Elevated CO2 increases the leaf temperature of two glasshouse-grown C4 grasses

2002 ◽  
Vol 29 (12) ◽  
pp. 1377 ◽  
Author(s):  
Katharina Siebke ◽  
Oula Ghannoum ◽  
Jann P. Conroy ◽  
Susanne von Caemmerer

This study investigates the effect of elevated CO2 partial pressure (pCO2)-induced stomatal closure on leaf temperature and gas exchange of C4 grasses. Two native Australian C4 grasses, Astrebla lappacea (Lindl.) Domin and Bothriochloa bladhii Kuntze, were grown at three different pCO2 (35, 70 and 120 Pa) in three matched, temperature-controlled glasshouse compartments. The difference between leaf and air temperature (ΔT) was monitored diurnally with thermocouples. ΔT increased with both step-increases of ambient pCO2. Average noon leaf temperature increased by 0.4 and 0.3°C for A. lappacea with the 35–70 and 70–120 Pa steps of pCO2 elevation, respectively. For B. bladhii, the increases were 0.5°C for both pCO2 steps. ΔT was strongly dependent on irradiance, pCO2 and air humidity. Leaf gas exchange was measured at constant temperature and high irradiance at the three growth pCO2. Under these conditions, CO2 assimilation saturated at 70 Pa, while stomatal conductance decreased by the same extent (0.58-fold) with both step-increases in pCO2, suggesting that whole-plant water use efficiency of C4 grasses would increase beyond a doubling of ambient pCO2. The ratio of intercellular to ambient pCO2 was not affected by short- or long-term doubling or near-tripling of pCO2, in either C4 species when measured under standard conditions.


HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 476B-476
Author(s):  
John L. Jifon ◽  
Jim Syvertsen

Maximum CO2 assimilation rates (ACO2) in citrus are not realized in environments with high irradiance, high temperatures, and high leaf-to-air vapor pressure differences (D). We hypothesized that moderate shading would reduce leaf temperature and D, thereby increasing stomatal conductance (gs) and ACO2. A 61% reduction in irradiance under aluminum net shade screens reduced midday leaf temperatures by 8 °C and D by 62%. This effect was prominent on clear days when average midday air temperature and vapor pressure deficits exceeded 30 °C and 3 kPa. ACO2 and gs increased 42% and 104%, respectively, in response to shading. Although shaded leaves had higher gs, their transpiration rates were only 7% higher and not significantly different from sunlit leaves. Leaf water use efficiency (WUE) was significantly improved in shaded leaves (39%) compared to sunlit leaves due to the increase in ACO2. Early in the morning and late afternoon when irradiance and air temperatures were low, shading had no beneficial effect on ACO2 or other gas exchange characteristics. On cloudy days or when the maximum daytime temperature and atmospheric vapor pressure deficits were less than 30 °C and 2 kPa, respectively, shading had little effect on leaf gas exchange properties. The results are consistent with the hypothesis that the beneficial effect of radiation load reduction on ACO2 is related to improved stomatal conductance in response to lowered D.



2013 ◽  
Vol 51 (3) ◽  
pp. 419-428 ◽  
Author(s):  
T. Kalyar ◽  
S. Rauf ◽  
J. A. Teixeira da Silva ◽  
S. Haidar ◽  
Z. Iqbal




1995 ◽  
Vol 22 (3) ◽  
pp. 461 ◽  
Author(s):  
J Vadell ◽  
C Cabot ◽  
H Medrano

The effects of drought acclimation on the diurnal time courses of photosynthesis and related characters were studied in Trifolium subterraneum L. leaves during two consecutive late spring days. Leaf CO2 assimilation rate and transpiration rate followed irradiance variations in irrigated plants. Under drought, a bimodal pattern of leaf CO2 assimilation rate developed although stomatal conductance remained uniform and low. Instantaneous water-use efficiency was much higher in droughted plants during the early morning and late evening, while during the middle of the day it was close to the value of irrigated plants. Net carbon gain in plants under drought reached 40% of the carbon gain in irrigated plants with a significant saving of water (80%). Average data derived from midday values of leaf CO2 assimilation rates and instantaneous water-use efficiency did not provide good estimates of the daily carbon gain and water-use efficiency for droughted leaves. Coupled with the morphological changes as a result of acclimation to progressive drought, modifications of diurnal patterns of leaf gas exchange rates effectively contribute to a sustained carbon gain during drought. These modifications significantly improve water-use efficiency, mainly by enabling the plant to take advantage of morning and evening hours with high air humidity.



