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1

Digitale Medien

Stomatal response to environment and a possible interrelation between stomatal effects on transpiration and CO2 assimilation (1980)

HALL, A. E. ; SCHULZE, E.-D.

Oxford, UK : Blackwell Publishing Ltd

Plant, cell & environment 3 (1980), S. 0

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ISSN: 1365-3040

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: Abstract It had been hypothesized that if daily CO2 assimilation is to be maximized at a given level of daily transpiration, stomatal apertures should change during the day so that the gain ratio (∂A/∂g)/(∂E/∂g) remains constant. These partial differentials describe the sensitivity of assimilation rate (A) and transpiration rate (E) to changes in stomatal conductance (g). Experiments were conducted to determine whether stomata respond to environment in a manner which results in constant gain ratios.Gas–exchange measurements were made of the stomatal and photosynthetic responses of Vigna unguiculata L. Walp. in controlled environments. Leaf conductance to water vapour responded to step changes in temperature and humidity so that for different steady-state conditions the gain ratio remained constant on all but one day. Depletion of water in the root zone resulted in day-to-day increases in gain ratio which were correlated with decreases in maximum leaf conductance to water vapour. The significance of the results for plant adaptation and stomatal mechanisms, and methods for measuring the gain ratio, are discussed.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/1365-3040.ep11587040

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2

Digitale Medien

ADAPTATION OF PLANTS TO WATER AND HIGH TEMPERATURE STRESS (Book). (1982)

Schulze, E. -D.

Oxford, UK : Blackwell Publishing

Plant, cell & environment 5 (1982), S. 0

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ISSN: 1365-3040

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/1365-3040.ep11572630

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3

Digitale Medien

PLANT PRODUCTION AND MANAGEMENT UNDER DROUGHT CONDITIONS (Book). (1984)

Schulze, E.-D.

Oxford, UK : Blackwell Publishing

Plant, cell & environment 7 (1984), S. 0

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ISSN: 1365-3040

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/1365-3040.ep11616245

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4

Digitale Medien

Carbon, water and nutrient relations of two mistletoes and their hosts: A hypothesis (1984)

SCHULZE, E.-D. ; TURNER, N. C. ; GLATZEL, G.

Oxford, UK : Blackwell Publishing Ltd

Plant, cell & environment 7 (1984), S. 0

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ISSN: 1365-3040

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: Abstract. The carbon, water and nutrient relations of the xylem parasites Loranthus europaeus and Viscum laxum and their respective hosts. Quercus robur and Pinus sylvestris, were followed throughout clear days in July in order to study water and nutrient interactions in a simple system in which the plant growth depends on the host for its water and nutrients. At similar quantum flux densities, temperatures and vapour pressure deficits, the mistletoes had higher rates of transpiration and lower leaf water potentials than their hosts, but similar rates of CO2 assimilation. Based on measurements of the nutrient content of the xylem and on seasonal measurements of the biomass and the tissue nutrient content, the present study suggests that the high rates of transpiration may be necessary for the parasites to take up sufficient nitrogen from the xylem of the host for production of biomass (leaves, fruits and stems).

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/1365-3040.ep11589756

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5

Digitale Medien

The effect of nitrogen supply on growth and water-use efficiency of xylem-tapping mistletoes (1984)

Schulze, E. -D. ; Ehleringer, J. R.

Springer

Planta 162 (1984), S. 268-275

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ISSN: 1432-2048

Schlagwort(e): Host parasite interactions ; Mistletoe ; Nutrient relations (mistletoes) ; Phoradendron ; Water relations (mistletoes)

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Abstract Xylem-tapping mistletoes are known to have normally a higher rate of transpiration and lower water-use efficiency than their hosts. The relationships between water relations, nutrients and growth were investigated for Phoradendron juniperinum growing on Juniperus osteosperma (a non-nitrogen-fixing tree) and for Phoradendron californicum growing on Acacia greggii (a nitrogen-fixing tree). Xylem sap nitrogen contents were approximately 3.5 times higher in the nitrogen-fixing host than in the non-nitrogen-fixing host. The results of the present study show that mistletoe growth rates were sevenfold greater on a nitrogen-fixing host. At the same time, however, the differences in water-use efficiency between mistletoes and their hosts, which were observed on the non-nitrogen-fixing host did not exist when mistletoes were grown on hosts with higher nitrogen contents in their xylem sap. Growth rates and the accumulation of N, P, K, and Ca as well as values for carbon-isotope ratios of mistletoe tissues support the hypothesis that the higher transpiration rates of mistletoes represent a nitrogen-gathering mechanism.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00397449

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6

Digitale Medien

Short-term and long-term effects of plant water deficits on stomatal response to humidity in Corylus avellana L. (1979)

Schulze, E.-D. ; Küppers, M.

