Leaf canopy display, stomatal conductance, and photosynthesis in seedlings of three tropical pioneer tree species subjected to drought

1992 ◽  
Vol 70 (12) ◽  
pp. 2334-2338 ◽  
Author(s):  
E. G. Reekie ◽  
P. Wayne
Keyword(s):  
Soil Moisture ◽  
Stomatal Conductance ◽  
Relative Humidity ◽  
Turgor Pressure ◽  
Leaf Size ◽  
Net Photosynthesis ◽  
Fibre Content ◽  
Canopy Architecture ◽  
Species Response ◽  
Cecropia Obtusifolia

Seedlings of Piper aurtitum, Cecropia obtusifolia, and Trichospermum mexicanum, pioneer species of lowland tropical rainforests, were subjected to controlled drought cycles, with stomatal conductance and net photosynthesis monitored to determine species response. The affect of soil moisture on canopy display and the response of stomatal conductance to fluctuations in humidity, light, and temperature were also measured. Stomatal conductance and photosynthesis in Piper and Cecropia showed no relationship with soil moisture until it declined to approximately 20%. At higher soil moistures, stomatal conductance in Piper and Cecropia was positively correlated with relative humidity. In contrast, Trichospermum stomatal conductance and photosynthesis showed no relationship with relative humidity and declined gradually as soil moisture decreased. Canopy display in all three species showed a sharp decline at the end of the drought cycle. There were marked differences among species in canopy structure. Piper and Cecropia both have large leaves and a low fibre content in stems, petioles, and leaves, whereas Trichospermum has much smaller leaves and a higher fibre content. In addition, Piper has a higher leaf to stem ratio than Trichospermum. Differences among species in response of stomatal conductance and photosynthesis to environmental factors may reflect the need to maintain a relatively high turgor pressure in Piper and Cecropia for canopy display. Key words: canopy architecture, drought stress, leaf size, Piper auritum, Cecropia obtusifolia, Trichospermum mexicanum.

Net photosynthesis and stomatal conductance of red spruce twigs before and after twig detachment

1993 ◽  
Vol 23 (4) ◽  
pp. 716-721 ◽  
Author(s):  
Fan-Rui Meng ◽  
Paul A. Arp
Keyword(s):  
Stomatal Conductance ◽  
Relative Humidity ◽  
New Brunswick ◽  
Photosynthetically Active Radiation ◽  
Regression Models ◽  
Net Photosynthesis ◽  
Leaf Temperature ◽  
Red Spruce ◽  
Active Radiation ◽  
Before And After

Rates of net photosynthesis and stomatal conductance of red spruce (Picearubens Sarg.) twigs were measured in field conditions before and after twig detachment on clear midsummer days in New Brunswick. Although these variables did not change significantly within about 6 min after twig detachment, they did drop continually after detachment. Regression models for the rates of net photosynthesis and stomatal conductance were developed that can be used to simulate this drop. Photosynthetically active radiation, leaf temperature, relative humidity, and CO2 concentration were the principal covariates in these models. The regressions improved by including simulated leaf moisture values in the analysis of data obtained after twig detachment.

Ozone effects on grafted mature and juvenile red spruce: photosynthesis, stomatal conductance, and chlorophyll concentration

1993 ◽  
Vol 23 (3) ◽  
pp. 450-456 ◽  
Author(s):  
Joanne Rebbeck ◽  
Keith F. Jensen ◽  
Michael S. Greenwood
Keyword(s):  
Stomatal Conductance ◽  
Surface Area ◽  
Chlorophyll A ◽  
Chlorophyll Concentration ◽  
Net Photosynthesis ◽  
Red Spruce ◽  
Total Chlorophyll ◽  
Specific Leaf Weight ◽  
Open Top Chambers ◽  
Species Response