2002 ◽  
Vol 29 (4) ◽  
pp. 451 ◽  
Author(s):  
João P. Maroco ◽  
M. Lucília Rodrigues ◽  
Carlos Lopes ◽  
M. Manuela Chaves

The effects of a slowly-imposed drought stress on gas-exchange, chlorophyll a fluorescence, biochemical and physiological parameters of Vitis vinifera L. leaves (cv. Aragonez, syn. Tempranillo) growing in a commercial vineyard (South Portugal) were evaluated. Relative to well-watered plants (predawn water potential, ΨPD = –0.13 ± 0.01 MPa), drought-stressed plants (ΨPD = –0.97 ± 0.01 MPa) had lower photosynthetic rates (ca 70%), stomatal conductance, and PSII activity (associated with a higher reduction of the quinone A pool and lower efficiency of PSII open centres). Stomatal limitation to photosynthesis was increased in drought-stressed plants relative to well-watered plants by ca 44%. Modelled responses of net photosynthesis to internal CO2 indicated that drought-stressed plants had significant reductions in maximum Rubisco carboxylation activity (ca 32%), ribulose-1,5-bisphosphate regeneration (ca 27%), and triose phosphate (triose-P) utilization rates (ca 37%) relative to well-watered plants. There was good agreement between the effects of drought on modelled biochemical parameters, and in vitro activities of key enzymes of carbon metabolism, namely Rubisco, glyceraldehyde-3-phosphate dehydrogenase, ribulose-5-phosphate kinase and fructose-1,6-bisphosphate phosphatase. Quantum yields measured under both ambient (35 Pa) and saturating CO2 (100 Pa) for drought-stressed plants were decreased relative to well-watered plants, as well as maximum photosynthetic rates measured at light and CO2 saturating conditions (three times ambient CO2 levels). Although stomatal closure was a strong limitation to CO2 assimilation under drought, comparable reductions in electron transport, CO2 carboxylation, and utilization of triose-P capacities were also adaptations of the photosynthetic machinery to dehydration that slowly developed under field conditions. Results presented in this study confirm that modelling photosynthetic responses based on gas-exchange data can be successfully used to predict metabolic limitations to photosynthesis.





Irriga ◽  
2020 ◽  
Vol 25 (4) ◽  
pp. 677-682
Author(s):  
Adriana Cruz de Oliveira ◽  
Antonio Flavio Batista de Araujo ◽  
Claudivan Feitosa de Lacerda ◽  
Juvenaldo Florentino Canjá ◽  
Luciana Luzia Pinho ◽  
...  

