Limitations to carbon assimilation by mild drought in nectarine trees growing under field conditions

Osório, María Leonor; BREIA, E; Rodrigues, A. L.; Osório, Júlio; ROUX, X; Daudet, F.A.; Ferreira, Maria Isabel; Chaves, M. M.

doi:10.1016/j.envexpbot.2004.11.003

Cited by 27 publications

(25 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Based on the above statements and on the CCA, we conclude that diffusive (stomatal) rather than photochemical or biochemical constraints are largely responsible for the diurnal fluctuations of A. A similar suggestion was reported for nectarine trees by Osório et al (2006), who found that diurnal changes in A were dominated by changes in g s with unchanging non-structural carbohydrate pools during the day, which argues against feedback inhibition by the accumulation of carbohydrate.…”

Section: Diurnal Variations In Photosynthesissupporting

confidence: 61%

Photosynthetic limitations in coffee plants are chiefly governed by diffusive factors

Batista

Araújo

Antunes

et al. 2011

Trees

View full text Add to dashboard Cite

It has long been held that the regulation of photosynthesis in source leaves may be controlled by carbohydrates. The mechanisms that govern the diurnal fluctuation of photosynthesis and the potential role of feedback regulation by carbohydrates during photosynthesis in coffee (Coffea arabica) leaves were investigated in three independent and complementary experiments. An integrative approach using gas exchange measurements in addition to carbon isotope labelling and steady-state carbohydrate and amino acid analysis was performed. Canonical correlation analysis was also performed. In fieldgrown plants under naturally fluctuating environmental conditions (Experiment I), the overall pattern of gas exchange was characterised by both low stomatal conductance (g s ) and net carbon assimilation rate (A) in the afternoon; no apparent signs of photoinhibition were observed. Under conditions of low air evaporative demand (Experiment II), only slight decreases (*20%) in A were observed at the end of the day, which were associated with a reduction (*35%) in g s . For both conditions, any increase in carbohydrate and amino acid pools over the course of the day was small. In leaves from girdled branches (Experiment III), a remarkable decrease in A and particularly in g s was observed, as were increases in starch but not in hexoses and sucrose pools. Furthermore, the rate of 14 CO 2 uptake (assessed under saturating CO 2 conditions) and the partitioning of recently fixed 14 C were not affected by girdling. It is proposed that the diurnal oscillations in A and the differences in A in leaves from girdled and non-girdled branches were merely a consequence of diffusive limitations rather than from photochemical constraints or direct metabolite-mediated down-regulation of photosynthesis.

show abstract

Section: Diurnal Variations In Photosynthesissupporting

confidence: 61%

Photosynthetic limitations in coffee plants are chiefly governed by diffusive factors

Batista

Araújo

Antunes

et al. 2011

Trees

View full text Add to dashboard Cite

show abstract

“…The maintenance of the high values of photosynthesis along the day was also observed in water-stressed plants of Carica papaya (L.) by Marler & Mickelbart (1998), and seems to be associated with the vigorous growth habitat of this species. However previous works had shown that daily gas exchange pattern of water stressed plants usually depends on the time of day (Romero & Botía 2006;Osório et al 2006). This pattern was not observed in this study, since the rates of A and E showed little variation along the day on the water stressed plants.…”

Section: Resultscontrasting

confidence: 46%

Growth and carbon assimilation limitations in Ricinus communis (Euphorbiaceae) under soil water stress conditions

Sausen

Rosa

2010

Acta Bot. Bras.

