Estimativa da área foliar de cinco espécies do gênero Amaranthus usando dimensões lineares do limbo foliar

Carvalho, Saul Jorge Pinto de; Christoffoleti, Pedro Jacob

doi:10.1590/s0100-83582007000200011

Cited by 13 publications

(12 citation statements)

References 15 publications

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“…All equations had coefficients of determination above 90%; however, among the 12 sowing dates, only eight were similar to the general model (Table 3). In this case, the models were compared by analyzing the overlap of the confidence interval (Carvalho & Christoffoleti, 2007).…”

Section: Resultsmentioning

confidence: 99%

Initial growth and development of southern sandbur based on thermal units

et al. 2014

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-Availability of basic information on weed biology is an essential tool for designing integrated management programs for agricultural systems. Thus, this study was carried out in order to calculate the base temperature (Tb) of southern sandbur (Cenchrus echinatus), as well as fit the initial growth and development of the species to accumulated thermal units (growing degree days -GDD). For that purpose, experimental populations were sown six times in summer/autumn conditions (decreasing photoperiod) and six times in winter/spring condition (increasing photoperiod). Southern sandbur phenological evaluations were carried out, on alternate days, and total dry matter was measured when plants reached the flowering stage. All the growth and development fits were performed based on thermal units by assessing five base temperatures, as well as the absence of it. Southern sandbur development was best fit with Tb = 12 o C, with equation y = 0,0993x, where y is the scale of phenological stage and x is the GDD. On average, flowering was reached at 518 GDD. Southern sandbur phenology may be predicted by using mathematical models based on accumulated thermal units, adopting Tb = 12 o C. However, other environmental variables may also interfere with species development, particularly photoperiod. Keywords:Cenchrus echinatus, weed, biology, growing degree days, modeling. RESUMO -A disponibilidade de informações básicas sobre a biologia de plantas daninhas é uma ferramenta essencial para a elaboração de programas de manejo integrado em sistemas agrícolas. Nesse sentido, este trabalho foi desenvolvido com o objetivo de calcular a temperatura basal (Tb) do capim-carrapicho (Cenchrus echinatus), bem como ajustar o crescimento e o desenvolvimento inicial da espécie às unidades térmicas acumuladas (graus-dia). Para isso, foram realizadas seis semeaduras de populações experimentais em condição de verão/outono (fotoperíodo decrescente) e seis semeaduras em inverno/primavera (fotoperíodo crescente

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Section: Resultsmentioning

confidence: 99%

Initial growth and development of southern sandbur based on thermal units

et al. 2014

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“…The equations are considered equivalents when the confidence intervals are overlapped (CARVALHO; CHRISTOFFOLETI, 2007), so that the regression analyses must be processed separately if the overlapping do not occurred.…”

Section: Thismentioning

confidence: 99%

“…This non-destructive, easy and quick method for leaf area estimation is important for plant growth evaluation in field conditions (BIANCO et al, 2007). The relationship between the real leaf area and the linear measures of leaves had been studied successfully for weed leaf area determination based on regression analysis by Carvalho and Christoffoleti (2007), Bianco et al (2007), Bianco et al (2008a and b) and others.…”

Section: Introductionmentioning

confidence: 99%

Determination of Merremia cissoids leaf area using the linear measures of the leaflets