Red spruce (Picearubens Sarg.) was grown as grafted mature and juvenile scions in open-top chambers and exposed to charcoal-filtered air, nonfiltered air, and nonfiltered air with ozone additions of either 75 or 150 ppb above ambient to determine if tissue age affects the species response to oxidant pollution as measured by photosynthesis, stomatal conductance, and chlorophyll concentration. After 18 weeks of exposure to ozone of concentrations as high as 170 ppb (nonfiltered air + 150 ppb ozone) in an 8-h period, net photosynthesis of grafted red spruce was reduced by ozone. Significant reductions were not observed until September 1988. Mature and juvenile scions grown in nonfiltered air + 150 ppb ozone showed 29 and 40% reductions, respectively, in mean seasonal net photosynthesis (mg CO2•g dry wt.−1•h−1) compared with those plants grown in nonfiltered air. Scion age had a significant effect on net photosynthesis and stomatal conductance. Net photosynthesis (mg CO2•g dry wt.−1•h−1) and stomatal conductance were 38 and 47% higher, respectively, in juvenile than in mature scions. Chlorophyll a and total chlorophyll concentration of juvenile scion needles were significantly reduced 19 and 24%, respectively, when grown in nonfiltered air + 150 ppb ozone compared with that grown in charcoal-filtered air (p < 0.01). Mature scions had significantly more chlorophyll a than juvenile scions in October 1988. Current-year needles collected from mature scions had significantly greater mass, length, one-sided projected surface area, width, and thickness than juvenile scions. Mature scions had significantly lower needle numbers per centimetre branch than did juvenile scions. No differences in specific leaf weight were observed. Mature scions had less ozone uptake than did juvenile scions.

scholarly journals Effects of Soil Moisture, Cultivar, and Postharvest Handling on Pillowy Fruit Disorder in Cucumber

1994 ◽  
Vol 119 (6) ◽  
pp. 1234-1242 ◽  
Author(s):  
John P. Navazio ◽  
Jack E. Staub
Keyword(s):  
Soil Moisture ◽  
Stomatal Conductance ◽  
Relative Humidity ◽  
Environmental Conditions ◽  
Dry Weight ◽  
Moisture Stress ◽  
Normal Leaf ◽  
High Soil Moisture ◽  
Postharvest Handling ◽  
And Storage

Two experiments (1989 and 1990) were designed to characterize the response of cucumber (Cucumis sativus L.) plants with different leaf types [normal leaf (LL) vs. little leaf (ll)] to high soil moisture tension (SMT) and to determine whether hydrocooling would reduce the severity of pillowy fruit disorder (PFD). Comparisons were made among nine cultivars (7 LL and 2 ll) for aboveground vegetative and fruit response, and between two irrigation regimes. High SMT generally caused increased wilt ratings and stomatal conductance and decreased plant dry weight. PFD severity of fruit from watered plots was less [61% (Expt. 1, 1989) and 26% (Expt. 1, 1990)] than of fruit harvested from plots in which water was withheld. The response of the two ll cultivars to moisture stress differed depending on environmental conditions. Increased PFD severity was associated with increased temperature, lower relative humidity (RH), and excluding hydrocooling during postharvest handling. Of the four storage treatments examined, hydrocooling to ≈8.5C then storage at 15C and 85% RH for 4 days produced fruit with the least PFD symptoms. Fruit of `Carolina' (LL) exhibited the highest PFD ratings, while those of `Calypso' (LL) were consistently low compared to other cultivars. Processors can lower PFD incidence and severity by ensuring that adequate moisture is available to plants during fruit enlargement and that harvested fruit are hydrocooled before shipping and storage.

scholarly journals A Calibrated Time Domain Transmissometry Soil Moisture Sensor Can Be Used for Precise Automated Irrigation of Container-grown Plants

HortScience ◽  
2011 ◽  
Vol 46 (6) ◽  
pp. 889-894 ◽  
Author(s):  
Julián Miralles-Crespo ◽  
Marc W. van Iersel
Keyword(s):  
Soil Moisture ◽  
Time Domain ◽  
Crop Production ◽  
Irrigation System ◽  
Leaf Size ◽  
Net Photosynthesis ◽  
Sensor Calibration ◽  
Production Cycle ◽  
Moisture Sensor ◽  
Soilless Substrate

