Topography of Photosynthetic Activity of Leaves Obtained from Video Images of Chlorophyll Fluorescence

Daley, Paul F.; Raschke, Klaus; Ball, J. Timothy; Berry, Joseph A.

doi:10.1104/pp.90.4.1233

Cited by 192 publications

(120 citation statements)

References 22 publications

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“…Porém esse mecanismo de fechamento estomático não acarretou em diferenças significativas para a eficiência do uso da água entre as cultivares (Tabela 2). Daley et al (1989) relatam que a redução da condutância estomática pode limitar a taxa de retenção de CO 2 e, consequentemente, a concentração Ci diminui nos espaços intercelulares devido ao consumo de CO 2 pela atividade fotossintética.…”

Section: Resultsunclassified

Trocas gasosas e produtividade de três cultivares de meloeiro conduzidas com um e dois frutos por planta

et al. 2014

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ResumoObjetivou-se, no presente trabalho, avaliar as trocas gasosas e sua influência na produtividade e qualidade de cultivares de melão conduzidas com um e dois frutos por planta. O experimento foi conduzido de setembro a dezembro de 2013. Utilizouse o delineamento de blocos ao acaso, em esquema fatorial 3 x 2, com seis repetições. No primeiro fator foram alocadas as cultivares de melão pertencentes aos tipos amarelo, rendilhado e pele de sapo e no segundo fator, a condução das plantas com um e dois frutos por planta. Foram utilizadas três cultivares de melão para cada tipo. As avaliações foram realizadas aos 40 e aos 56 dias após o transplantio. As características avaliadas foram: taxa de assimilação líquida de CO 2 (A), transpiração foliar (E), condutância estomática (g s ) e concentração interna de CO 2 (C i ). A partir dessas medidas foi calculada a eficiência no uso da água (WUE). O teor de sólidos solúveis foi determinado por leitura direta, enquanto que a massa média dos frutos foi mensurada no momento da colheita, estimando-se a produtividade. Diante dos resultados, pode-se concluir que as diferenças nos índices de trocas gasosas para as cultivares de melão do tipo pele de sapo não influenciaram na produtividade e no teor de sólidos solúveis. Como melão do tipo amarelo e do tipo rendilhado recomendam-se as cultivares Goldex e Louis, respectivamente. Independente da cultivar, recomenda-se o cultivo de melão com dois frutos por planta, por assim as plantas apresentarem maior produtividade sem alterar de forma expressiva os índices de trocas gasosas delas.Palavras-chave: Cucumis melo L., taxa assimilatória líquida de CO 2 , transpiração, condutância estomática, eficiência no uso da água.Gas exchange and productivity from three cultivars of melon conduced with one and two fruit per plant AbstractThe objective of the present work was to evaluate gas exchange and its influence on productivity and quality of melon cultivars conducted with one and two fruits per plant. The experiment was conducted from September to December, 2013. The experimental design was of randomized blocks in factorial design 3 x 2 with six replications. In the first factor were allocated the melon cultivars, belonging to types canary melon, net melon and frog skin melon; and the second factor was the conduction of plants with one and two fruits per plant. Three melon cultivars were used for each type. The evaluations were performed at 40 and 56 days after transplanting. The characteristics evaluated were: CO 2 assimilation rate (A), transpiration (E), stomatic conductance (gs), the internal CO 2 concentration (Ci). From these measurements was calculated water use efficiency (EUA). The soluble solids content was determined by direct reading, while the average fruit weight was measured at harvest, estimating productivity. With the results, it can be concluded that differences in gas exchange indexes to cultivars of frog skin melon type have no influence on productivity and soluble solids content. To cultivars of canary melon and net melon ...

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Section: Resultsunclassified

Trocas gasosas e produtividade de três cultivares de meloeiro conduzidas com um e dois frutos por planta

et al. 2014

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“…Images of chlorophyll fluorescence were acquired and analysed as described previously (Daley et al 1989;Mott 1995), Briefly, a leaf in a gas-exchange chatnber was illuminated with light filtered to remove wavelengths above 700 nm. The leaf was exposed to 1 s pulses of high light (PFD = =5000 ^umol nT^ s~' also filtered to remove wavelengths above 700 nm) at regular ititervals.…”

Section: Methodsmentioning

confidence: 99%

A spatially explicit model of patchy stomatal responses to humidity

Haefner

Buckley

Mott

1997

Plant Cell & Environment

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Stomata of leaves can exhibit either temporally stable, spatially homogeneous behaviour or complex spatial and temporal dynamics, depending on environmental and physiological conditions. To test the ability of accepted physiological mechanisms to describe these patterns, we developed a simple, spatially explicit model of stomatal responses to humidity that incorporated hydraulic interactions among stomata. Model results showed qualitative agreement with experimental evidence for a number of phenomena: (1) at high humidities, whole-leaf steady-state conductance is a monotonic function of humidity; (2) the initial stomatal response following a perturbation in humidity is in the direction opposite to the final response, and (3) spatial dynamics include patch formation and selforganization similar to that observed in actual leaves. These comparisons do not eliminate other explanations, but do suggest that novel mechanisms need not be invoked to explain the diversity of spatial and temporal patterns of stomatal behaviour in leaves.

