Variações da temperatura foliar do dossel e o seu efeito na taxa assimilatória de CO2 na Amazônia Central.

Tribuzy, Edgard Siza

doi:10.11606/t.91.2005.tde-15072005-144011

Cited by 25 publications

(29 citation statements)

References 71 publications

(107 reference statements)

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“…According to Tribuzy (2005), the increase in leaf temperature, during fruit ripening, might alter the structure of the enzymes involved in the carboxylation stage, as well as increase the fluidity of the chloroplast membranes, which directly affects the net carbon assimilation. Hence, both the biochemical process and CO 2 fixation are damaged by increased leaf temperature.…”

Section: Resultsmentioning

confidence: 99%

Physiological and biochemical characterization of mango tree with paclobutrazol application via irrigation1

Souza

Mésquita

Simões

et al. 2016

Pesqui. Agropecu. Trop.

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Paclobutrazol application in mango tree floral induction is followed by changes in the hormonal balance and carbohydrates production. This study aimed at evaluating the physiological and biochemical variables of mango tree (Palmer cultivar) by applying paclobutrazol doses via irrigation. The experimental design was randomized blocks, with five paclobutrazol doses (0.7 g, 1.0 g, 1.3 g, 1.6 g and 1.9 g of a.i. per linear meter of canopy) and one additional treatment, with one dose in the conventional form of application (1.9 g of a.i. per linear meter of canopy), and four replicates. The variables analyzed were: photosynthesis rate; stomatal conductance; transpiration; leaf temperature; CO2 ratio; total protein content; reducing, non-reducing and total soluble sugars in leaf tissue and fruit; and nitrate reductase enzyme. The lowest values for photosynthesis rate and stomatal conductance were obtained with paclobutrazol applied via irrigation. The highest values for gas exchange were obtained with the lowest paclobutrazol doses applied via irrigation, showing that this kind of application is efficient and that it is possible to reduce the application dose via irrigation system. The highest carbohydrate contents in the leaf tissue were observed for the doses of 1.06 g and 1.09 g of a.i. per linear meter of canopy, applied via irrigation. The carbohydrate contents in fruits decreased in response to the paclobutrazol dose. The application methods and doses applied via irrigation did not influence the nitrate reductase activity.

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Section: Resultsmentioning

confidence: 99%

Physiological and biochemical characterization of mango tree with paclobutrazol application via irrigation1

Souza

Mésquita

Simões

et al. 2016

Pesqui. Agropecu. Trop.

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“…Apesar de não serem observadas diferenças significativas entre as taxas de transpiração para essa situação, tem-se considerado que a transpiração desempenha papel importante na regulação da temperatura foliar, impedindo que esta atinja níveis letais para as plantas (TRIBUZY, 2005).…”

Section: Resultsunclassified

Respostas de variáveis fisiológicas e tecnológicas da cana-de-açúcar a diferentes sistemas de irrigação1

Simões¹,

Calgaro²,

Coelho³

et al. 2015

Rev. Ciênc. Agron.

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RESUMO -O objetivo do trabalho foi avaliar a influência de três sistemas de irrigação sobre as trocas gasosas e as qualidades tecnológicas da cana-de-açúcar, variedade RB 92579, por três ciclos consecutivos, cultivada em dois tipos de solos na região do Submédio do São Francisco. Os experimentos foram instalados utilizando delineamento experimental em blocos casualizados, com seis repetições, em áreas com solo arenoso e argiloso. Os sistemas de irrigação foram: sulco, gotejamento superficial e gotejamento subsuperficial. Avaliaram-se as características fisiológicas das plantas: fotossíntese líquida, condutância estomática, transpiração e temperatura foliar. Para análises tecnológicas foram determinados o teor de sólidos solúveis, porcentagem de fibra industrial, pureza do caldo, porcentagem de açúcar bruto, açúcares redutores e umidade. Verificou-se que a irrigação por gotejamento subsuperficial em solo arenoso interfere negativamente nas trocas gasosas da cultura. Os sistemas de irrigação não influenciaram na qualidade tecnológica dos colmos quando cultivada em solo arenoso e, no argiloso, o sulco interfere negativamente no processo de maturação dos colmos. Palavras-chave:ABSTRACT -The aim of this study was to evaluate the influence of three irrigation systems on the gas exchange and technological qualities of the sugarcane variety RB 92579, for three consecutive cycles, grown in two types of soil in the Lower Basin region of San Francisco in Brazil. The experiments were set up in a randomised-block design, with six replications, in areas of sandy and clayey soil. The irrigation systems used were: furrow, surface drip and subsurface drip. The following physiological characteristics of the plants were evaluated: net photosynthesis, stomatal conductance, transpiration and leaf temperature. In the technological analyses, levels were determined for soluble solids, percentage of industrial fibre, juice purity, percentage of raw sugar, reducing sugars and moisture. It was found that subsurface drip irrigation in sandy soil impairs the gas exchange of the crop. The irrigation systems did not influence the technological quality of the stalks when grown in sandy soil. In clay soil, furrow irrigation impairs the maturation process of the stems.