Irrigation control systems that irrigate container-grown plants based on crop water needs can reduce water and fertilizer use and increase the sustainability of ornamental crop production. The use of soil moisture sensors to determine when to irrigate is a viable option. We tested a commercially available irrigation controller (CS3500; Acclima, Meridian, ID), which uses time domain transmissometry (TDT) sensors to measure soil volumetric water content (θ). The objectives of this study were: 1) to test the accuracy of TDT sensors in soilless substrate; 2) to quantify the ability of the Acclima CS3500 irrigation controller to maintain stable θ readings during the production of container-grown begonia (Begonia semperflorens L.) by turning a drip irrigation system on and off as needed; and 3) to study the growth and photosynthetic physiology of begonia at six θ levels. Calibration of the TDT sensors in pots filled with substrate (but without plants) showed that the θ determined by the TDT sensors had a very close relationship (R2 = 0.99) with the gravimetrically determined θ, but the TDT sensors underestimated θ by ≈0.08 m3·m−3. Therefore, a custom calibration of the TDT sensors for the soilless substrate was necessary to get accurate θ data. The irrigation controller was programmed to maintain six θ thresholds, ranging from 0.136 to 0.472 m3·m−3 (based on our own sensor calibration), and was able to maintain θ readings within 0.008 m3·m−3 of the threshold. Theta and Sigma probes were used to collect comparative θ and bulk electrical conductivity (EC) data, respectively. The results showed a strong correlation with TDT sensor measurements of θ (R2 = 0.92) but a moderate relationship for bulk EC (R2 = 0.53). The begonias had similar dry weight at θ levels of 0.348 m3·m−3 and higher, whereas total evapotranspiration increased linearly with the θ threshold. The lowest θ threshold reduced leaf size, net photosynthesis (Pn), and stomatal conductance (gS). Overall, the TDT sensors can provide accurate measurements of θ in soilless substrate but need substrate-specific calibration. The Acclima CS3500 controller, using TDT sensors, was able to maintain stable θ readings throughout a production cycle. These results suggest that this irrigation controller may be suitable for production of greenhouse crops as well as in drought stress research.

scholarly journals Spatiotemporal Variation of the Burned Area and Its Relationship with Climatic Factors in Central Kazakhstan

2021 ◽  
Vol 13 (2) ◽  
pp. 313
Author(s):  
Yongfang Xu ◽  
Zhaohui Lin ◽  
Chenglai Wu
Keyword(s):  
Soil Moisture ◽  
Relative Humidity ◽  
Central Asia ◽  
Climatic Factors ◽  
Spatiotemporal Variation ◽  
Lower Atmosphere ◽  
Burned Area ◽  
Circulation Index ◽  
Precipitation Anomalies ◽  
The Relationship

Central Asia is prone to wildfires, but the relationship between wildfires and climatic factors in this area is still not clear. In this study, the spatiotemporal variation in wildfire activities across Central Asia during 1997–2016 in terms of the burned area (BA) was investigated with Global Fire Emission Database version 4s (GFED4s). The relationship between BA and climatic factors in the region was also analyzed. The results reveal that more than 90% of the BA across Central Asia is located in Kazakhstan. The peak BA occurs from June to September, and remarkable interannual variation in wildfire activities occurs in western central Kazakhstan (WCKZ). At the interannual scale, the BA is negatively correlated with precipitation (correlation coefficient r = −0.66), soil moisture (r = −0.68), and relative humidity (r = −0.65), while it is positively correlated with the frequency of hot days (r = 0.37) during the burning season (from June to September). Composite analysis suggests that the years in which the BA is higher are generally associated with positive geopotential height anomalies at 500 hPa over the WCKZ region, which lead to the strengthening of the downdraft at 500 hPa and the weakening of westerlies at 850 hPa over the region. The weakened westerlies suppress the transport of water vapor from the Atlantic Ocean to the WCKZ region, resulting in decreased precipitation, soil moisture, and relative humidity in the lower atmosphere over the WCKZ region; these conditions promote an increase in BA throughout the region. Moreover, the westerly circulation index is positively correlated (r = 0.53) with precipitation anomalies and negatively correlated (r = −0.37) with BA anomalies in the WCKZ region during the burning season, which further underscores that wildfires associated with atmospheric circulation systems are becoming an increasingly important component of the relationship between climate and wildfire.

