Seasonal ecophysiology and leaf morphology of four successional Pennsylvania barrens species in open versus understory environments

1993 ◽  
Vol 23 (2) ◽  
pp. 181-189 ◽  
Author(s):  
Brian D. Kloeppel ◽  
Marc D. Abrams ◽  
Mark E. Kubiske
Keyword(s):  
Gas Exchange ◽  
Stomatal Density ◽  
Net Photosynthesis ◽  
Leaf Conductance ◽  
Response Curves ◽  
Tissue Water ◽  
Specific Leaf Mass ◽  
Leaf Mass ◽  
Quercus Spp ◽  
Open Versus

Seasonal net photosynthesis, water relations, and leaf structure were measured in co-occurring saplings of Quercusvelutina Lam., Quercusprinus L., Sassafrasalbidum (Nutt.) Nees, and Acerrubrwn L. from adjacent open and understory sites in the central Pennsylvania barrens, United States. Saplings of all species exhibited significant physiological and morphological plasticity, which included greater area-based photosynthesis, leaf conductance, water-use efficiency, stomatal density, specific leaf mass, and leaf thickness on the open site. However, only Q. velutina had greater net photosynthesis in the open versus understory when photosynthesis was expressed on a mass basis. The earlier successional Quercus spp. and S. albidum exhibited higher diurnal and seasonal gas exchange in the open than the later successional A. rubrum, although all species exhibited significant diurnal declines in photosynthesis. Quercus spp. exhibited a 56–62% greater decrease in diurnal water potential compared with S. albidum and A. rubrum in both the open and understory. Sassafras maintained high gas-exchange rates in the open without experiencing large diurnal tissue water deficits. Seasonal variations in net photosynthesis and leaf conductance were significantly correlated with each other and with specific leaf mass. Light-response curves predicted greater saturating light levels and greater rates of maximum photosynthesis in the early successional species versus A. rubrum, but similar light compensation values in all species. The results of this study suggest that each species displayed many similar and unique adaptations and responses to varying light and water availability in the barrens environment.

Inheritance of temperature adaptation in intra- and inter-specific Populus crosses

1992 ◽  
Vol 22 (1) ◽  
pp. 62-67 ◽  
Author(s):  
Allan P. Drew ◽  
James A. Chapman
Keyword(s):  
Interspecific Hybrid ◽  
Response Curve ◽  
Stomatal Density ◽  
Temperature Response ◽  
Net Photosynthesis ◽  
Leaf Conductance ◽  
Temperature Adaptation ◽  
Optimum Rate ◽  
Intraspecific Hybrid

Populustrichocarpa Torr. & Gray from Alaska was crossed with the same species from a Montana population, and the resulting intraspecific hybrid was crossed with Populusdeltoides Bartr. ex Marsh, from Minnesota. Ramets from the five parents and hybrids were tested for the response of leaf conductance to temperature of the prior night. Leaf stomatal density and size were determined and net photosynthesis was measured between 15 and 40 °C for all clones. Alaska and Montana sources of P. trichocarpa and their hybrid showed mildly sensitive leaf conductance responses to 10 °C nights and comparable responses to 4 °C nights. The Alaska parent had an optimum rate of net photosynthesis at 20 °C, 10 °C lower than that of its hybrid, but the Montana parent's temperature response curve was less clearly defined. Although the P. trichocarpa hybrid was intermediate or similar to both parents in temperature adaptation, in stomatal density, size, and Q-ratio it was more similar to the Alaska parent. The P. deltoides parent and its interspecific hybrid exhibited a sensitive pattern of leaf conductance response to cool nights. The hybrid had a net photosynthetic temperature response curve that closely paralleled that of the P. deltoides parent, yet rates were lower, between 20 and 35 °C, in both compared with the P. trichocarpa parent. The interspecific hybrid more closely resembled the P. deltoides than the P. trichocarpa parent in overall temperature adaptation and had morning leaf conductance higher than that of both. Stomatal density and size were more unlike the P. deltoides than the P. trichocarpa parent, and the Q-ratio of the hybrid was intermediate to that of the parents.

