scholarly journals Robust estimates of cuticle conductance on stomatous leaf surfaces during the light induction of photosynthesis

2020 ◽  
Author(s):  
Jun Tominaga ◽  
Joseph R. Stinziano ◽  
David T. Hanson
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
List Type ◽  
Light Induction ◽  
Tobacco Leaves ◽  
Robust Estimates ◽  
Leaf Surfaces ◽  
The Difference ◽  
Source Of Error ◽  
Standard Gas

SummaryCuticle conductance (gcw) can bias calculations of intercellular CO2 concentration inside the leaf (Ci) when stomatal conductance (gsw) is small.We examined how the light induction of photosynthesis impacts calculations by directly measuring Ci along with standard gas exchange in sunflower and tobacco leaves.When photosynthesis was induced from dark to saturating light (1200 μmol m−2 s−1 PAR) the calculated Ci was significantly larger than measured Ci and the difference decreased as gsw increased. This difference could lead to over-estimation of rubisco deactivation by limited CO2 supply during early induction of photosynthesis. However, only small differences in Ci were observed during the induction from shade (50 μmol m−2 s−1 PAR) because gsw was sufficiently large. The induction from dark also allowed robust estimations of gcw when combined with direct Ci measurements. These gcw estimates succeeded in correcting the calculation, suggesting that the cuticle was the major source of error.Despite a technical restriction to amphi-stomatous leaves, the presented technique has a potential to provide insights into the cuticle conductance on intact stomatous leaf surfaces.

scholarly journals Minimum conductance in leaves—cuticle, leaky stomata, or water vapor saturation?

2020 ◽  
Author(s):  
Jun Tominaga ◽  
Joseph R. Stinziano ◽  
David T. Hanson
Keyword(s):  
Water Vapor ◽  
Gas Exchange ◽  
Water Status ◽  
Severe Drought ◽  
List Type ◽  
Leaf Water Status ◽  
Direct Measurements ◽  
Detached Leaves ◽  
The Difference ◽  
Gas Exchange Model

SummaryMinimum conductance (gw,min) in leaves is important for water relations in land plants. Yet, its regulation is unclear due to measurement constraints.Cuticle conductance to water vapor (gcw) was estimated from the difference between calculated and direct measurement of CO2 concentration in the leaf airspace (Ci) of amphi-stomatous tobacco and sunflower. We estimated gcw in a series of light and dark experiments, and partitioned gw,min into cuticle and stomatal components. Some leaves were detached to simulate severe drought through desiccation conditions where gw,min is generally determined.Between light and dark experiments each gcw was in close agreement, and successfully corrected the discrepancies of calculations from direct measurements. In the dark, either stomatal or cuticle conductance dominated the gw,min, suggesting either of them can control the minimum water loss. In the detached leaves, gcw could not be estimated likely due to unsaturation in the leaf airspace, and gw,min was progressively underestimated.Besides cuticle, leaf water status is a potential pitfall of the standard gas exchange model. Our technique is useful to study the minimal gas exchange as well as to refine the model.

scholarly journals Robust estimates of cuticular conductance to water on a stomatous leaf surface

2021 ◽  
Author(s):  
Jun Tominaga ◽  
Joseph Stinziano ◽  
David T. Hanson
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Simple Technique ◽  
Leaf Surface ◽  
Leaf Gas Exchange ◽  
Stomatal Closure ◽  
Rapid Screening ◽  
Induction Phase ◽  
Robust Estimates ◽  
Co Concentration

In leaf gas exchange measurements, cuticular conductance to water (g) is indistinguishable from and included in stomatal conductance to water vapor (g). Here we developed a simple technique to isolate g by directly measuring leaf intercellular CO concentration (C) along with gas exchange during photosynthetic light induction. We derived stomatal conductance to CO (g) from the C independently of g. Plotting g against g during the early induction phase within ~10 min, we found a highly linear relationship with a positive intercept. Assuming negligible cuticular CO transport, complete stomatal closure occurs when g=0. Then, we considered the residual g (i.e., intercept) as g. Indeed, these g estimates succeeded in correcting the calculation. Our technique, owing to its robustness and increased throughput, will allow for more rapid screening of crops, more reliable gas exchange analysis, and more accurate prediction of plant function under natural environmental conditions.