scholarly journals Sensitivity of stomatal conductance to soil moisture: implications for tropospheric ozone

2017 ◽  
Author(s):  
Alessandro Anav ◽  
Chiara Proietti ◽  
Laurent Menut ◽  
Stefano Carnicelli ◽  
Alessandra De Marco ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Stomatal Conductance ◽  
Soil Water ◽  
Water Uptake ◽  
Atmospheric Chemistry ◽  
Water Availability ◽  
Dry Deposition ◽  
Lower Troposphere ◽  
Lower Atmosphere ◽  
Water Limitation

Abstract. Soil moisture and water stress play a pivotal role in regulating stomatal behaviour of plants; however, in the last decade, the role of water availability was often neglected in atmospheric chemistry modelling studies as well as in integrated risk assessments, despite through stomata plants remove a large amount of atmospheric compounds from the lower troposphere. The main aim of this study is to evaluate the effect of soil water limitation on stomatal conductance and assess the resulting changes in atmospheric chemistry testing various hypotheses of water uptake by plants in the rooting zone; following the main assumption that roots maximize water uptake, i.e. they adsorb water at different soil depths depending on the water availability, we improve the dry deposition scheme within the chemistry transport model CHIMERE. Results highlight how dry deposition significantly declines when soil moisture is used to regulate the stomatal opening, mainly in the semi-arid environments: in particular, over Europe the amount of ozone removed by dry deposition in one year without considering any soil water limitation to stomatal conductance is about 8.5 Tg O3, while using a dynamic layer that ensures plants to maximize the water uptake from soil, we found a reduction of about 10 % in the amount of ozone removed by dry deposition (~ 7.7 Tg O3). Despite dry deposition occurs from top of canopy to ground level, it affects the concentration of gases remaining into the lower atmosphere with a significant impact on ozone concentration (up to 4 ppb) extending from the surface to the upper troposphere (up to 650 hPa). Our results shed light on the importance of improving the parameterizations of processes occurring at plant level (i.e. from the soil to the canopy) as they have significant implications on concentration of gases in the lower troposphere.

scholarly journals Using Plant Temperature to Evaluate the Response of Stomatal Conductance to Soil Moisture Deficit

Forests ◽  
2015 ◽  
Vol 6 (12) ◽  
pp. 3748-3762 ◽  
Author(s):  
Ming-Han Yu ◽  
Guo-Dong Ding ◽  
Guang-Lei Gao ◽  
Yuan-Yuan Zhao ◽  
Lei Yan ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Stomatal Conductance ◽  
Soil Moisture Deficit ◽  
Moisture Deficit

scholarly journals Growth and physiological response of two biomass sorghum (Sorghum bicolor (L.) Moench) genotypes bred for different environments, to contrasting levels of soil moisture

2015 ◽  
Vol 10 (4) ◽  
pp. 208 ◽  
Author(s):  
Lorenzo Barbanti ◽  
Ahmad Sher ◽  
Giuseppe Di Girolamo ◽  
Elio Cirillo ◽  
Muhammad Ansar
Keyword(s):  
Soil Moisture ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Water Content ◽  
Aboveground Biomass ◽  
Relative Water Content ◽  
Physiological Response ◽  
Field Capacity ◽  
Biomass Sorghum ◽  
Relative Water

