Explanatory Models in Crop Physiology

Loomis, R. S.; Rabbinge, R.; Ng, Ehy

doi:10.1146/annurev.pp.30.060179.002011

Cited by 158 publications

(81 citation statements)

References 64 publications

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“…We are developing dynamic multilevel explanatory models (sensu Loomis et al 1979;Penning de Vries 1983) of forest ecosystem mass and energy exchange. One component of our program is the construction and testing of a big-leaf representation of a canopy that simulates leaf physiology and mass, energy, and momentum exchanges.…”

Section: Introductionmentioning

confidence: 99%

Testing a Mechanistic Model of Forest-Canopy Mass and Energy Exchange Using Eddy Correlation: Carbon Dioxide and Ozone Uptake by a Mixed Oak-Maple Stand

Amthor¹,

Goulden²,

Munger³

et al. 1994

Functional Plant Biol.

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A big-leaf model of C3-canopy mass and energy exchange was used to predict hourly C02 and O3 uptake by a mixed deciduous Quercus-Acer (oak-maple) stand in central Massachusetts, USA. The model is based on canopy-radiation interactions, leaf mesophyll metabolism (photosynthetic electron transport, carboxylation and oxygenation of ribulose 1,s-bisphosphate [RuP2] by RuPz carboxylase/oxygenase [Rubisco], and respiration), physical transport conductances of mass and heat above and within the canopy, conductances of mass at the leaf surface and in the mesophyll, and mass and energy exchange at the soil surface (forest floor). Predictions of hourly C02 and O3 uptake were compared to independent whole-forest C02 and O3 exchange measurements made by the eddy correlation method during a 68 day period in the summer and early autumn of 1992. Predicted hourly C02 exchange rate was strongly correlated (r --+0.91) with measured hourly COz exchange, but mean day-time predicted whole-forest C02 uptake was c. 13% (c. 1.13 pmol C 0 2 m-2 s-') greater than C 0 2 uptake measured by eddy correlation. The model tended to overpredict C02 uptake during late afternoon, but was accurate during the rest of the day. Predicted and measured O3 uptake rates also were positively correlated (r * +0.76). The diurnal patterns of predicted and measured O3 uptake indicated that stomata1 conductance (g,) was accurately predicted during the morning, but in the afternoon the model overpredicted g,. This pattern was consistent with the overprediction of afternoon C 0 2 uptake, and suggested that a feedback inhibition of photosynthesis occurred in the afternoon. This might have been related to source-sink imbalance following several hours of photosynthesis. On the whole, and in spite of the simplifications inherent in the big-leaf representation of the canopy, the model is useful for predicting forest-environment interactions and for interpreting mass and energy exchange measurements.

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Section: Introductionmentioning

confidence: 99%

Testing a Mechanistic Model of Forest-Canopy Mass and Energy Exchange Using Eddy Correlation: Carbon Dioxide and Ozone Uptake by a Mixed Oak-Maple Stand

Amthor¹,

Goulden²,

Munger³

et al. 1994

Functional Plant Biol.

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“…El-Sharkawy of crop irradiance interception in relation to canopy photosynthesis laid a foundation for crop modeling (de Wit, 1965;Duncan et al, 1967;Duncan, 1973;Loomis et al, 1979;Whisler et al, 1986;Penning de Vries et al, 1989;Boote and Loomis, 1991;Cowling and Field, 2003) and significantly increased our insights on how cropping systems work in response to changes in environmental factors. Moreover, desired morphological, structural and functional plant traits can be identified using this type of analysis.…”

Section: Role Of Growth Analysis Leaf Area Index Crop Light Intercementioning

confidence: 99%

“…Also, photosynthesis research laid the foundation of and is still contributing to crop modeling (de Wit, 1965;Duncan et al, 1967;Duncan, 1973;Baker, 1979;Loomis et al, 1979;Bunce, 1986;Penning de Vries et al, 1989;Baker and Landivar, 1991;Boote and Loomis, 1991). Such models, when built and calibrated on sound data from crops grown under field conditions, are useful tools for integrating research results at various organism levels, as well as for predicting crop responses to environmental conditions in different ecosystems (ElSharkawy, 2005).…”

