Influence of leaf position that correspond to whole plant severity and diagrammatic scale for white spot of corn

Capucho, Alexandre Sandri; Zambolim, Laércio; Duarte, Henrique da Silva Silveira; Parreira, D. F.; Ferreira, Paulo Afonso; Lanza, F.; Costa, R. V. da; Casela, C. R.

doi:10.1016/j.cropro.2010.04.012

Cited by 28 publications

(20 citation statements)

References 13 publications

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“…Na avaliação de um experimento futuro, a análise estatística provavelmente será mais significativa e os tratamentos serão mais diferenciados com o uso da escala proposta, pois o intervalo em severidade entre as notas é menor em comparação ao uso da primeira escala. Portanto, os resultados aqui obtidos reforçam a importância de validação de uma escala para as futuras avaliações de doenças em plantas, conforme encontrado em vários outros estudos (STONEHOUSE, 1994;LEITE & AMORIN, 2002;GOMES et al, 2004;MICHEREFF et al, 2006;CAPUCHO et al, 2010;CAPUCHO et al, 2011;YADAV et al, 2012, RIOS et al, 2013.…”

Section: Discussionunclassified

“…Os avaliadores tiveram uma tendência em superestimar a severidade da doença, a qual tem sido observada em vários outros estudos envolvendo validação de escalas (NEWTON & HACKETT, 1994;PARKER et al, 1995;DIAZ et al, 2001; LEITE & AMORIM, 2002;CAPUCHO et al, 2010;CAPUCHO et al, 2011;RIOS et al, 2013). Apenas em alguns poucos estudos tem sido verificada a severidade subestimada (MICHEREFF et al, 1998(MICHEREFF et al, , 2000GOMES et al, 2004).…”

Section: Discussionunclassified

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Validação de escala diagramática para quantificação da severidade da antracnose do colmo do milho

et al. 2015

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RESUMO Objetivou-se propor e validar uma escala diagramática para quantificar a antracnose do colmo em milho. A severidade da antracnose foi estimada por dez avaliadores sem o uso de escala em 139 entrenós, e os mesmos avaliadores avaliaram os entrenós usando uma escala publicada anteriormente na literatura (primeira escala) e uma nova escala proposta. Com o uso da escala proposta, todas as variáveis foram significativamentediferentes em relação à primeira escala, e os valores foram mais próximos de uma medição acurada (r=0,97, C b =0.98, u=0.09, υ=1.06, ρ c =0.96 INTRODUÇÃOA antracnose do colmo Colletotrichum graminicola (Ces.) Wils é uma das doenças mais importantes na cultura do milho em vários países, causando acamamento das plantas, redução na produção e qualidade dos grãos (BERGSTROM & NICHOLSON, 1999;COTA et al., 2012;MATIELLO et al., 2013). Os sintomas da antracnose do colmo são mais visíveis após o florescimento das plantas de milho, porém o processo infeccioso inicia-se pelos propágulos provenientes das lesões foliares ou daqueles presentes em restos culturais. Na casca, surgem lesões estreitras, longitudinais e com aspecto encharcado, que são inicialmente de coloração pardo-avermelhada, posteriormente tornando-se marromescuras a negras. Nos tecidos internos do colmo, ocorre uma coloração marrom-escura, que entra em processo de desintegração, afetando o fluxo de água e nutrientes do colmo para a parte superior, podendo ocasionar a morte prematura e o acamamento das plantas (KELLER &

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Section: Discussionunclassified

Validação de escala diagramática para quantificação da severidade da antracnose do colmo do milho

et al. 2015

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“…Generally, SPAD readings from the second and third leaf (2LTF and 3LFT) were the highest, followed by the values from the first and fourth leaf (1LTF and 4LTF), and the value from the fifth leaf was the lowest. The sensitivity of the upper and lower leaves on a plant to environmental stresses has been shown to be different (Watanabe and Kitagawa 2000;Capucho et al 2010). The lower leaf from a rice plant was more sensitive to nitrogen deficiency than the upper one (Zhou and Wang 2003).…”