High levels of anatomical and physiological leaf plasticity of Ocotea odorifera (Lauraceae) in response to different radiation intensities

Botany ◽  
2021 ◽  
Vol 99 (1) ◽  
pp. 23-32
Author(s):  
Gabriele Marques Leme ◽  
Flavio Nunes Ramos ◽  
Fabricio José Pereira ◽  
Marcelo Polo
Keyword(s):  
Gas Exchange ◽  
Stomatal Density ◽  
Leaf Gas Exchange ◽  
Net Photosynthesis ◽  
Forest Edge ◽  
Forest Fragments ◽  
Gas Exchange Parameters ◽  
Fragmented Forest ◽  
Forest Interior ◽  
Leaf Plasticity

We investigated morpho-physiological plasticity in the leaves of Ocotea odorifera trees growing under different environmental conditions in a fragmented forest. Microclimatic data were collected in a pasture matrix, forest edge, and forest interior in three Atlantic Forest fragments. Leaf gas exchange, as well as leaf anatomy in paradermal and transversal sections, were evaluated in individuals in these environments. Radiation intensity and temperature had higher effects in the pasture matrix compared with the forest interior and forest edge. However, internal portions of the canopy did not exhibit significant variation in radiation or temperature. External canopy leaves exhibited higher net photosynthesis in plants from the pasture matrix, but there was higher net photosynthesis for internal leaves from the shaded forest interior. Variation in net photosynthesis and other gas-exchange parameters were related to thinner shade leaves in forest interior individuals, and internal leaves with lower stomatal density. Although the pasture matrix, forest edge, and forest interior experienced differences in light and temperature, leaf position in the canopy produced microclimatic variations, which modified gas exchange and anatomy. Thus, O. odorifera shows the potential for reforestation programs because of its high leaf plasticity, which will enable it to overcome variations in light and temperature.

An Empirical Model of Net Photosynthesis and Leaf Conductance for the Simulation of Diurnal Courses of CO2 and H2O Exchange

1985 ◽  
Vol 12 (5) ◽  
pp. 513 ◽  
Author(s):  
M Kuppers ◽  
ED Schulze
Keyword(s):  
Gas Exchange ◽  
Empirical Model ◽  
Climatic Factors ◽  
Net Photosynthesis ◽  
Co2 Assimilation ◽  
Leaf Conductance ◽  
Co2 Uptake ◽  
Diurnal Courses ◽  
Humidity Response ◽  
Steady State Responses

An empirical model of CO2 uptake and water loss of leaves is established using steady-state responses of gas exchange to climatic factors as input. From the model the response surface of net CO2 assimilation and leaf conductance to climate can be derived. The model consists of two submodels, one describing the response of CO2 uptake to light and temperature, the other describing the response of leaf conductance to temperature and humidity. Both submodels are joined via the linear relationship between CO2 uptake and leaf conductance at short-term (minutes) variation of irradiance. From the humidity response of leaf conductance and the 'demand function' (Raschke 1979) of CO2 uptake in the mesophyll, the effect of stomata on the diffusion of CO2 between leaf and air is determined. The model is tested by comparing measured and calculated diurnal courses of gas exchange for two plants of Pinus silvestris, differing in photosynthetic capacity due to different levels of magnesium nutrition. Applications and limitations of the model are discussed.

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.

scholarly journals Isoprene emission and photosynthesis during heatwaves and drought in black locust

2017 ◽  
Vol 14 (15) ◽  
pp. 3649-3667 ◽  
Author(s):  
Ines Bamberger ◽  
Nadine K. Ruehr ◽  
Michael Schmitt ◽  
Andreas Gast ◽  
Georg Wohlfahrt ◽  
...  
Keyword(s):  
Heat Stress ◽  
Drought Stress ◽  
Stomatal Conductance ◽  
Gas Exchange ◽  
Black Locust ◽  
Leaf Gas Exchange ◽  
Net Photosynthesis ◽  
Response Curves ◽  
Drought Treatment ◽  
Isoprene Emission