Section: Photosynthesis and Its Relation To Crop Productivity: Some Ementioning

confidence: 99%

“…Such an understanding of the processes involved there leads to explanatory models (Loomis et al, 1979) for process behavior, which possibly can be used to determine which process traits could be most efficiently improved in a breeding program. Such models need then to be improved with further research.…”

Section: Photosynthesis and Its Relation To Crop Productivity: Some Ementioning

confidence: 99%

“…Involving farmers in the research process, via the new approach of farmer participatory research , is necessary for increasing research effectiveness and applicability of new technologies (Hellin et al, 2006;Leisa, 2006). These research efforts would be further enhanced by linking and integrating the various branches of science from the molecular level (i.e., reductionistic approaches) to the whole-plant and ecosystem levels (i.e., holistic approaches) in interdisciplinary/interinstitutional teams (Loomis et al 1979;Loomis and Connor, 1992;Loojin, 1999;Delmer, 2005). Moreover, the use of available research tools in molecular biology and genetic engineering, as well as crop modeling, is essential for increasing efficiency of research (Kramer, 1980;Thornley and Johnson, 1990;Boote and Loomis, 1991;Shorter et al, 1991;Cohen, 1993;Evans, 1993b;Leisinger, 1995;Jackson et al, 1996;ElSharkawy, 2005).…”

Section: Introductionmentioning

confidence: 99%

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Utility of basic research in plant/crop physiology in relation to crop improvement: a review and a personal account

El‐Sharkawy

2006

Braz. J. Plant Physiol.

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Utilidade da pesquisa básica em fisiologia vegetal e em fisiologia da produção em relação ao melhoramento das culturas: uma revisão e uma análise pessoal: A pesquisa e o desenvolvimento agrícola têm função essencial no desenvolvimento econômico das nações, provendo segurança alimentar para uma população em constante crescimento demográfico. Em países desenvolvidos, as lacunas entre a produção potencial e a produção real são sobremodo estreitas, devido a uma combinação de tecnologias avançadas, novas variedades altamente produtivas e aplicação de agroquímicos em sistemas de produção altamente mecanizados. Na maioria daqueles países, a produção agrícola supera a demanda nacional, resultando em excedentes para a exportação. Em muitos países em desenvolvimento, entretanto, a produtividade agrícola está ainda muito abaixo de seu potencial devido a limitações técnicas e sócio-econômicas. Déficit alimentar é a norma em países pobres e subdesenvolvidos, os quais requerem vultosas importações de alimentos. Para aliviar parcialmente essa situação, pesquisas de cunho agrícola devem ser reforçadas. Como ramos das ciências básicas, a fisiologia vegetal e a fisiologia da produção têm sido freqüentemente criticadas por não traduzirem seus resultados de pesquisa em melhoria da produtividade. Este artigo é focado nesse tema, apresentando uma avaliação das realizações pretéritas da pesquisa fisiológica e de seus impactos sobre o melhoramento das culturas e sobre a produção de alimentos. Discutem-se deficiências e limitações de pesquisas isoladas e de pouca relevância, juntamente com opiniões do cientista sobre como pesquisas efetivas na área da fisiologia devem ser conduzidas e integradas dentro de equipes de pesquisa multidisciplinares associadas ao melhoramento vegetal. Exemplos de pesquisas de sucesso na fisiologia da produção e suas contribuições para aumentar a produtividade agrícola são apresentados. Todos esses aspectos apontam para a necessidade de pronto financiamento da pesquisa básica por setores públicos e privados de países desenvolvidos. Palavras-chave: agricultura, ecofisiologia, ecossistemas, estresse hídrico, fotoperíodo, fotossíntese C 4 , hormônios, melhoramento, produtividade, solo, tolerância à seca Agricultural research and development plays an essential role in a nation s economic development, providing for food security for an ever-increasing population. In developed countries, the gap between potential and actual yield is largely closed because of a combination of advanced technologies, high-yielding new varieties and the application of agrochemicals in highly mechanized production systems. In most of these countries, agricultural production exceeds national demand, resulting in excess products for export. In many of the developing countries, however, agricultural productivity is still far below what it should be because of multiple technical and socio-economic constraints. Food deficits are the norm in poor and middle-income countries, requiring expensive food imports. To partially alleviate this situati...

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