A simple model relating yield loss to weed density

Cousens, Roger

doi:10.1111/j.1744-7348.1985.tb01567.x

Cited by 605 publications

(650 citation statements)

References 15 publications

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“…A rectangular non-linear hyperbolic regression model (Cousens, 1985) was fitted to the wheat yield data and Emex species density to analyze the relationship between wheat yield loss (YL) and Emex species density (d). The model equation was:…”

Section: Discussionmentioning

confidence: 99%

Wheat Yield Loss in a Two Species Competition with Emex australis and Emex spinosa

et al. 2016

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-Emex australis and E. spinosa are significant weed species in wheat and other crops. Information on the extent of competition of the Emex species will be helpful to access yield losses in wheat. Field experiments were conducted to quantify the interference of tested weed densities each as single or mixture of both at 1:1 on their growth and yield, wheat yield components and wheat grain yield losses in two consecutive years. Dry weight of both weed species increased from 3-6 g m -2 with every additional plant of weed, whereas seed number and weight per plant decreased with increasing density of either weed. Both weed species caused considerable decrease in yield components like spike bearing tillers, number of grains per spike, 1000-grain weight of wheat with increasing density population of the weeds. Based on non-linear hyperbolic regression model equation, maximum yield loss at asymptotic weed density was estimated to be 44 and 62% with E. australis, 56 and 70% with E. spinosa and 63 and 72% with mixture of both species at 1:1 during both year of study, respectively. It was concluded that E. spinosa has more competition effects on wheat crop as compared to E. australis. Keywords

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Section: Discussionmentioning

confidence: 99%

Wheat Yield Loss in a Two Species Competition with Emex australis and Emex spinosa

et al. 2016

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“…A non-linear rectangular hyperbolic regression model (Cousens, 1985) where Y is the observed wheat yield (kg ha -1 ) in a particular weed density, Y wf is the weed free crop yield, i is the percent of yield loss per unit of weed density (d) as d→0, d is weed density, A is the asymptotic value of the maximum yield loss (%), as d→∞. Parameter estimates were determined for the model using the nonlinear regression technique.…”

Section: Discussionmentioning

confidence: 99%

“…A model of density-yield (Cousens, 1985) was used to characterize chickpea yield across A. tenuifolius density. The models estimated that the yields of weed free chickpea (Y wf ) were 2458 kg ha -1 (95% CI [2376,2541]) and 2563 kg ha -1 (95% CI [2484,2641] (Table 3).…”

Section: Estimation Of Chickpea Yield and Yield Lossesmentioning

confidence: 99%

Wild onion (Asphodelus tenuifolius) competition in rainfed chickpea-chickpea cropping system

et al. 2015

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-Chickpea yield potential is limited by weed competition in typical chickpea growing areas of Pakistan where zero tillage crop grown on moisture conserved from rains received during the months of September and August. The objective of this work was to evaluate the growth and yield characteristics of chickpea grown in coexistence with increasing densities of wild onion (Asphodelus tenuifolius). The experiment was comprised of six density levels viz. zero, 20, 40, 80, 160 and 320 plants m -2 of A. tenuifolius. A decrease in chickpea primary and secondary branches per plant, pods per plant, seeds per pod, 100-seed weight and seed yield was observed due to more accumulation of dry matter per increasing densities of A. tenuifolius. The increase in A. tenuifolius density accelerated chickpea yield losses and reached the maximum values of 28, 35, 42, 50, 58 and 96% at 20, 40, 80, 160 and 320 A. tenuifolius plants m -2 , respectively. The yield loss estimation model showed that chickpea losses with infinite A. tenuifolius density were 60%. Yield reduction could be predicted by 2.52% with increase of one A. tenuifolius plant m -2 . It is concluded that A. tenuifolius has a strong influence on chickpea seed yield and showed a linear response at the range of densities studied. Keywords:Cicer arietinum, weed density, yield components, grain yield. de densidade viz. de zero, 20, 40, 80, 160 28, 35, 42, 50, 58 e 96% em 20, 40, 80, 160 e 320 A. tenuifolius RESUMO -Grão de bico potencial de produção é limitada pela competição com plantas daninhas em áreas de cultivo de sementes do grão típico do Paquistão, onde o plantio direto de culturas cultivadas em umidade conservada de chuvas de monção de verão. O objetivo deste trabalho foi avaliar o crescimento ea produção de grão de bico personagens cultivadas em convivência com o aumento da densidade de cebola Silvestre (Asphodelus tenuifolius). O experimento foi composto de seis níveis