Abstract. Extreme weather conditions like heatwaves and drought can substantially affect tree physiology and the emissions of isoprene. To date, however, there is only limited understanding of isoprene emission patterns during prolonged heat stress and next to no data on emission patterns during coupled heat–drought stress or during post-stress recovery. We studied gas exchange and isoprene emissions of black locust trees under episodic heat stress and in combination with drought. Heatwaves were simulated in a controlled greenhouse facility by exposing trees to outside temperatures +10 °C, and trees in the heat–drought treatment were supplied with half of the irrigation water given to heat and control trees. Leaf gas exchange of isoprene, CO2 and H2O was quantified using self-constructed, automatically operating chambers, which were permanently installed on leaves (n = 3 per treatment). Heat and combined heat–drought stress resulted in a sharp decline of net photosynthesis (Anet) and stomatal conductance. Simultaneously, isoprene emissions increased 6- to 8-fold in the heat and heat–drought treatment, which resulted in a carbon loss that was equivalent to 12 and 20 % of assimilated carbon at the time of measurement. Once temperature stress was released at the end of two 15-day-long heatwaves, stomatal conductance remained reduced, while isoprene emissions and Anet recovered quickly to values of the control trees. Further, we found that isoprene emissions covaried with Anet during nonstress conditions, while during the heatwaves, isoprene emissions were not related to Anet but to light and temperature. Under standard air temperature and light conditions (here 30 °C and photosynthetically active radiation of 500 µmol m−2 s−1), isoprene emissions of the heat trees were by 45 % and the heat–drought trees were by 27 % lower than in control trees. Moreover, temperature response curves showed that not only the isoprene emission factor changed during both heat and heat–drought stress, but also the shape of the response. Because introducing a simple treatment-specific correction factor could not reproduce stress-induced isoprene emissions, different parameterizations of light and temperature functions are needed to describe tree isoprene emissions under heat and combined heat–drought stress. In order to increase the accuracy of predictions of isoprene emissions in response to climate extremes, such individual stress parameterizations should be introduced to current BVOC models.

scholarly journals A Study of Photosynthetic Activities of Eight Asparagus Genotypes under Field Conditions

1999 ◽  
Vol 124 (1) ◽  
pp. 61-66 ◽  
Author(s):  
Yuyu Bai ◽  
John F. Kelly
Keyword(s):  
Photosynthetic Activity ◽  
Net Photosynthesis ◽  
Gas Analysis ◽  
Asparagus Officinalis ◽  
Specific Leaf Mass ◽  
Leaf Mass ◽  
Analysis System ◽  
Whole Plants ◽  
Photosynthetic Activities ◽  
Daily Changes

Net photosynthesis from whole plants of eight asparagus (Asparagus officinalis L.) genotypes was measured at two locations in an open infrared gas analysis system. Measurements started at about the completion of full fern growth, which occurred at the end of July and lasted through the season until fern senescence in late September. Net photosynthesis of the eight genotypes ranged from 15.67 to 27.79 μmol·m-2·s-1. Significant differences (P < 0.1) in net photosynthesis were found among the eight genotypes. Both yield and specific leaf mass (SLM) were correlated significantly with net photosynthesis. We suggest that specific leaf mass can be used as a criterion for selecting genotype of high photosynthetic ability. Daily photosynthetic rate patterns were studied and appear to be related to daily changes of stomatal conductance. Seasonal changes of asparagus' photosynthetic activity were studied. High photosynthetic activity was observed from July through August. Photosynthetic activity decreased greatly in September along with the fern maturation and unfavorable changes in environmental conditions.

scholarly journals Morpho-physiological responses of cowpea leaves to salt stress

2006 ◽  
Vol 18 (4) ◽  
pp. 455-465 ◽  
Author(s):  
Claudivan F. Lacerda ◽  
José O. Assis Júnior ◽  
Luiz C. A. Lemos Filho ◽  
Teógenes S. de Oliveira ◽  
Francisco V.A. Guimarães ◽  
...  
Keyword(s):  
Salt Stress ◽  
Leaf Area ◽  
Nutrient Solution ◽  
Net Photosynthesis ◽  
Experimental Period ◽  
Specific Leaf Mass ◽  
Leaf Mass ◽  
Whole Plant ◽  
Plant Acclimation ◽  
Leaf Succulence

