Assimilate Source-Sink Relationships in Capsicum annuum L. III. The Effects of Fruit Excision on Photosynthesis and Leaf and Stem Carbohydrates.

1978 ◽  
Vol 5 (1) ◽  
pp. 1 ◽  
Author(s):  
AJ Hall ◽  
FL Milthorpe
Keyword(s):  
Control Mechanism ◽  
Dark Respiration ◽  
Soluble Sugars ◽  
Co2 Concentration ◽  
Co2 Uptake ◽  
Factors Affecting ◽  
Co2 Compensation Point ◽  
Time Period ◽  
Internal Co2 ◽  
Source Sink

Removal of the rapidly growing fruit from a Capsicum plant reduced the rate of net CO2 uptake by its leaves by up to 30% during the time period explored (0.5 - 7 days). This reduction was associated with increases in both the leaf (to about 200%) and intracellular (to about 30%) resistances, these changes having about equal effects on reducing the rate of CO2 uptake. Changes in photorespiration, dark respiration and CO2 compensation point were very small. The rate of CO2 uptake and the associated resistances were also changed by modifying the light regime and other factors affecting the source-sink balance. Changes in the leaf resistance were not attributable to variations in the internal CO2 concentration or in the water economy of the leaf; its control mechanism remains unexplained. The concentration of soluble sugars in the source leaf was completely unaffected but that of polysaccharides was changed by defruiting and by 50% defoliation. However, variations in the intracellular resistance were not closely related to these changes and there is yet no evidence of the nature of its control mechanism. Changes in both soluble sugars and polysaccharides in the stem were more pronounced than in the leaves.

Opposite changes in leaf dark respiration and soluble sugars with drought in two Mediterranean oaks

2011 ◽  
Vol 38 (12) ◽  
pp. 1004 ◽  
Author(s):  
Jesús Rodríguez-Calcerrada ◽  
Oula Shahin ◽  
María del Carmen del Rey ◽  
Serge Rambal
Keyword(s):  
Water Deficit ◽  
Dark Respiration ◽  
Leaf Gas Exchange ◽  
Soluble Sugars ◽  
Water Deficit Stress ◽  
Co2 Uptake ◽  
Opposite Pattern ◽  
Leaf Dark Respiration ◽  
Mediterranean Oaks ◽  
Relative Production

The decline in net photosynthetic CO2 uptake (An) caused by drought could reduce the availability of soluble sugars and thus limit leaf dark respiration (Rd). We investigated the response of leaf gas exchange and nonstructural carbohydrates to drought by stopping watering to 2-year-old plants of Quercus ilex L. and Quercus pubescens Willd. grown in large pots. An declined with increasing water deficit more rapidly than Rd, and Rd declined slightly more steeply in Q. ilex than in Q. pubescens. Soluble sugars increased in drought-treated plants relative to control well watered plants, and the opposite pattern was found for starch. After rewatering, Rd returned to pre-drought rates within 2 days and An within 1 week. Soluble sugars tended to recover pre-drought values after rewatering but continued to be significantly higher in drought-treated than control plants of Q. pubescens, for which the increase in the concentration of soluble sugars had been higher. These results suggest that the relative production of soluble sugars is upregulated when An is limited, and that soluble sugars do not control respiratory rates in response to and recovery from water deficit. Rather, we suggest that the decline in Rd contributes to drought tolerance by reducing the consumption of soluble sugars, which play an important role as osmoprotectants during water deficit stress.

Enhancing biomass production and yield by maintaining enhanced capacity for CO2 uptake in response to elevated CO2

2014 ◽  
Vol 94 (6) ◽  
pp. 1075-1083 ◽  
Author(s):  
Keshav Dahal ◽  
Sarathi M. Weraduwage ◽  
Khalil Kane ◽  
Shezad A. Rauf ◽  
Evangelos D. Leonardos ◽  
...  
Keyword(s):  
Biomass Production ◽  
Acid Metabolism ◽  
Dark Respiration ◽  
Co2 Uptake ◽  
Canopy Photosynthesis ◽  
Acclimation Response ◽  
Sink Development ◽  
Source Sink ◽  
Primary Substrate