et al. 2011

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ABSTRACT. Knowledge of the weed leaf area may give support to study the interference relationships between weeds and crops. The objective of this research was to determine a mathematical equation for M. cissoides leaf area estimation based on the relationship between the leaf blade linear measures. Leaves of the species were collected from a variety of agroecosystems at São Paulo State University, Jaboticabal, São Paulo State, Brazil, measuring the length (L), maximum width (W) and real leaf blade area of the three kinds of leaflets. Linear equations Y = a x (X) were estimated for each kind of leaflet. The confidence intervals of the primary leaflet equation overlapped those ones from the secondary leaflet equation, and then only one equation was considered for these leaflets. So, an equation of principal leaflet plus that one of primary + secondary leaflets were used to determine the M. cissoides leaf area. Thus, the leaf area of the species might be determined by the sum of the leaf areas of the principal leaflet with the primary + secondary leaflets, according to the equation LA est = 0.501 x (X) + 2.181 x (Z), where X indicates L x W of the principal leaflet and Z indicates medium L x W of the primary + secondary leaflets, respectively.Keywords: weed, growth, roadside woodrose, linear fit. RESUMO. Determinação da área foliar de Merremia cissoides utilizando dimensões lineares dos folíolos.O conhecimento da área foliar de plantas daninhas pode auxiliar o estudo das relações de interferência entre elas e as culturas agrícolas. O objetivo desta pesquisa foi determinar uma equação matemática que estime a área foliar de Merremia cissoides, a partir da relação entre as dimensões lineares dos limbos foliares. Folhas da espécie foram coletadas de diferentes locais na Universidade Estadual Paulista, Jaboticabal, Estado de São Paulo, Brasil, medindo-se o comprimento (C), a largura máxima (L) e a área foliar de três tipos de folíolos. Foram estimadas equações lineares Y = a x (X) para cada tipo de folíolo. Houve sobreposição dos intervalos de confiança das equações dos folíolos primário e secundário, por isso considerou-se uma única equação da média desses folíolos, além da equação do folíolo principal, para caracterização da área foliar de M. cissoides. Assim, a área foliar dessa espécie pode ser estimada pelo somatório das áreas dos limbos foliares dos folíolos principal e primário + secundário, por meio da equação AF est = 0,501 x (X) + 2,181 x (Z), em que X indica C x L do folíolo principal e Z indica C x L médios dos folíolos primário + secundário, respectivamente.Palavras-chave: planta daninha, crescimento, jitirana, ajuste linear.

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“…A generalized leaf area equation LA = α × L × W for maize plants was proposed by Montgomery, (1911), based on a rectangle area L × W (L -leaf length, W -leaf width) and on a weighing factor (α) equal to 0.75. However, several authors indicated that the weighting factor may vary depending on the maize variety (Bange et al, 2000;Carvalho and Christoffoleti, 2007;Tivet et al, 2001), plant development stage (Bange et al, 2000), environmental conditions and agronomic practices (Elings, 2000;Sezer et al, 2009). Therefore, application of this classic equation requires a measurement of length and width of all leaves on a plant, which is very labour and time consuming, and can be a source of errors.…”

Section: Introductionmentioning

confidence: 99%

Maize leaf area estimation in different growth stages based on allometric descriptors

Mananze¹,

Pôças²,

Cunha³

2018

Afr. J. Agric. Res.

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The literature points out the need for leaf area (LA) calibration models that are suitable for specific varieties (variety-specific). These models should be capable of coping with different crop conditions, growth stages, and agronomic practices. The objective of the current study was to develop a model for estimating the LA of maize (Zea mays L.), considering the entire growth cycle, based on non-destructive allometric measurements. The proposed model was derived from a multiple regression analysis of LA data obtained from digital image processing, including the number of leaves per plant (NL) and the product of major leaf length per major leaf width of the greater leaf (MLL × MLW). A high percent of data variability in the LA of maize plants was explained by the model, both in the calibration and validation phases (R 2 = 0.90; n = 30). Overall, the selected model presented good performance in the estimation of LA of maize, variety PAN 53, cultivated under the conditions of the present study area. Additionally, the model enabled the estimation of LA at different stages of the crop cycle. The results indicated a positive potential for using the developed model to support several maize cultural practices.

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Estimativa da área foliar de cinco espécies do gênero Amaranthus usando dimensões lineares do limbo foliar

Cited by 13 publications

References 15 publications

Initial growth and development of southern sandbur based on thermal units

Initial growth and development of southern sandbur based on thermal units

Determination of Merremia cissoids leaf area using the linear measures of the leaflets

Maize leaf area estimation in different growth stages based on allometric descriptors

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