View full text Add to dashboard Cite

RESUMO -(Crescimento e limitações à assimilação de carbono em Ricinus communis (Euphorbiaceae) sob condições de estresse hídrico do solo). A disponibilidade hídrica pode infl uenciar o ganho de carbono e o crescimento, com grande impacto na produtividade das plantas. Ricinus communis (L.), uma espécie resistente à seca, é uma cultura de grande importância econômica no Brasil, devido ao seu uso na indústria química e para a produção de biocombustíveis. Alguns dos mecanismos envolvidos na resistência à seca desta espécie foram analisados através de um progressivo estresse hídrico em plantas cultivadas em vasos sob condições de casa de vegetação. A suspensão da irrigação por 53 dias decresceu o conteúdo gravimétrico de água no solo e o potencial hídrico das folhas. O crescimento das plantas foi negativamente e signifi cativamente reduzido pelo aumento do défi cit hídrico do solo. Com a suspensão da irrigação, a assimilação de carbono e a transpiração foram reduzidas e permaneceram praticamente constantes ao longo do dia. A análise das curvas A/C i demonstrou o aumento da limitação estomática, indicando que a limitação imposta pelo fechamento dos estômatos é o principal responsável pela redução da fotossíntese. A efi ciência de carboxilação e a taxa de transporte de elétrons não foram afetadas pelo estresse hídrico até 15 dias de suspensão da irrigação. A resistência à seca da mamona parece estar relacionada a uma resposta inicial e pronunciada do crescimento, a um efi ciente controle estomático e a capacidade de manter uma alta taxa de fi xação de CO 2 sob condições de estresse hídrico. Palavras-chave: curvas A/Ci, estresse hídrico, fotossíntese, limitação estomática, padrão diário ABSTRACT -(Growth and limitations to carbon assimilation in Ricinus communis (Euphorbiaceae) under soil water stress conditions). Water availability may infl uence plant carbon gain and growth, with large impacts on plant yield. Ricinus communis (L.), a drought resistant species, is a crop with increasing economic importance in Brazil, due to its use in chemical industry and for the production of biofuels. Some of the mechanisms involved in this drought resistance were analyzed in this study by imposing progressive water stress to pot-grown plants under glasshouse conditions. Water withholding for 53 days decreased soil water gravimetric content and the leaf water potential. Plant growth was negatively and signifi cantly reduced by increasing soil water defi cits. With irrigation suspension, carbon assimilation and transpiration were reduced and remained mostly constant throughout the day. Analysis of A/ C i curves showed increased stomatal limitation, indicating that limitation imposed by stomatal closure is the main factor responsible for photosynthesis reduction. Carboxylation effi ciency and electron transport rate were not affected by water stress up to 15 days after withholding water. Drought resistance of castor bean seems to be related to a pronounced, early growth response, an effi cient stomatal control and the capacity to keep...

show abstract

“…[3.9] in Supplemental Table S3). The photosynthesis response to a vapor pressure deficit has been described by an exponential decay function (e.g., Osório et al, 2006) but usually more sophisticated approaches have been used (Collatz et al, 1992;Yin and Struik, 2009). The photosynthesis response to temperature is discussed below.…”

Section: Group Iii-photosynthesismentioning

confidence: 99%

Nonlinear Regression Models and Applications in Agricultural Research

2015

View full text Add to dashboard Cite

In data analysis, we often ask the following questions:Which is the best model to describe our data? Which is the best statistical index to judge the goodness of fit? How do we choose among competing models? There are no simple answers to these questions. Here we attempt to provide agronomists with a general framework on how to approach these questions appropriately. Our specific objectives are: (i) to provide a succinct overview of nonlinear models and to develop a guideline to understand the family of functions used in agricultural applications; (ii) to indicate techniques to modify nonlinear models and how to cope with multiple nonlinear models; (iii) to discuss key methodological issues on parameter estimation, model performance, and comparison; and (iv) to demonstrate step-by-step analysis of experimental data using a nonlinear regression model. The structure follows the flow diagram in Fig. 1. We start with the definition of nonlinear regression models and discuss their main advantages and disadvantages. Then we present 77 nonlinear functions (including those in supplemental tables) with references to applications in agriculture. We offer an updated overview of methodologies to fit models, choose starting values, assess goodness of fit, select the best models, and evaluate residuals. Finally, we reanalyze experimental data on biomass growth with time (Danalatos et al., 2009). NONLINEAR REGRESSION MODELS DefinitionIn general, statistical models used in agricultural applications can be described with the following notation:where y is the response variable, f is the function or model, x are the inputs, q denotes the parameters to be estimated, and e is the error. Each parameter can be evaluated for whether it is linear or not: if the second derivative of the function with respect to a parameter is not equal to zero, then the parameter is nonlinear. Thus a given function ( f ) can have a mix of linear and nonlinear parameters. Why Should We Use Nonlinear Models?The main advantages of nonlinear models are parsimony, interpretability, and prediction (Bates and Watts, 2007). In general, nonlinear models are capable of accommodating a vast variety of mean functions, although each individual nonlinear model can be less flexible than linear models (i.e., polynomials) in terms of the variety of data they can describe; however, nonlinear models appropriate for a given application can be more parsimonious (i.e., there will be fewer parameters involved) and more easily interpretable. Interpretability comes from the fact that the parameters can be associated with a biologically meaningful process. For example, one of the most widely used nonlinear models is the logistic equation (Eq. [2.1] in Table 1). This model describes the pervasive S-shaped growth curve. The ABSTRACT Nonlinear regression models are important tools because many crop and soil processes are better represented by nonlinear than linear models. Fitting nonlinear models is not a single-step procedure but an involved process that requires careful examinati...

show abstract

Limitations to carbon assimilation by mild drought in nectarine trees growing under field conditions

Cited by 27 publications

References 0 publications

Photosynthetic limitations in coffee plants are chiefly governed by diffusive factors

Photosynthetic limitations in coffee plants are chiefly governed by diffusive factors

Growth and carbon assimilation limitations in Ricinus communis (Euphorbiaceae) under soil water stress conditions

Nonlinear Regression Models and Applications in Agricultural Research

Contact Info

Product

Resources

About