Effect of Mycorrhizal Fungi on Gas Exchange of Micropropagated Guava Plantlets (Psidium guajava L.) during Acclimatization and Plant Establishment

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 501c-501
Author(s):  
Andrés A. Estrada-Luna ◽  
Jonathan N. Egilla ◽  
Fred T. Davies
Keyword(s):  
Tissue Culture ◽  
Stomatal Conductance ◽  
Gas Exchange ◽  
Vapor Pressure ◽  
Mycorrhizal Fungi ◽  
Vapor Pressure Deficit ◽  
Psidium Guajava ◽  
Glomus Etunicatum ◽  
Plant Establishment ◽  
Use Efficiency

The effect of mycorrhizal fungi on gas exchange of micropropagated guava plantlets (Psidium guajava L.) during acclimatization and plant establishment was determined. Guava plantlets (Psidium guajava L. cv. `Media China') were asexually propagated through tissue culture and acclimatized in a glasshouse for eighteen weeks. Half of the plantlets were inoculated with ZAC-19, which is a mixed isolate containing Glomus etunicatum and an unknown Glomus spp. Plantlets were fertilized with modified Long Ashton nutrient solution containing 11 (g P/ml. Gas exchange measurements included photosynthetic rate (A), stomatal conductance (gs), internal CO2 concentration (Ci), transpiration rate (E), water use efficiency (WUE), and vapor pressure deficit (VPD). Measurements were taken at 2, 4, 8 and 18 weeks after inoculation using a LI-6200 portable photosynthesis system (LI-COR Inc. Lincoln, Neb., USA). Two weeks after inoculation, noninoculated plantlets had greater A compared to mycorrhizal plantlets. However, 4 and 8 weeks after inoculation, mycorrhizal plantlets had greater A, gs, Ci and WUE. At the end of the experiment gas exchange was comparable between noninoculated and mycorrhizal plantlets.

The Effects of Drought on Leaf Gas Exchange and Growth of Three Species of Herbaceous Perennials

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 540a-540
Author(s):  
K.J. Prevete ◽  
R.T. Fernandez
Keyword(s):  
Drought Stress ◽  
Stomatal Conductance ◽  
Gas Exchange ◽  
Drought Tolerance ◽  
Transpiration Rate ◽  
Leaf Gas Exchange ◽  
Gas Analysis ◽  
Herbaceous Perennials ◽  
Effects Of Drought ◽  
Analysis System

Three species of herbaceous perennials were tested on their ability to withstand and recover from drought stress periods of 2, 4, and 6 days. Eupatorium rugosum and Boltonia asteroides `Snowbank' were chosen because of their reported drought intolerance, while Rudbeckia triloba was chosen based on its reported drought tolerance. Drought stress began on 19 Sept. 1997. Plants were transplanted into the field the day following the end of each stress period. The effects of drought on transpiration rate, stomatal conductance, and net photosynthetic rate were measured during the stress and throughout recovery using an infrared gas analysis system. Leaf gas exchange measurements were taken through recovery until there were no differences between the stressed plants and the control plants. Transpiration, stomatal conductance, and photosynthesis of Rudbeckia and Boltonia were not affected until 4 days after the start of stress. Transpiration of Eupatorium decreased after 3 days of stress. After rewatering, leaf gas exchange of Boltonia and Rudbeckia returned to non-stressed levels quicker than Eupatorium. Growth measurements were taken every other day during stress, and then weekly following transplanting. Measurements were taken until a killing frost that occurred on 3 Nov. There were no differences in the growth between the stressed and non-stressed plants in any of the species. Plants will be monitored throughout the winter, spring, and summer to determine the effects of drought on overwintering capability and regrowth.

scholarly journals Normal Cyclic Variation in CO2 Concentration in Indoor Chambers Decreases Leaf Gas Exchange and Plant Growth

Plants ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 663
Author(s):  
James Bunce
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Leaf Gas Exchange ◽  
Genetic Material ◽  
Co2 Concentration ◽  
Cyclic Variation ◽  
Indoor Exposure ◽  
Elevated Atmospheric Co2 ◽  
Gas Exchange System ◽  
Opening And Closing

