scholarly journals Ecophysiology ofpotentilla gracilisdouglas ex hook (rosaceae): effects of night temperature and water stress on photosynthetic gas exchange

2019 ◽  
Author(s):  
Madhav P. Nepal ◽  
Virginia S. Berg
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Gas Exchange ◽  
Light Intensity ◽  
Light Response ◽  
Growing Season ◽  
Night Temperature ◽  
Response Curves ◽  
Photosynthetic Gas Exchange ◽  
Light Response Curves

ABSTRACTPlants in stressful environments have evolved strategies to cope with fluctuating environmental conditions.Potentilla gracilis, also known as Alpine Cinquefoil, grows in alpine meadows of the Rocky Mountains (USA), and is subjected to wide ranges of temperature, light intensity and water availability on a time scale of minutes to days during the growing season. Leaves often freeze to a brittle state at night, are exposed to high radiation while still frosty, dehydrate to wilting during the following light period, and then repeat the cycle the following day. The main objective of this research was to determine the effect of night temperature on subsequent photosynthetic gas exchange inP. gracilis. We used a photosynthetic gas exchange system to compare assimilation and stomatal conductance from light response curves of cold-acclimatedP. gracilisfollowing warm and chilling nights, and for plants at different water potentials. From the light response curves, dark respiration, light compensation point, maximum assimilation, light saturation point, and inhibition of photosynthesis were determined and were compared among the same plants under varying conditions. Assimilation and stomatal conductance decreased with the fall in measurement temperature, following chilling nights, and with the severity of water stress. Low night temperature and high photon flux density during the daytime, which are very common during the growing season in the field, cause a reduction in photosynthesis of the plant. The probable underlying damage during inhibition is likely repairable indicating protection rather than damage. The cold nocturnal temperature, with its less efficient biochemical repair capabilities, may partly be responsible for the reduction in assimilation of the following day.P. gracilisspecies exhibited persistent acquired freezing tolerance; substantial photosynthetic productivity over a wide range of light intensity and temperature; and significant tolerance of, and rapid recovery from, severe drought; making a maximum use of often challenging resources.

Light response of photosynthesis and stomatal conductance of rose leaves in the canopy profile: the effect of lighting on the adaxial and the abaxial sides

2020 ◽  
Vol 47 (7) ◽  
pp. 639
Author(s):  
Roberta Paradiso ◽  
Pieter H. B. de Visser ◽  
Carmen Arena ◽  
Leo F. M. Marcelis
Keyword(s):  
Stomatal Conductance ◽  
Light Transmission ◽  
Model Simulation ◽  
Light Response ◽  
Substantial Part ◽  
Response Curves ◽  
Abaxial Side ◽  
Area Index ◽  
Light Response Curves ◽  
Light Absorbance

We investigated the light response of leaf photosynthesis, stomatal conductance and optical properties in rose plants grown in a glasshouse with bending technique. Leaves were lighted from the adaxial or the abaxial side during measurements, performed in four positions in the upright and bent shoots: top leaves, middle leaves, bottom leaves, and bent shoot leaves. Moreover, the effect of the irradiation on the adaxial or abaxial leaf side on whole canopy photosynthesis was estimated through model simulation. No significant differences were found in light transmission, reflection and absorption of leaves and in photosynthesis light response curves among the four positions. In all the leaf positions, light absorption, stomatal conductance and photosynthesis were higher when leaves were lighted from the adaxial compared with the abaxial side. The model showed that a substantial part of the light absorbed by the crop originated from light reflected from the greenhouse floor, and thus the abaxial leaf properties have impact on whole crop light absorbance and photosynthesis. Simulations were performed for crops with leaf area index (LAI) 1, 2 and 3. Simulation at LAI 1 showed the highest reduction of simulated crop photosynthesis considering abaxial properties; however, to a lesser extent photosynthesis was also reduced at LAI 2 and 3. The overall results showed that the model may be helpful in designing crop systems for improved light utilisation by changing lamp position or level of leaf bending and pruning.

scholarly journals Gas exchange and photosynthetic light response curves in nematode-infected tomato plants treated with Thuya occidentalis

2018 ◽  
Vol 12 (04) ◽  
pp. 583-591 ◽  
Author(s):  
Thaísa Muriel Mioranza ◽  
◽  
Adriano Mitio Inagaki ◽  
Mônica Anghinoni Müller ◽  
José Renato Stangarlin ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Light Response ◽  
Response Curves ◽  
Tomato Plants ◽  
Light Response Curves ◽  
Infected Tomato

scholarly journals Carbon assimilation through a vertical light gradient in the canopy of invasive herbs grown under different temperature regimes is determined by leaf and whole-plant architecture