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“…Field observations have drawn attention to the possibility that tropical forest production is highly sensitive to temperature [ Clark et al , 2003; Feeley et al , 2007]. Studies of leaf gas exchange using chambers have found that photosynthesis by tropical leaves declines above 26 to 34°C [ Koch et al , 1994; Ishida et al , 1999; Keller and Lerdau , 1999; Lerdau and Throop , 1999; Graham et al , 2003; Tribuzy , 2005]. Sunlit canopy leaves in tropical forests may be several °C above air temperature [ Ishida et al , 1999; Leakey et al , 2003; Tribuzy , 2005], implying that photosynthesis is sometimes constrained by high temperatures.…”

Section: Introductionmentioning

confidence: 99%

“…Studies of leaf gas exchange using chambers have found that photosynthesis by tropical leaves declines above 26 to 34°C [ Koch et al , 1994; Ishida et al , 1999; Keller and Lerdau , 1999; Lerdau and Throop , 1999; Graham et al , 2003; Tribuzy , 2005]. Sunlit canopy leaves in tropical forests may be several °C above air temperature [ Ishida et al , 1999; Leakey et al , 2003; Tribuzy , 2005], implying that photosynthesis is sometimes constrained by high temperatures. Field measurements of whole‐ecosystem CO 2 exchange in tropical forests made using the eddy covariance technique indicate that CO 2 uptake decreases markedly during warmer than average periods [ Loescher et al , 2003; Goulden et al , 2004].…”

Section: Introductionmentioning

confidence: 99%

Are tropical forests near a high temperature threshold?

2008

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[1] We used leaf gas exchange, sap flow, and eddy covariance measurements to investigate whether high temperature substantially limits CO 2 uptake at the LBA-ECO (Large-scale Biosphere-Atmosphere) km-83 tropical forest site in Brazil. Leaf-level temperature-photosynthesis curves, and comparisons of whole-canopy net ecosystem CO 2 exchange (NEE) with air temperature, showed that CO 2 uptake declined sharply during warm periods. Observations of ambient leaf microclimate showed that leaves oscillate between two states: a cool, dimly lit stage and a hot, brightly illuminated stage where leaf temperatures are often greater than 35°C. The leaf-level rates of photosynthesis decreased when shaded leaves ($ambient air temperature and < 500 mmol m À2 s À1 ) were transferred into a prewarmed, brightly illuminated chamber (35°to 38°C and 1000 mmol m À2 s À1 ), coincident with increased leaf temperature, increased evaporative demand, and stomatal closure. The rates of whole-canopy CO 2 uptake calculated at 5-min intervals increased initially at the onset of sunny periods that followed extended cloudy periods, but then decreased as the sunlight continued, leaf temperature and evaporative demand increased, and canopy conductance decreased. The forest at km-83 appears to be close to a high temperature threshold, above which CO 2 uptake drops sharply. This sensitivity results in part from the covariance between leaf temperature and leaf illumination; the brightly illuminated leaves that contribute disproportionately to canopy photosynthesis are warmed to the point that leaf gas exchange is curtailed.

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Variações da temperatura foliar do dossel e o seu efeito na taxa assimilatória de CO2 na Amazônia Central.

Cited by 25 publications

References 71 publications

Physiological and biochemical characterization of mango tree with paclobutrazol application via irrigation1

Physiological and biochemical characterization of mango tree with paclobutrazol application via irrigation1

Respostas de variáveis fisiológicas e tecnológicas da cana-de-açúcar a diferentes sistemas de irrigação1

Are tropical forests near a high temperature threshold?

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Variações da temperatura foliar do dossel e o seu efeito na taxa assimilatória de CO2 na Amazônia Central.

Cited by 25 publications

References 71 publications

Physiological and biochemical characterization of mango tree with paclobutrazol application via irrigation1

Physiological and biochemical characterization of mango tree with paclobutrazol application via irrigation1

Respostas de vari&#225;veis fisiol&#243;gicas e tecnol&#243;gicas da cana-de-a&#231;&#250;car a diferentes sistemas de irriga&#231;&#227;o1

Are tropical forests near a high temperature threshold?

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Respostas de variáveis fisiológicas e tecnológicas da cana-de-açúcar a diferentes sistemas de irrigação1