Attempts to identify crop genetic material with larger growth stimulation at projected elevated atmospheric CO2 concentrations are becoming more common. The probability of reductions in photosynthesis and yield caused by short-term variation in CO2 concentration within elevated CO2 treatments in the free-air CO2 enrichment plots raises the question of whether similar effects occur in glasshouse or indoor chamber experiments. These experiments were designed to test whether even the normal, modest, cyclic variation in CO2 concentration typical of indoor exposure systems have persistent impacts on photosynthesis and growth, and to explore mechanisms underlying the responses observed. Wheat, cotton, soybeans, and rice were grown from seed in indoor chambers at a mean CO2 concentration of 560 μmol mol−1, with “triangular” cyclic variation with standard deviations of either 4.5 or 18.0 μmol mol−1 measured with 0.1 s sampling periods with an open path analyzer. Photosynthesis, stomatal conductance, and above ground biomass at 20 to 23 days were reduced in all four species by the larger variation in CO2 concentration. Tests of rates of stomatal opening and closing with step changes in light and CO2, and tests of responses to square-wave cycling of CO2 were also conducted on individual leaves of these and three other species, using a leaf gas exchange system. Reduced stomatal conductance due to larger amplitude cycling of CO2 during growth occurred even in soybeans and rice, which had equal rates of opening and closing in response to step changes in CO2. The gas exchange results further indicated that reduced mean stomatal conductance was not the only cause of reduced photosynthesis in variable CO2 conditions.

Tobacco Leaf Grading Based on Deep Convolutional Neural Networks and Machine Vision

2021 ◽  
Vol 65 (1) ◽  
pp. 11-22
Author(s):  
Mengyao Lu ◽  
Shuwen Jiang ◽  
Cong Wang ◽  
Dong Chen ◽  
Tian’en Chen
Keyword(s):  
Neural Networks ◽  
Deep Learning ◽  
Transfer Learning ◽  
Convolutional Neural Networks ◽  
Classification Accuracy ◽  
Classification Model ◽  
List Type ◽  
Tobacco Leaves ◽  
Tobacco Leaf ◽  
Grading Model

HighlightsA classification model for the front and back sides of tobacco leaves was developed for application in industry.A tobacco leaf grading method that combines a CNN with double-branch integration was proposed.The A-ResNet network was proposed and compared with other classic CNN networks.The grading accuracy of eight different grades was 91.30% and the testing time was 82.180 ms, showing a relatively high classification accuracy and efficiency.Abstract. Flue-cured tobacco leaf grading is a key step in the production and processing of Chinese-style cigarette raw materials, directly affecting cigarette blend and quality stability. At present, manual grading of tobacco leaves is dominant in China, resulting in unsatisfactory grading quality and consuming considerable material and financial resources. In this study, for fast, accurate, and non-destructive tobacco leaf grading, 2,791 flue-cured tobacco leaves of eight different grades in south Anhui Province, China, were chosen as the study sample, and a tobacco leaf grading method that combines convolutional neural networks and double-branch integration was proposed. First, a classification model for the front and back sides of tobacco leaves was trained by transfer learning. Second, two processing methods (equal-scaled resizing and cropping) were used to obtain global images and local patches from the front sides of tobacco leaves. A global image-based tobacco leaf grading model was then developed using the proposed A-ResNet-65 network, and a local patch-based tobacco leaf grading model was developed using the ResNet-34 network. These two networks were compared with classic deep learning networks, such as VGGNet, GoogLeNet-V3, and ResNet. Finally, the grading results of the two grading models were integrated to realize tobacco leaf grading. The tobacco leaf classification accuracy of the final model, for eight different grades, was 91.30%, and grading of a single tobacco leaf required 82.180 ms. The proposed method achieved a relatively high grading accuracy and efficiency. It provides a method for industrial implementation of the tobacco leaf grading and offers a new approach for the quality grading of other agricultural products. Keywords: Convolutional neural network, Deep learning, Image classification, Transfer learning, Tobacco leaf grading

Gas exchange in dogs in the prone and supine positions

1992 ◽  
Vol 72 (6) ◽  
pp. 2292-2297 ◽  
Author(s):  
K. C. Beck ◽  
J. Vettermann ◽  
K. Rehder
Keyword(s):  
Blood Flow ◽  
Gas Exchange ◽  
Prone Position ◽  
Pulmonary Blood Flow ◽  
Random Order ◽  
Arterial Pco2 ◽  
Supine Posture ◽  
Pulmonary Shunting ◽  
The Difference ◽  
Arterial Po2