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“…communication, 1989) has a didactic modcl to explain the apparent constancy of ci for a "patchyncss" of 50%. Of course the pattern of patchyness is more complex as Daley et al (1989) a) The interaction bctwcen the determinants of p and s.…”

Section: Thying To Remove a Contradictionmentioning

confidence: 99%

“…carboxilation inhibition) or a putchyncss occurcncc. As fluorescence techniques are cspccially appropriate to study str·css-induccd problcms, as Raschkc pointcd out (Daley et al, 1989) they should he comhincd with G EMin carring out this kind of studies (Jones, persona! communication).…”

Section: So To Maintain C Constant When Stomatal Resistance (And Somentioning

confidence: 99%

“…A decade ago a sophistieated thcory, whcre stand out the names of Cowan and Farquhar (Wong et al, 1979 ;Farquhar et al, 1982), claimed that p is, in general, of grcatcr magnitude than s (p > > s) and that the effeet of drought on the mcsophyll commanded, to a large extent, the degree of stomatal opening. Ilowevcr, evidence gathcred from recent studics (Kaiser, 1987 ;Cornic, 1989 ;Daley et al, 1989) and, in particular, the discovery of "patchyness" on induced stomatal closure, raised the possibility of an alternative explanation.…”

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Protoplasmic drought resistance and water use efficiency

Moreira

Henriques

Matos

et al. 1990

Bulletin de la Société Botanique de France. Actualités Botaniqu

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Summary.· When water is limiting plant growth, will il be essential to increase protoplasmic drought resistance (PDR) in arder to improve water use efficiency (WUE) ? Such subject is obviously of utmost importance for semi·arid tropical and mediterranean zones.Water deficit brings a decrease (d) to net photosynthetic rate (A) by means of a "stomatal" (s) and/or a, so-called, "non-stomatal" effect (p). Disregarding miner factors, one can write : d = A 0 ·A, = s + p + i where i represents the interaction between the determinant factors of s and p, and A 0 and A, are the values of A belo re and alter drought stress.Since the remarkable work of Cowan and Farquhar, at the beginning of the eighties il was almost generally accepted thal p >>s.But the discovery of a "patchyness" phenomenon on induced stomatal closure, raised the possibility of a different perspective.We will tackle the problem und er discussion as !ollows : 1) General formulation : The deterministic chain involving s, p, and their determinants is designed. The interaction factor i is necessary in this context. 2) As water deficit progresses, when does p begin to become important ? ls it also important under field agricultural conditions ?Experimental results embodied in a !ramework give the answer to such questions : s cames normally tirs\ ; for C3 plants p becomes critical just for Relative Water Deficit (RWD) valves higher !han the critical "Kaiser bell" (30 · 40 % RWD). Evidence is presented about the agricultural and ecological importance of p in the above mentioned climatic zones.3) Searching for an intrinsic index for the degree of protoplasmic strain: Can c, (the internai C0 2 concentration in the Cowan's sense) be used as such an index? Il will be demonstrated thal Ci = (r 2 + o) A +r 2 R, where r 2 is a quasi·ohmic resistance to the C0 2 flux from the point of effective junction of the C0 2 respiratory flow (the intensity of which is given by R) to the photosynthetic one, and o an anatomical resis· tance. lt is now obvious thal c, is tao ambiguous to be used as the searched index. We propose, instead, that such index can be played by r 2 thal includes the addition in series of the carboxilating and photoreducing resistances.4) Considering patchyness, we present tirs\ the Cornic's view on this matter and consider next the contribution of thal phenomenon in explaining the commonly accepted view of a secondary role of stomata in the decrease d caused by drought on photosynthesis. But the interaction i, usually !orgotten in this kind of studies, must also be considered. (i is generally negative). Other possible causes are discussed. A simple diaggnosis method for the detection of patchyness wh en RWD < 30 · 40% will be proposed. 5) Our work with Myrothamnus flabelifolia (a "ressurrection" plant) sheds seme light into this discussion. Plants with PDR have no need to re-build drought strained structures, but just to reactivate them by re·hydration. We try to design a quantitative criterion for PDR.6) Under heavy drought stress conditions to improve W...

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Topography of Photosynthetic Activity of Leaves Obtained from Video Images of Chlorophyll Fluorescence

Cited by 192 publications

References 22 publications

Trocas gasosas e produtividade de três cultivares de meloeiro conduzidas com um e dois frutos por planta

Trocas gasosas e produtividade de três cultivares de meloeiro conduzidas com um e dois frutos por planta

A spatially explicit model of patchy stomatal responses to humidity

Protoplasmic drought resistance and water use efficiency

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