Section: Discussionmentioning

confidence: 98%

Detection of brown planthopper infestation based on SPAD and spectral data from rice under different rates of nitrogen fertilizer

et al. 2014

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Reflectance and SPAD readings were measured in rice grown under different nitrogen fertilizer rates and infested with different numbers of brown planthopper (BPH), Nilaparvata lugens, to assess the relationships among these variables. The results showed that SPAD readings and reflectance from rice were significantly affected by BPH infestations and nitrogen fertilizer rates, whereas there was no interaction between the two factors. SPAD readings and reflectance decreased as BPH infestations increased but they increased as nitrogen fertilizer rates were increased. SPAD readings varied with position of leaf on the same stem of rice. The fourth and fifth leaves were more sensitive to BPH infestations than the first and second regardless of application rates of urea. The ratio indices of SPAD readings of the fourth to first leaf (RSPAD 4/1 ), and fourth to second leaf (RSPAD 4/2 ) were significantly related to BPH infestations, and they were relatively independent of nitrogen fertilizer rates in the single stem rice. The spectral reflectance from rice canopy significantly decreased in the near-infrared wavelength range as BPH infestations increased. The modified chlorophyll absorption ratio index (MCARI 710 ) was found more suitable to relate the numbers of BPH under different nitrogen fertilizer rates and durations of BPH infestation. The main effects of BPH infestations on SPAD reading and reflectance indices were consistent regardless of nitrogen application rates. Therefore, SPAD reading and spectral indices have potential to detect BPH infestations in rice fields.

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“…In most studies involving the validation of SAD sets to determine disease severity on leaves, raters have shown a tendency to overestimate the severity (Newton & Hackett, ; Parker et al ., ; Diaz et al ., ; Capucho et al ., ; Lenz et al ., ; Rios et al ., ), although in a few studies, the severity was underestimated (Michereff et al ., ; Gomes et al ., ; Duarte et al ., ). In the present study, an overestimate of spot blotch severity on wheat using the SAD set was also observed.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, the risk of erroneous decisions or type II errors in subsequent statistical analysis will be minimized (Nutter et al ., ; Bock et al ., ). SAD sets have been demonstrated to improve the accuracy and reliability of estimates of several diseases affecting crops of economic importance, such as Asian soybean rust on soybeans (Godoy et al ., ), coffee leaf rust on coffee (Capucho et al ., ), white spot on corn (Capucho et al ., ), ramularia on cotton (Aquino et al ., ), early blight on potato (Duarte et al ., ), blast on wheat (Rios et al ., ) and brown spot on rice (Lenz et al ., ). The SAD set developed and validated in the present study should be a useful tool for estimating spot blotch severity on wheat, with accuracy, precision and reliability.…”

Section: Discussionmentioning

confidence: 99%

Development and validation of a set of standard area diagrams to aid in estimation of spot blotch severity on wheat leaves

et al. 2013

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This study aimed to develop and validate a standard area diagram (SAD) set to quantify the severity of spot blotch, caused by Bipolaris sorokiniana, on wheat leaves. The proposed SAD set includes images of leaves with 11 distinct disease severities (0Á1, 1, 5, 10, 20, 30, 40, 50, 60, 70 and 83%). The SAD set was validated by 12 raters without experience in evaluating plant disease. Lin's concordance correlation analysis of estimated versus actual disease severity (based on image analysis) showed that precision and accuracy improved for all raters using the SAD set in contrast to assessments made without it. The SAD set improved accuracy (coefficient of bias, C b = 0Á88 and 0Á99, without and with the SAD set, respectively) and agreement (Lin's concordance correlation coefficient, q c = 0Á81 and 0Á96 without and with the SAD set, respectively) of the estimates of severity. The severity estimates were also more reliable when using the SAD set (coefficient of determination, R 2 = 0Á76 unaided and R 2 = 0Á92 with the SAD set, and intra-class correlation q = 0Á79 without the SAD set and q = 0Á95 using the SAD set). The SAD set proposed in this study will improve the accuracy and reliability of estimates of spot blotch severity on wheat leaves.

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Influence of leaf position that correspond to whole plant severity and diagrammatic scale for white spot of corn

Cited by 28 publications

References 13 publications

Validação de escala diagramática para quantificação da severidade da antracnose do colmo do milho

Validação de escala diagramática para quantificação da severidade da antracnose do colmo do milho

Detection of brown planthopper infestation based on SPAD and spectral data from rice under different rates of nitrogen fertilizer

Development and validation of a set of standard area diagrams to aid in estimation of spot blotch severity on wheat leaves

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