INFLUÊNCIA DA IRRIGAÇÃO SUPLEMENTAR COM ÁGUAS RESIDUÁRIAS SOBRE AS TROCAS GASOSAS FOLIARES DO ALGODOEIRO   ADRIANA CRUZ DE OLIVEIRA1; ANTONIO FLAVIO BATISTA DE ARAUJO2; CLAUDIVAN FEITOSA DE LACERDA3; JUVENALDO FLORENTINO CANJÁ4; LUCIANA LUZIA PINHO5 E NAARA IORRANA GOMES SOUSA6     1 Mestranda no Programa de Pós-Graduação em Engenharia Agrícola, Departamento de Engenharia Agrícola, Universidade Federal do Ceará-UFC, Av. Mister Hull, s/n -Pici, Centro de Ciências Agrárias, Bloco 804, CEP: 60455-760, Fortaleza-CE, Brasil. E-mail: [email protected] 2 Doutorando no Programa de Pós-Graduação em Engenharia Agrícola, Departamento de Engenharia Agrícola, Universidade Federal do Ceará-UFC, Av. Mister Hull, s/n -Pici, Centro de Ciências Agrárias, Bloco 804, CEP: 60455-760, Fortaleza-CE, Brasil. E-mail: [email protected] 3 Professor Titular do Departamento de Engenharia Agrícola, Universidade Federal do Ceará-UFC, Av. Mister Hull, s/n -Pici, Centro de Ciências Agrárias, Bloco 804, CEP: 60455-760, Fortaleza-CE, Brasil. E-mail: [email protected] 4Mestrando no Programa de Pós-Graduação em Engenharia Agrícola, Departamento de Engenharia Agrícola, Universidade Federal do Ceará-UFC, Av. Mister Hull, s/n -Pici, Centro de Ciências Agrárias, Bloco 804, CEP: 60455-760, Fortaleza-CE, Brasil. E-mail: [email protected] 5 Mestranda no Programa de Pós-Graduação em Engenharia Agrícola, Departamento de Engenharia Agrícola, Universidade Federal do Ceará-UFC, Av. Mister Hull, s/n -Pici, Centro de Ciências Agrárias, Bloco 804, CEP: 60455-760, Fortaleza-CE, Brasil. E-mail: [email protected] 6 Mestranda no Programa de Pós-Graduação em Engenharia Agrícola, Departamento de Engenharia Agrícola, Universidade Federal do Ceará-UFC, Av. Mister Hull, s/n -Pici, Centro de Ciências Agrárias, Bloco 804, CEP: 60455-760, Fortaleza-CE, Brasil. E-mail: [email protected]     1 RESUMO   O uso de águas residuárias na irrigação tem crescido como suplementação para driblar a escassez hídrica. Contudo, pouco se sabe sobre as respostas das culturas sobre sua aplicação. Assim, objetivou-se avaliar os impactos da irrigação suplementar com águas residuárias tratadas sobre as trocas gasosas do algodoeiro (Gossypium hirsutum L), simulando-se cenários hídricos considerados normais, seca e seca severa, na presença e ausência de NPK. O experimento foi conduzido no município de Russas – CE, em área vizinha à lagoa de estabilização da CAGECE – Companhia de Água e Esgoto do Estado do Ceará, em DBC, no esquema de parcelas subsubdivididas, com quatro blocos. As parcelas foram cenários hídricos (normal, seca e seca severa); a subparcela foi a suplementação ou não com água residuária tratada nos veranicos simulados; a subsubparcela foi a aplicação ou não de NPK. A cultivar utilizada foi BR 433. Aos 25 dias após a semeadura foram analisadas fotossíntese, transpiração, concentração interna de CO2 e temperatura foliar. Os cenários de seca e seca severa apresentaram pequeno impacto sobre as trocas gasosas foliares do algodoeiro. Entretanto, a irrigação suplementar reduziu a temperatura foliar e atenuou os efeitos do cenário de seca sobre a fotossíntese, independente da aplicação ou não de NPK.   Palavras-chave: Gossypium hirsutum L, Reúso de água, Seca.         OLIVEIRA, A. C. de; ARAUJO, A. F. B. de; LACERDA, C. F. de; CANJÁ, J. F.; PINHO, L. L.; SOUSA, N. I. G. INFLUENCE OF SUPPLEMENTAL IRRIGATION WITH WASTEWATER ON COTTON LEAF GAS EXCHANGE     2 ABSTRACT   The use of wastewater in irrigation has grown as a supplement to circumvent water scarcity. However, little is known about the responses of cultures to its application. Thus, the objective was to evaluate the impacts of supplementary irrigation with treated wastewater on gas exchange of cotton (Gossypium hirsutum L), simulating water scenarios considered normal, drought and severe drought, in the presence and absence of NPK. The experiment was conducted in the municipality of Russas - CE, in an area next to the stabilization pond of CAGECE - Companhia de Agua e Esgoto do Estado do Ceará, in DBC, in the subdivided plot scheme, with four blocks. The plots were water scenarios (normal, drought and severe drought); the subplot was supplemented or not with wastewater treated in the simulated summer days; the sub-installment was the application or not of NPK. The cultivar used was BR 433. At 25 days after sowing, photosynthesis, transpiration, internal CO2 concentration and leaf temperature were analyzed. The drought and severe drought scenarios had little impact on the cotton leaf gas exchange. However, supplementary irrigation reduced leaf temperature and attenuated the effects of drought scenario on photosynthesis, whether or not NPK was applied.   Keywords: Gossypium hirsutum L, Water reuse, Drought.