A better understanding of plant mechanisms in response to drought is a strong premise to achieving high yields while saving unnecessary water. This is especially true in the case of biomass crops for non-food uses (energy, fibre and forage), grown with limited water supply. In this frame, we investigated growth and physiological response of two genotypes of biomass sorghum (<em>Sorghum bicolor</em> (L.) Moench) to contrasting levels of soil moisture in a pot experiment carried out in a greenhouse. Two water regimes (high and low water, corresponding to 70% and 30% field capacity) were applied to JS-2002 and Trudan-8 sorghum genotypes, respectively bred for dry sub-tropical and mild temperate conditions. Two harvests were carried out at 73 and 105 days after seeding. Physiological traits (transpiration, photosynthesis and stomatal conductance) were assessed in four dates during growth. Leaf water potential, its components and relative water content were determined at the two harvests. Low watering curbed plant height and aboveground biomass to a similar extent (ca. 􀀀70%) in both genotypes. JS-2002 exhibited a higher proportion of belowground to aboveground biomass, <em>i.e</em>., a morphology better suited to withstand drought. Despite this, JS-2002 was more affected by low water in terms of physiology: during the growing season, the average ratio in transpiration, photosynthesis and stomatal conductance between droughty and well watered plants was, respectively, 0.82, 0.80 and 0.79 in JS-2002; 1.05, 1.08 and 1.03 in Trudan-8. Hence Trudan-8 evidenced a ca. 20% advantage in the three traits. In addition, Trudan-8 could better exploit abundant moisture (70% field capacity), increasing aboveground biomass and water use efficiency. In both genotypes, drought led to very low levels of leaf water potential and relative water content, still supporting photosynthesis. Hence, both morphological and physiological characteristics of sorghum were involved in plant adaptation to drought, in accordance with previous results. Conversely, the common assumption that genotypes best performing under wet conditions are less suited to face drought was contradicted by the results of the two genotypes in our experiment. This discloses a potential to be further exploited in programmes of biomass utilization for various end uses, although further evidence at greenhouse and field level is needed to corroborate this finding.

scholarly journals Physiological responses of beet plants irrigated with saline water and silicon application

2020 ◽  
Vol 11 ◽  
pp. E3113
Author(s):  
José Sebastião de Melo Filho ◽  
Toshik Iarley da Silva ◽  
Anderson Carlos de Melo Gonçalves ◽  
Leonardo Vieira de Sousa ◽  
Mario Leno Martins Véras ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Carbon Concentration ◽  
Saline Water ◽  
Block Design ◽  
Essential Element ◽  
Net Photosynthesis ◽  
Crop Productivity ◽  
Experimental Unit ◽  
Randomized Block Design

Although not considered an essential element, silicon can be used to increase crop productivity, especially under stress conditions. In this sense, the objective was to evaluate the gas exchange of beet plants irrigated with saline water depending on the application of silicon. The experiment was conducted in a randomized block design, in a 5 x 5 factorial, referring to five levels of electrical conductivity of irrigation water (ECw): (0.5; 1.3; 3.25; 5.2 and 6.0 dS m-1) and five doses of silicon (0.00; 2.64; 9.08; 15.52 and 18.16 mL L-1), with six beet plants as an experimental unit. The effect of treatments on beet culture was evaluated at 30 and 60 days after irrigation with saline water from measurements of internal carbon concentration, stomatal conductance, net photosynthesis rate, instantaneous water use efficiency and instantaneous carboxylation efficiency using the LCpro+Sistem infrared gas analyzer (IRGA). Irrigation with saline water reduced the gas exchange of beet plants at 60 days after irrigation, but at 30 days after irrigation, the use of saline water increased stomatal conductance, transpiration rate and internal carbon concentration. The application of silicon decreased stomatal conductance, internal carbon concentration and efficiency in the use of water, but increased the rate of net photosynthesis, the rate of transpiration and instantaneous efficiency of carboxylation at 30 and 60 days after irrigation.

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