To determine the cause of the difference in gas exchange between the prone and supine postures in dogs, gas exchange was assessed by the multiple inert gas elimination technique (MIGET) and distribution of pulmonary blood flow was determined using radioactively labeled microspheres in seven anesthetized paralyzed dogs. Each animal was studied in the prone and supine positions in random order while tidal volume and respiratory frequency were kept constant with mechanical ventilation. Mean arterial PO2 was significantly lower (P less than 0.01) in the supine [96 +/- 10 (SD) Torr] than in the prone (107 +/- 6 Torr) position, whereas arterial PCO2 was constant (38 Torr). The distribution of blood flow (Q) vs. ventilation-to-perfusion ratio obtained from MIGET was significantly wider (P less than 0.01) in the supine [ln SD(Q) = 0.75 +/- 0.26] than in the prone position [ln SD (Q) = 0.34 +/- 0.05]. Right-to-left pulmonary shunting was not significantly altered. The distribution of microspheres was more heterogeneous in the supine than in the prone position. The larger heterogeneity was due in part to dorsal-to-ventral gradients in Q in the supine position that were not present in the prone position (P less than 0.01). The decreased efficiency of oxygenation in the supine posture is caused by an increased ventilation-to-perfusion mismatch that accompanies an increase in the heterogeneity of Q distribution.

Evaluation of two alternative ablation treatments for cervical pre-cancer against standard gas-based cryotherapy: a randomized non-inferiority study

2019 ◽  
Vol 29 (5) ◽  
pp. 851-856 ◽  
Author(s):  
Miriam Cremer ◽  
Karla Alfaro ◽  
Jillian Garai ◽  
Manuel Salinas ◽  
Mauricio Maza ◽  
...  
Keyword(s):  
Low Income ◽  
Histological Evaluation ◽  
Cervical Tissue ◽  
Post Surgery ◽  
Pain Scores ◽  
Patient Pain ◽  
The Difference ◽  
Cure Rates ◽  
Treatment Application ◽  
Standard Gas

IntroductionGas-based cryotherapy is the conventional ablative treatment for cervical pre-cancer in low-income settings, but the use of gas poses significant challenges. We compared the depth of necrosis induced by gas-based cryotherapy with two gas-free alternatives: cryotherapy using CryoPen,and thermoablation.MethodsWe conducted a five-arm randomized non-inferiority trial: double-freeze carbon dioxide (CO2) cryotherapy (referent), single-freeze CO2 cryotherapy, double-freeze CryoPen, single-freeze CryoPen, and thermoablation. Subjects were 130 women scheduled for hysterectomy for indications other than cervical pathology, and thus with healthy cervical tissue available for histological evaluation of depth of necrosis post-surgery. The null hypothesis was rejected (ie, conclude non-inferiority) if the upper bound of the 90% confidence interval (90% CI) for the difference in mean depth of necrosis (referent minus each experimental method) was <1.14 mm. Patient pain during treatment was reported on a scale of 0 (no pain) to 10 (worst pain).ResultsA total of 133 patients were enrolled in the study. The slides from three women were deemed unreadable. One patient was excluded because her hysterectomy was postponed for reasons unrelated to the study, and two patients were excluded because treatment application did not follow the established protocol. For the remaining 127 women, mean depth of necrosis for double-freeze CO2 (referent) was 6.0±1.6 mm. Differences between this and other methods were: single-freeze CO2 = 0.4 mm (90% CI −0.4 to 1.2 mm), double-freeze CryoPen= 0.7 mm (90% CI 0.04 to 1.4 mm), single-freeze CryoPen= 0.5 mm (90% CI −0.2 to 1.2 mm), and thermoablation = 2.6 mm (90% CI 2.0 to 3.1 mm). Mean pain levels were 2.2±1.0 (double-freeze CO2 cryotherapy), 1.8±0.8 (single-freeze CO2 cryotherapy), 2.5±1.4 (double-freeze CryoPen), 2.6±1.4 (single-freeze CryoPen), and 4.1±2.3 (thermoablation).DiscussionCompared with the referent, non-inferiority could not be concluded for other methods. Mean pain scores were low for all treatments. Depth of necrosis is a surrogate for treatment efficacy, but a randomized clinical trial is necessary to establish true cure rates.