Dahal, K., Weraduwage, S. M., Kane, K., Rauf, S. A., Leonardos, E. D., Gadapati, W., Savitch, L., Singh, J., Marillia, E.-F., Taylor, D. C., Micallef, M. C., Knowles, V., Plaxton, W., Barron, J., Sarhan, F., Hüner, N., Grodzinski, B. and Micallef, B. J. 2014. Enhancing biomass production and yield by maintaining enhanced capacity for CO2 uptake in response to elevated CO2. Can. J. Plant Sci. 94: 1075–1083. Using four model plants, two members of the Gramineae, rye and wheat, and two Brassicaceae, Brassica napus and Arabidopsis thaliana, two fundamental approaches were exploited to determine how regulating source-sink development would alter photosynthesis, productivity and yield during long-term acclimation to elevated CO2. In one approach we exploited the cold acclimation response of winter wheat, rye and B. napus. In the other approach we modified the dark respiration in A. thaliana to alter availability of respiratory substrates required for anabolic processes, such as fatty acid metabolism, thus reducing sink limitations on canopy photosynthesis at elevated CO2. Taken together, the data show the importance of maintaining strong demand from active sinks when the above-ground canopy is being exposed to elevated levels of the primary substrate of photosynthesis, CO2.

GENETIC AND OTHER FACTORS AFFECTING INTERNAL CO2 CONCENTRATION IN SUGAR BEET ROOTS

1976 ◽  
Vol 56 (3) ◽  
pp. 627-631 ◽  
Author(s):  
D. F. COLE ◽  
W. M. BUGBEE
Keyword(s):  
Genetic Variation ◽  
Sugar Beet ◽  
Storage Temperature ◽  
Co2 Concentration ◽  
Coefficient Of Determination ◽  
Root Weight ◽  
Factors Affecting ◽  
Internal Co2 Concentration ◽  
Temperature Decay ◽  
Internal Co2

Studies were conducted to determine if there was genetic variation in internal CO2 levels in sugar beet roots during storage and to determine the effects of resident bacteria, storage temperature, decay, and root weight on internal CO2 levels. Significant differences in internal CO2 levels were observed among different sugar beet lines. Internal CO2 levels of roots selected from American 3 Hybrid T were not correlated with the number of resident bacteria or weight of the roots after two storage periods. Root weight was negatively correlated with internal CO2 over all lines and the coefficient of determination was 2.2% (r2 × 100). Internal CO2 levels in roots with visible decay were significantly higher (5.21%) than CO2 levels (1.92%) in healthy roots. Higher storage temperature significantly increased internal CO2 levels in sugar beet roots. Our results show that there is genetic variation for internal CO2 levels in sugar beet roots.

Photosynthetic Oxygen Exchange in Attached Leaves of C4 Monocotyledons

1982 ◽  
Vol 9 (5) ◽  
pp. 553 ◽  
Author(s):  
RT Furbank ◽  
MR Badger
Keyword(s):  
Malic Enzyme ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Co2 Concentration ◽  
O2 Evolution ◽  
Co2 Uptake ◽  
O2 Uptake ◽  
Co2 Compensation Point ◽  
Uptake Rates ◽  
Photosynthetic O2 Evolution ◽  
Photosynthetic Oxygen

Photosynthetic O2 evolution, O2 uptake and CO2 uptake by intact leaves from plants of the three C4 decarboxylation types were examined using mass-spectrometric gas-exchange and stable isotope techniques. All species showed a relative insensitivity of O2 uptake to CO2 concentration. The uptake rates observed were between 0.2 and 1 nmol O2 cm-2 S-1 at the CO2 compensation point. At ambient external CO2, NADP-malic enzyme type species showed the lowest average O2 uptake, phosphoenolpyruvate carboxykinase types the highest values, and NAD-malic enzyme types showed intermediate values for O2 uptake. These results are discussed in relation to the contributions to O2 uptake of ribulosebisphosphate oxygenase and photoreduction of oxygen.

scholarly journals Diverse Banana Pseudostems and Rachis Are Distinctive for Edible Carbohydrates and Lignocellulose Saccharification towards High Bioethanol Production under Chemical and Liquid Hot Water Pretreatments