2020 ◽  
Author(s):  
Karla Gasparini ◽  
Ana Carolina R. Souto ◽  
Mateus F. da Silva ◽  
Lucas C. Costa ◽  
Cássia Regina Fernandes Figueiredo ◽  
...  

ABSTRACTBackground and aimsTrichomes are epidermal structures with an enormous variety of ecological functions and economic applications. Glandular trichomes produce a rich repertoire of secondary metabolites, whereas non-glandular trichomes create a physical barrier against biotic and abiotic stressors. Intense research is underway to understand trichome development and function and enable breeding of more resilient crops. However, little is known on how enhanced trichome density would impinge on leaf photosynthesis, gas exchange and energy balance.MethodsPrevious work has compared multiple species differing in trichome density, instead here we analyzed monogenic trichome mutants in a single tomato genetic background (cv. Micro-Tom). We determined growth parameters, leaf spectral properties, gas exchange and leaf temperature in the hairs absent (h), Lanata (Ln) and Woolly (Wo) trichome mutants.Key resultsShoot dry mass, leaf area, leaf spectral properties and cuticular conductance were not affected by the mutations. However, the Ln mutant showed increased carbon assimilation (A) possibly associated with higher stomatal conductance (gs), since there were no differences in stomatal density or stomatal index between genotypes. Leaf temperature was furthermore reduced in Ln in the early hours of the afternoon.ConclusionsWe show that a single monogenic mutation can increase glandular trichome density, a desirable trait for crop breeding, whilst concomitantly improving leaf gas exchange and reducing leaf temperature.HIGHLIGHTA monogenic mutation in tomato increases trichome density and optimizes gas exchange and leaf temperature



1975 ◽  
Vol 53 (5) ◽  
pp. 475-482 ◽  
Author(s):  
H. S. Srivastava ◽  
P. A. Jolliffe ◽  
V. C. Runeckles

An open flow system was used to examine the uptake and effects of NO2 on gas exchange by primary leaves of bean (Phaseolus vulgaris L.) under a variety of conditions of irradiance, temperature, humidity, and atmospheric CO2 and O2 concentrations. At 3.0 ppm, NO2 inhibited apparent photosynthesis and dark respiration in all the conditions tested. Both 3.0 ppm and 7.0 ppm NO2 inhibited the evolution of CO2 into CO2-free air. The absolute magnitude of photosynthetic inhibition by NO2 was greatest at high irradiance, at the optimum temperature for apparent photosynthesis, and at high humidities. Changes in CO2 concentration from 100 to 600 ppm and in O2 concentration from 0 to 21% did not affect the percentage inhibition of apparent photosynthesis by NO2. High temperatures increased the inhibitory effects of NO2 on dark respiration.The effects of NO2 on apparent photosynthesis, dark respiration, and CO2 evolution into CO2-free air were based on inhibitory effects exerted within the leaves and not on CO2 diffusion into the leaf. Transpiration rate and stomatal diffusion resistance were only slightly affected by NO2. The uptake of NO2 was enhanced by high temperature, low CO2 concentration, and high humidity. The results of these studies support the view that NO2 uptake is subject to internal limitations ("mesophyll resistance") under many environmental conditions.The range and prevalence of NO2 effects suggest that NO2 may cause general detrimental changes in the physiology of leaf cells. Furthermore, the circumstances under which NO2 effects were found to occur indicate that such effects may be significant in natural ecosystems.



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