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“…When analyzed under very low weed density, the tomato yield loss is positive and linearly related to infestation (Portugal & Moreira, 2009). However, when studied through a wide range of weed densities, the crop yield loss follows a rectangular hyperbole model (Cousens, 1985;Portugal & Vidal, 2009). When weed density and time of interference are analyzed together, it is possible to establish tolerance levels for the weed infestation before any economic impact on the crop yield and quality can be detected (Portugal & Vidal, 2009;Portugal & Moreira, 2011).…”

Section: Introductionmentioning

confidence: 99%

QUALITY OF PROCESSING TOMATO FRUITS IN COMPETITION WITH Solanum americanum

Portugal

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Moreira³

et al. 2015

Planta daninha

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-Five experiments were conducted to evaluate the hypothesis that Solanum americanum density and time of coexistence affect the quality of processing tomato fruit. The tomato crop was established using either the direct drilling or the transplanting technique. The factors evaluated consisted of weed density (from 0 up to 6 plants m -2 ) and time of weed interference (early bloom stage, full flowering stage, fruit filling, and harvest time). The effects of competition on tomato fruit quality were analysed using a multiple model. Tomato variables evaluated included industrial fruit types (which depended on ripeness and disease infection) and soluble solids level ( o brix). Tomato fruit quality is dependent on the factors tested. Under low densities (< 6 plants m -2 ) of S. americanum there was a small impact on the quality of the tomato fruits. The percentage of grade A (mature fruit with red color and without pathogen infection) tomato fruits is the variable most affect by the independent variables. The impact of these independent variables on the percentage of grade C (green and/or with more than 15% disease infection) tomato yield was of smaller magnitude and in an inverse trend as the observed for grade A. The level of soluble solids was influenced by the weed interference on only two experiments, but the impact was of small magnitude. The impact of the results on current and future crop management practices is discussed.Keywords: weed competition, critical period, density-dependent processes, threshold. Palavras-chave: interferência, período crítico, processos dependentes da densidade, nível de dano econômico. RESUMO -Cinco experimentos foram conduzidos para avaliar a hipótese de que a densidade de Solanum americanum e o tempo de convivência podem alterar a qualidade dos frutos do tomate para a indústria. O tomate foi cultivado usando-se o plantio direto ou a técnica de transplante. Os fatores avaliados consistiram da densidade de plantas daninhas (de 0 até 6 plantas m -2 ) e do tempo de interferência delas (fases de pré-florada, pleno florescimento, enchimento de frutos e colheita). Os efeitos da interferência sobre a qualidade dos frutos do tomateiro foram analisados utilizando um modelo múltiplo. As variáveis de tomate avaliadas foram tipos de fruta para indústria (em função da maturação e infecção da doença) e teor de sólidos solúveis ( o brix). A qualidade dos frutos de tomate é dependente dos fatores testados. Sob baixa densidade (<6 plantas m -

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A simple model relating yield loss to weed density

Cited by 605 publications

References 15 publications

Wheat Yield Loss in a Two Species Competition with Emex australis and Emex spinosa

Wheat Yield Loss in a Two Species Competition with Emex australis and Emex spinosa

Wild onion (Asphodelus tenuifolius) competition in rainfed chickpea-chickpea cropping system

QUALITY OF PROCESSING TOMATO FRUITS IN COMPETITION WITH Solanum americanum

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