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3870
Author(s):  
Jingyang Li ◽  
Fei Liu ◽  
Hua Yu ◽  
Yuqi Li ◽  
Shiguang Zhou ◽  
...  
Keyword(s):  
Soluble Sugars ◽  
Enzymatic Saccharification ◽  
Hot Water ◽  
Biofuel Production ◽  
Bioenergy Crops ◽  
Bioethanol Production ◽  
Factors Affecting ◽  
Liquid Hot Water ◽  
Biomass Processing ◽  
Banana Crops

Banana is a major fruit crop throughout the world with abundant lignocellulose in the pseudostem and rachis residues for biofuel production. In this study, we collected a total of 11 pseudostems and rachis samples that were originally derived from different genetic types and ecological locations of banana crops and then examined largely varied edible carbohydrates (soluble sugars, starch) and lignocellulose compositions. By performing chemical (H2SO4, NaOH) and liquid hot water (LHW) pretreatments, we also found a remarkable variation in biomass enzymatic saccharification and bioethanol production among all banana samples examined. Consequently, this study identified a desirable banana (Refen1, subgroup Pisang Awak) crop containing large amounts of edible carbohydrates and completely digestible lignocellulose, which could be combined to achieve the highest bioethanol yields of 31–38% (% dry matter), compared with previously reported ones in other bioenergy crops. Chemical analysis further indicated that the cellulose CrI and lignin G-monomer should be two major recalcitrant factors affecting biomass enzymatic saccharification in banana pseudostems and rachis. Therefore, this study not only examined rich edible carbohydrates for food in the banana pseudostems but also detected digestible lignocellulose for bioethanol production in rachis tissue, providing a strategy applicable for genetic breeding and biomass processing in banana crops.

Adaptive responses to drought of two Retama raetam subspecies from Tunisia

2021 ◽  
Author(s):  
Ricardo GIL ◽  
Dhikra ZAYOUD ◽  
Zeineb OUERGHI ◽  
Monica BOSCAIU ◽  
Oscar VICENTE ◽  
...  
Keyword(s):  
Drought Stress ◽  
Glycine Betaine ◽  
Soluble Sugars ◽  
Co2 Concentration ◽  
Photosynthetic Parameters ◽  
Adaptive Responses ◽  
Retama Raetam ◽  
Physiological Adaptations ◽  
Use Efficiency ◽  
Desert Climate

Abstract Aims The survival and ecological distribution of plants in arid habitats are mainly conditioned by water availability and physiological adaptations to withstand drought. In the present study, we have compared the physiological responses to drought of two Retama raetam (retama) subspecies from Tunisia, one of them living under the desert climate (subsp. raetam) and the other one growing on the coast (subsp. bovei). Methods To physiologically characterize the two R. raetam subspecies, and to elucidate their main mechanisms underlying their tolerance to drought stress, parameters related to seed germination, growth, photosynthesis (net photosynthetic rate, intracellular CO2 concentration, transpiration rate, stomatal conductance and water use efficiency), and accumulation of osmolytes (proline, glycine betaine and soluble sugars) were determined in four-month-old plants subjected to stress for up to one month. Important findings Drought significantly inhibited germination, growth, and all the evaluated photosynthetic parameters. Plants of R. raetam subsp. bovei were severely affected by drought after three weeks of treatment when photosynthesis rates were up to 7-fold lower than in the controls. At the same time, proline and glycine betaine significantly accumulated compared to the irrigated controls, but much less than in R. raetam subsp. raetam; in the latter subspecies, proline and glycine betaine increased to levels 24-fold and 6-fold higher, respectively, than in the corresponding controls. In summary, the population living in the desert region exhibited stronger tolerance to drought stress than that adapted to the semiarid littoral climate, suggesting that tolerance in R. raetam is dependent on accumulation of osmolytes.

scholarly journals Immobilized Microalgae-Based Photobioreactor for CO2 Capture (IMC-CO2PBR): Efficiency Estimation, Technological Parameters, and Prototype Concept

Atmosphere ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1031
Author(s):  
Marcin Dębowski ◽  
Mirosław Krzemieniewski ◽  
Marcin Zieliński ◽  
Joanna Kazimierowicz
Keyword(s):  
Carbon Dioxide Emissions ◽  
Functional Model ◽  
Biomass Concentration ◽  
Co2 Concentration ◽  
Ambient Air ◽  
Co2 Uptake ◽  
Co2 Removal ◽  
Exhaust Gas ◽  
Technological Parameters ◽  
Efficiency Estimation