The effect of salt stress of known intensity and duration on morpho-physiological changes in leaves of different ages from cowpea [Vigna unguiculata (L.) Walp.] plants was studied, aiming for a better understanding of the acclimation process of the whole-plant. Seeds were sown in vermiculite and seedlings were transferred to plastic trays containing aerated nutrient solution, and kept in a greenhouse. When the first trifoliate leaf emerged the seedlings were transplanted into 3 L plastic pots containing aerated nutrient solution. Salt additions started 5 d later, and the salt-treated plants received 25 mmol L-1 per day until reaching a final concentration of 75 mmol L-1. During the experimental period primary leaves and the 1st, 2nd, and 3rd trifoliate leaves were used for measurements of net photosynthesis, leaf area, leaf succulence, specific leaf mass, ions and chlorophyll concentrations. Growth analysis of the whole-plant was performed at the end of the experimental period. Salinity did not affect net photosynthesis, but reduced dry mass production and the number of lateral branches. Leaf concentrations of Na+, Cl-, K+ and P increased in salt-stressed plants, but these responses were dependent upon stress duration and leaf age. The higher concentration of potentially toxic ions (Na+ and Cl-) in older leaves could contribute to the reduced ion accumulation in growing tissues, but the tendency of K and P accumulation in leaves appeared to be the result of reduced re-translocation, i.e., not related to plant acclimation. Salinity also increased the source/sink ratio, leaf succulence, specific leaf mass, and chlorophyll accumulation per unit of leaf area, suggesting that the observed changes could be part of an integrated mechanism of whole-plant acclimation to salt stress.

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.

Photosynthesis and Transpiration in Damaged and Undamaged Spruce Trees

1996 ◽  
Vol 51 (3-4) ◽  
pp. 200-210 ◽  
Author(s):  
Aloysius Wild ◽  
Peter Sabel ◽  
Lucia Wild-Peters ◽  
Ursula Schmieden
Keyword(s):  
Gas Exchange ◽  
Water Potential ◽  
Natural Habitat ◽  
Late Summer ◽  
Net Photosynthesis ◽  
Diurnal Course ◽  
Physiological Homeostasis ◽  
Use Efficiency ◽  
Needle Loss ◽  
Light Saturation Curves

Abstract The investigations presented here focus on the CO2/H2O gas exchange in damaged and undamaged spruce trees while using open-air measurements as well as measurements under defined conditions in the laboratory. The studies were performed at two different sites in the Hunsrück and the Westerwald mountains. In the laboratory the CO2/H2O gas exchange was measured on detached branches under controlled conditions in the course of two years. CO2 saturation curves were also generated. In addition CO2 compensation points were deter­ mined employing a closed system. In the natural habitat diurnal course measurements of photosynthesis and transpiration as well as light-saturation curves for photosynthesis were performed. In parallel with the photosynthesis and transpiration measurements, measurements of the water potential were taken at both locations. The photosynthetic capacity and transpiration rate show a typical annual course with pronounced maxima in spring and late summer and minima in summer and winter. The needles of the damaged trees exhibit higher transpiration rates and a distinct reduction in photosyn­ thesis than the needles of the undamaged trees during two seasons. The diurnal course measurements of net photosynthesis and transpiration show a maximum in photosynthesis and transpiration in the afternoon in May and September, but a characteristic midday depression in July. Photosynthesis was markedly lower and transpiration higher in the needles of the damaged trees. The damaged trees show a lower increase in the light and CO2 saturation curves and higher CO2 compensation points as compared to the undamaged trees. The water potential reaches much lower values during the course of the day in needles of the dam­ aged trees. The reduction of the photosynthetic rate on one hand and the increase in transpiration on the other hand result in an extreme lowering of the water use efficiency in photosynthesis. The damage to the thylakoid membranes and to the guard cells obviously results in a pro­ found disturbance of the physiological homeostasis of the needles and could thus lead to premature needle loss.

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