Boron Supply and Water Deficit Consequences in Young Paricá (Schizolobium parahyba var. amazonicum) Plants

2016 ◽  
Vol 44 (1) ◽  
pp. 250-256 ◽  
Author(s):  
Bianca do Carmo SILVA ◽  
Pêola Reis de SOUZA ◽  
Daihany Moraes CALLEGARI ◽  
Vanessa Ferreira ALVES ◽  
Allan Klynger da Silva LOBATO ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Stomatal Conductance ◽  
Gas Exchange ◽  
Water Use Efficiency ◽  
Water Deficit ◽  
Water Use ◽  
Electrolyte Leakage ◽  
Tolerance Mechanism ◽  
Schizolobium Parahyba ◽  
Use Efficiency

Boron (B) is a very important nutrient required by forest plants; when supplied in adequate amounts, plants can ameliorate the negative effects of abiotic stresses. The objective of this study was to (i) investigate gas exchange, (ii) measure oxidant and antioxidant compounds, and (iii) respond how B supply acts on tolerance mechanism to water deficit in young Schizolobium parahyba plants. The experiment employed a factorial that was entirely randomised, with two boron levels (25 and 250 µmol L-1, simulating conditions of sufficient B and high B, respectively) and two water conditions (control and water deficit). Water deficit induced negative modifications on net photosynthetic rate, stomatal conductance and water use efficiency, while B high promoted intensification of the effects on stomatal conductance and water use efficiency. Hydrogen peroxide and electrolyte leakage of both tissues suffered non-significant increases after B high and when applied water deficit. Ascorbate levels presented increases after water deficit and B high to leaf and root. Our results suggested that the tolerance mechanism to water deficit in young Schizolobium parahyba plants is coupled to increases in total glutathione and ascorbate aiming to control the overproduction of hydrogen peroxide and alleviates the negative consequences on electrolyte leakage and gas exchange. In relation to B supply, this study proved that sufficient level promoted better responses under control and water deficit conditions.

scholarly journals Physiological Effects of Exercising at Different Intensities Wearing TNT or Double-layer Cotton Facemasks Compared to Not Wearing a Mask

2020 ◽  
Author(s):  
Fabrício Braga ◽  
Gabriel Espinosa ◽  
Amanda Monteiro ◽  
Beatriz Marinho ◽  
Eduardo Drummond
Keyword(s):  
Gas Exchange ◽  
Double Layer ◽  
Breathing Pattern ◽  
Pulmonary Ventilation ◽  
Effect Sizes ◽  
Moderate Intensity ◽  
List Type ◽  
Physiological Effects ◽  
Physiological Dead Space ◽  
End Tidal

Abstract We compared the physiological differences between exercising wearing a TNT or a double-layer-cotton (DLC) facemask (FM) and not wearing a mask (NM). Sixteen volunteers underwent 4 sets (S) of 2 sequential bouts (B). B1 and B2 corresponded to light and moderate intensity cycling, respectively. FMs were used as follows: S1: NM; S2: TNT or DLC; S3: DLC or TNT; and S4: NM. Metabolic, pulmonary, and perceptual variables were collected. The main results are expressed as effect sizes and confidence intervals (ES [95%CI]) for TNT and DLC unless otherwise indicated. Compared to NM, FM increased the duty cycle (B1=1.11[0.58-1.61] and 1.53[0.81-2.18]; B2=1.27[0.63-1.84] and 1.93[0.97-2.68]) and decreased breath frequency (B1=0.59[0.23-0.94] and 1.43[0.79-2.07], B2=0.39[0.05-0.71] and 1.33[0.71-1.94]). Only B1 tidal volume increased (0.33[0.09-0.56] and 0.62[0.18-1.05]) enough to avoid a ventilation reduction with TNT but not with DLC (B1=0.52[0.23-0.79]; B2=0.84[0.44-1.22]). Both FMs reduced oxygen saturation in B1 (0.56 [0.07-1.03] and 0.69 [0.09-1.28]) but only DLC did so in B2 (0.66 [0.11-1.13]). Both end tidal CO2 (B1=0.23[0.05-0.4] and 0.71[0.38-1.02]; B2=0.56[0.2-0.9] and 1.20[0.65-1.68]) and mixed-expired-CO2 (B1=0.74[0.38-1.08] 1.71[1.03-2.37], B2=0.94[0.45-1.38] and 1.78[0.97-2.42]) increased with FMs. Ventilatory adaptations imposed during FM exercising influenced blood-lung gas exchange. Larger ESs were seen with DLC. No adverse changes to human health were observed. Novelty Bullets Facemasks affect the breathing pattern by changing the frequency and amplitude of pulmonary ventilation. The augmented ventilatory work increases VO2, VCO2, and RPE and promotes non-concerning drops in SpO2 and CO2 retention. Increased inspiratory and expiratory pressure can account for the reduction in pulmonary physiological dead space.

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