Microalgae-mediated CO2 sequestration has been a subject of numerous research works and has become one of the most promising strategies to mitigate carbon dioxide emissions. However, feeding flue and exhaust gas into algae-based systems has been shown to destroy chloroplasts, as well as disrupt photosynthesis and other metabolic processes in microalgae, which directly limits CO2 uptake. CO2 biosequestration in existing photobioreactors (PBRs) is also limited by the low biomass concentration in the growth medium. Therefore, there is a real need to seek alternative solutions that would be competitive in terms of performance and cost-effectiveness. The present paper reports the results of experiments aimed to develop an innovative trickle bed reactor that uses immobilized algae to capture CO2 from flue and exhaust gas (IMC-CO2PBR). In the experiment, ambient air enriched with technical-grade CO2 to a CO2 concentration of 25% v/v was used. The microalgae immobilization technology employed in the experiment produced biomass yields approximating 100 g DM/dm3. A relationship was found between CO2 removal rates and gas volume flux: almost 40% of CO2 was removed at a feed of 25 dm3 of gas per hour, whereas in the 200 dm3/h group, the removal efficiency amounted to 5.9%. The work includes a determination of basic process parameters, presentation of a developed functional model and optimized lighting system, proposals for components to be used in the system, and recommendations for an automation and control system for a full-scale implementation.

scholarly journals Insurance Approval for Definitive Proton Therapy for Prostate Cancer

2021 ◽  
Author(s):  
William M. Mendenhall ◽  
Eric D. Brooks ◽  
Stephanie Smith ◽  
Christopher G. Morris ◽  
Curtis B. Bryant ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Proton Therapy ◽  
Risk Group ◽  
Clinical Factors ◽  
Factors Affecting ◽  
Commercial Insurance ◽  
Insurance Type ◽  
Time Period ◽  
Insured Patients ◽  
Insurance Approval

Abstract Purpose To determine factors that influence insurance approval for definitive proton therapy (PT) for prostate cancer. Materials and Methods Between 2014 and 2018, 1592 insured patients with localized prostate cancer were evaluated and recommended to undergo definitive PT; 547 patients (34.4%) had commercial insurance, whereas 1045 patients (65.6%) had Medicare/Medicaid. Of those with Medicare, 164 patients (15.7%) had Medicare alone; 677 (64.8%) had supplemental plans; and 204 (19.5%) had secondary commercial insurance. Insurance that “covered” PT for prostate cancer implied that it was an indication designated in the coverage policy. “Not covered” means that the insurance policy did not list prostate cancer as an indication for PT. Of all 1592 patients, 1263 (79.3%) belonged to plans that covered PT per policy. However, approval for PT was still required via medical review for 619 patients (38.9%), comparative dosimetry for 56 patients (3.5%), peer-to-peer discussion for 234 patients (14.7%), and administrative law judge hearings for 3 patients (<0.1%). Multivariate analyses of factors affecting approval were conducted, including risk group (low/intermediate versus high), insurance type (commercial versus Medicare/Medicaid), whether PT was included as a covered benefit under the plan (covered versus not covered), and time period (2014-16 versus 2017 versus 2018). Results On multivariate analysis, factors affecting PT approval for prostate treatment included coverage of PT per policy (97.1% had approval with insurance that covered PT versus 48.6% whose insurance did not cover PT; P < .001); insurance type (32.5% had approval with commercial insurance versus 97.4% with Medicare; P < .001); and time, with 877/987 patients (88.9%) approved between 2014 and 2016, 255/312 patients (81.7%) approved during 2017, and 255/293 patients (87.0%) approved thereafter (P = .02). Clinical factors, including risk group, had no bearing on insurance approval (P = .44). Conclusion Proton insurance approval for prostate cancer has decreased, is most influenced by the type of insurance a patient belongs to, and is unrelated to clinical factors (risk group) in this study. More work is needed to help navigate appropriate access to care and to assist patients seeking definitive PT for prostate cancer treatment.

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