AoB Plants ◽  
2020 ◽  
Vol 12 (4) ◽  
Author(s):  
Andreas Jorgensen ◽  
Brian K Sorrell ◽  
Franziska Eller
Keyword(s):  
Gas Exchange ◽  
Habitat Type ◽  
Light Response ◽  
Response Curves ◽  
Shoot Height ◽  
Iris Pseudacorus ◽  
Light Response Curves ◽  
Light Gradient ◽  
Temperature Regimes ◽  
C Assimilation

Abstract This study examined the acclimation to temperature of two globally invasive species Iris pseudacorus and Lythrum salicaria, which share the same habitat type but differ in morphology. Iris pseudacorus has long vertical leaves, allowing light penetration through the canopy, while L. salicaria has stems with small horizontal leaves, creating significant self-shading. We aimed to build a physiological understanding of how these two species respond to different growth temperatures with regard to growth and gas exchange-related traits over the canopy. Growth and gas exchange-related traits in response to low (15 °C) and high (25 °C) growth temperature regimes were compared. Plants were grown in growth chambers, and light response curves were measured with infrared gas analysers after 23–33 days at three leaf positions on each plant, following the vertical light gradient through the canopy. After 37 days of growth, above-ground biomass, photosynthetic pigments and leaf N concentration were determined. The maximum photosynthesis rate was lower in lower leaf positions but did not differ significantly between temperatures. Iris pseudacorus photosynthesis decreased with decreasing leaf position, more so than L. salicaria. This was explained by decreasing N and chlorophyll concentrations towards the leaf base in I. pseudacorus, while pigment concentrations increased towards the lower canopy in L. salicaria. Biomass, shoot height and specific leaf area increased with temperature, more so in I. pseudacorus than in L. salicaria. Light response curves revealed that L. salicaria had a higher degree of shade acclimation than I. pseudacorus, probably due to self-shading in L. salicaria. High temperature decreased C assimilation at the bottom of the canopy in L. salicaria, while C assimilation in I. pseudacorus was less affected by temperature. As vegetative growth and flowering was stimulated by temperature, the invasive potential of these species is predicted to increase under global warming.

scholarly journals Canopy Position Affects Light Response Curves for Gas Exchange Characteristics of Apple Spur Leaves

1992 ◽  
Vol 117 (3) ◽  
pp. 467-472 ◽  
Author(s):  
Richard J. Campbell ◽  
Richard P. Marini ◽  
Jeffrey B. Birch
Keyword(s):  
Gas Exchange ◽  
Dark Respiration ◽  
Incident Light ◽  
Light Response ◽  
Net Photosynthesis ◽  
Response Curves ◽  
Light Response Curves ◽  
Light Levels ◽  
Canopy Position ◽  
Gas Exchange Characteristics

Light response curves for gas exchange characteristics were developed for spur leaves of `Stayman' and `Delicious' apple (Malus domestica Borkh.) from interior, intermediate, and exterior canopy positions throughout the season. At full bloom (FB), before full leaf expansion, exterior leaves had higher maximum rates of net photosynthesis (Pn), and a statistically different Pn light response curve than the interior leaves. Intermediate leaves had intermediate Pn rates and light response curves. Pn light response curves for all three `Delicious' canopy positions differed from each other from FB + 6 weeks until the end of the season. Interior leaves had maximum Pn rates of only 50% to 60% of those for the exterior leaves from FB + 10 weeks until the end of the season. Light saturation levels were higher for the exterior leaves than for interior or intermediate leaves. Exterior leaves had a tendency throughout the season for higher quantum efficiency of Pn at subsaturating light levels than interior or intermediate leaves. Stomatal conductance was higher for the exterior than the interior or intermediate leaves of `Delicious' on all dates. Water-use efficiency was equivalent among all leaves. Exterior leaves had higher specific leaf weight, dark respiration rates, and incident light levels on all dates than interior or intermediate leaves.

A boreal forest grass with an open meadow photosynthetic strategy

1997 ◽  
Vol 75 (4) ◽  
pp. 562-567 ◽  
Author(s):  
Ken J. Greenway ◽  
Victor J. Lieffers
Keyword(s):  
Stomatal Conductance ◽  
Boreal Forest ◽  
Light Response ◽  
High Light ◽  
Stomatal Opening ◽  
Response Curves ◽  
Photosynthetic System ◽  
Calamagrostis Canadensis ◽  
Light Response Curves ◽  
Sun And Shade

