.M.; SOUZA, L.T.; MARIN, F.R. Irrigation requirements are lower than those usually prescribed for a maize crop in Southern Brazil. Experimental Agriculture, v.55, p.662-671, 2019. DOI: https://doi.org/10.1017/S0014479718000339. SOBENKO L.R. SOUZA T.T. GONÇALVES A.O. BIANCHINI V.J.M. SILVA E.H.F.M. SOUZA L.T. MARIN F.R. Irrigation requirements are lower than those usually prescribed for a maize crop in Southern Brazil Experimental Agriculture 55 662 671 2019 10.1017/S0014479718000339 VIEIRA JUNIOR, P.A.; DOURADO NETO, D.; BERNARDES, M.S.; FANCELLI, A.L.; MANFRON, P.A.; MARTIN, T.N. Metodologia para estimativa da área foliar de genótipos de milho. Revista Brasileira de Milho e Sorgo, v.5, p.182-191, 2006. DOI: https://doi.org/10.18512/1980-6477/rbms.v5n2p182-191. VIEIRA P.A. JUNIOR DOURADO D. NETO BERNARDES M.S. FANCELLI A.L. MANFRON P.A. MARTIN T.N. Metodologia para estimativa da área foliar de genótipos de milho Revista Brasileira de Milho e Sorgo 5 182 191 2006 10.18512/1980-6477/rbms.v5n2p182-191 WELLES, J.M.; NORMAN, J.M. Instrument for indirect measurement of canopy architecture. Agronomy Journal, v.83, p.818-825, 1991. DOI: https://doi.org/10.2134/agronj1991.00021962008300050009x. WELLES J.M. NORMAN J.M. Instrument for indirect measurement of canopy architecture Agronomy Journal 83 818 825 1991 10.2134/agronj1991.00021962008300050009x WILLMOTT, C.J.; ROBESON, S.M.; MATSUURA, K. A refined index of model performance. International Journal of Climatology, v.32, p.2088-2094, 2012. DOI: https://doi.org/10.1002/joc.2419. WILLMOTT C.J. ROBESON S.M. MATSUURA K. A refined index of model performance International Journal of Climatology 32 2088 2094 2012 10.1002/joc.2419 YAN, G.; HU, R.; LUO, J.; WEISS, M.; JIANG, H.; MU, X.; XIE, D.; ZHANG, W. Review of indirect optical measurements of leaf area index: recent advances, challenges, and perspectives. Agricultural and Forest Meteorology, v.265, p.390-411, 2019. DOI: https://doi.org/10.1016/j.agrformet.2018.11.033. YAN G. HU R. LUO J. WEISS M. JIANG H. MU X. XIE D. ZHANG W. Review of indirect optical measurements of leaf area index: recent advances, challenges, and perspectives Agricultural and Forest Meteorology 265 390 411 2019 10.1016/j.agrformet.2018.11.033