Calamagrostis canadensis is present in the understory of most boreal forest mixed-wood stands and can rapidly dominate an area once the overstory is removed. The nature of the photosynthetic response to light was studied by investigating the stomatal response to cycles of high and low fluence light, and by developing photosynthetic light response curves for sun- and shade-grown plants. Photosynthetic light response curves did not differ between sun- and shade-grown plants. However, higher stomatal conductances, at all light intensities, were found in shade-grown plants. Stomatal conductance tracked changes in light under intermittent high and low fluence light. Average rates of stomatal opening after a change from low to high light were greater than closing rates (23 vs. 17 mmol m−2 s−1/min). The faster opening response was negated by a 1 – to 2-min time lag between the onset of high light and the initiation of stomatal opening. Thus the time to reach 80% of maximal response did not differ between opening or closing. The photosynthetic system of C. canadensis is not particularly well adapted to intermittent light conditions. The poor performance in the understory of this apparently meadow-adapted photosynthetic system is offset by the gain in the ability to rapidly recolonize the site after disturbance. Key words: gas exchange, stomatal conductance, Calamagrostis canadensis, non-steady state photosynthesis, variable light.

scholarly journals Fluorescence characteristics of the diatom Cylindrotheca closterium (Ehrenberg) Reimann et Lewin, 1964

2019 ◽  
Vol 4 (4) ◽  
pp. 89-92
Author(s):  
A. I. Akimov ◽  
N. Yu. Shoman ◽  
E. S. Solomonova
Keyword(s):  
Light Intensity ◽  
Functional State ◽  
Light Response ◽  
Photochemical Quenching ◽  
Response Curves ◽  
Cylindrotheca Closterium ◽  
Light Response Curves ◽  
Light Intensities ◽  
Fluorescence Characteristics ◽  
Non Photochemical Quenching

Fluorescence characteristics of the diatom Cylindrotheca closterium previously adapted to light intensities of 17, 200, and 800 μE·m−2·s−1 were investigated. Possibility of using fluorescence parameters for express score of both the algae functional state and the identification of a range of optimal light intensities for their growth was shown. The variable fluorescence coefficient (Fv/Fm) allows to evaluate in express mode the algae functional state in intensive cultivation conditions. It was shown that the maximum of Fv/Fm was of 0.65–0.7 for algae grown at light intensities of 17 and 200 μE·m−2·s−1; it decreased to 0.48–0.57 for algae adapted to light intensities of 800 μE·m−2·s−1. Light response curves of the electron transport rate, photochemical and non-photochemical quenching of chlorophyll fluorescence, and the Fv’/Fm’ coefficient values were obtained. These parameters indicate the degree of algae resistance to the light factor level. It was shown that saturating light intensity of about 200 μE·m−2·s−1 is optimal for the growth of C. closterium. The high values of yield of fluorescence per chlorophyll unit under extreme light intensity (800 μE·m−2·s−1) may indicate the degree of inactivation of part of photosystem II reaction centers.

Red spruce seedling gas exchange in response to elevated CO2, water stress, and soil fertility treatments

1994 ◽  
Vol 24 (5) ◽  
pp. 954-959 ◽  
Author(s):  
L.J. Samuelson ◽  
J.R. Seiler
Keyword(s):  
Water Stress ◽  
Gas Exchange ◽  
Soil Fertility ◽  
Net Photosynthesis ◽  
Growing Season ◽  
Red Spruce ◽  
Fertility Treatment ◽  
Sink Strength ◽  
Growth Enhancement ◽  
Growing Seasons

The interactive influences of ambient (374 μL•L−1) or elevated (713 μL•L−1) CO2, low or high soil fertility, well-watered or water-stressed treatment, and rooting volume on gas exchange and growth were examined in red spruce (Picearubens Sarg.) grown from seed through two growing seasons. Leaf gas exchange throughout two growing seasons and growth after two growing seasons in response to elevated CO2 were independent of soil fertility and water-stress treatments, and rooting volume. During the first growing season, no reduction in leaf photosynthesis of seedlings grown in elevated CO2 compared with seedlings grown in ambient CO2 was observed when measured at the same CO2 concentration. During the second growing season, net photosynthesis was up to 21% lower for elevated CO2-grown seedlings than for ambient CO2-grown seedlings when measured at 358 μL•L−1. Thus, photosynthetic acclimation to growth in elevated CO2 occurred gradually and was not a function of root-sink strength or soil-fertility treatment. However, net photosynthesis of seedlings grown and measured at an elevated CO2 concentration was still over 2 times greater than the photosynthesis of seedlings grown and measured at an ambient CO2 concentration. Growth enhancement by CO2 was maintained, since seedlings grown in elevated CO2 were 40% larger in both size and weight after two growing seasons.

Photosynthetic light-response curves

Planta ◽  
1993 ◽  
Vol 189 (2) ◽  
Author(s):  
E. �gren ◽  
J.R. Evans
Keyword(s):  
Light Response ◽  
Response Curves ◽  
Light Response Curves
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