Springer

Planta 146 (1979), S. 319-326

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ISSN: 1432-2048

Schlagwort(e): Humidity response ; Stomata ; Transpiration ; Water potential ; Water stress

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Abstract Short-term (hours) changes in plant water status were induced in hazel (Corylus avellana L.) by changing the evaporative demand on a major portion of the shoot while maintaining a branch in a constant environment. Stomatal conductance of leaves on the branch was influenced little by these short-term changes in water status even with changes in leaf water potential as great as 8 bars. Long-term (days) changes in plant water status were imposed by soil drying cycles. Stomatal conductance progessively decreased with increases in long-term water stress. Stomata still responded to humidity with long-term water stress but the range of the conductance response decreased. Threshold responses of stomata to leaf water potential were not observed with either short-term or long-term changes in plant water status even when leaves wilted. It is suggested that concurrent measurements of plant water status may not be sufficient for explaining stomatal and other plant responses to drought.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00387804

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7

Digitale Medien

Spacial distribution of photosynthetic capacity and performance in a mountain spruce forest of northern Germany (1977)

Fuchs, M. ; Schulze, E. -D. ; Fuchs, M. I.

Springer

Oecologia 29 (1977), S. 329-340

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ISSN: 1432-1939

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Summary Net photosynthesis of Picea abies was measured in a spruce forest in northern Germany with temperature- and humidity-controlled cuvettes in 4 different crown layers on shoots of different ages. These measurments were performed such that temperature and humidity either followed ambient conditions or were kept constant. Annual courses of light-, temperature-, and humidity-related net photosynthesis were determined. Spruce had a remarkably constant rate of CO2 uptake from April to September for 1-year and older needles. Light saturation was achieved at 25 klx. Current year needles had the highest rates of CO2 uptake in early summer, but these rates decreased by autumn. Photosynthetic capacity decreased with needle age and, on a dry weight basis, it was higher in the shade than in the sun crown. The temperature optimum was between 13 and 23° C. Photosynthesis in spruce decreased when air humidity was low. The effect of the natural weather conditions on photosynthetic capacity was determined. The habitat is characterized by a high frequency of low light intensities (75% of total daytime below 20 klx) and cool temperatures (80% of daytime between 9 and 21° C). Low air humidity was only present when light intensities were high. The major limiting factor for production was low light intensities, which reduced photosynthetic capacity in the sun crown to 42% below maximum possible rates. Adverse temperatures reduced CO2 uptake by 28% and large water vapor pressure deficits reduced rates by only 2% compared with maximum possible rates. The limited adaptation to light is discussed.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00345806

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8

Digitale Medien

Seasonal and diurnal courses of water relations of the arido-active plant Hammada scoparia in the Negev desert (1975)

Kappen, L. ; Oertli, J. J. ; Lange, O. L. ; [weitere]

Springer

Oecologia 21 (1975), S. 175-192

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ISSN: 1432-1939

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Summary The photosynthesizing branches of Hammada scoparia, one of the typical dwarf shrubs of the Negev desert, undergo a seasonal change from succulent to xeromorphic anatomy. This trend is accompanied by a marked decrease of water content and of total water Ψ plant and osmotic Ψ π plant potential. Irrigated plants do not show such transitions. The daily courses of Ψ plant and Ψ π plant showed minima around noon and a tendency for maxima before sunrise. Turgor pressure Ψ p plant reached minima around noon and became negative (until ca.-10 bars). Generally, Ψ plant decreases with increasing water vapour concentration difference between plant and air (WD) in the first half of the day, and in the second half the reversal of this trend occurs. Mostly smaller increments of Ψ plant were correlated with larger increases in WD which lead to the conclusion that stomates closed enough to maintain transpiration at a constant value. Non-irrigated and irrigated plants showed different hysteresis loops of relation between Ψ plant and WD. Regulatory reduction of transpiration appears largely independently of Ψ plant which is in spring and with irrigated plants on a high level, with non-irrigated plants in summer on a low level. In summer the continous but decreasing drop of Ψ plant with increasing WD was interpreted as caused by a change in soil or root resistance. Independent of the seasonal state and of the Ψ plant level, H. scoparia regulates its water status within limited ranges of Ψ p plant changes: the irrigated plants on a higher level, the non-irrigated on a lower level of Ψ p plant . The water contents of the tissues of H. scoparia are linearily related to Ψ plant as well as Ψ p plant . Steeper slopes with non-irrigated plants in summer than with spring palnts and with irrigated plants during the whole season signify that in the latter a certain increment in turgor pressure corresponds to a large gain in water content while in the non-irrigated summer plants it varies only little for an identical change in Ψ p plant . This behaviour of non-irrigated wild plants apparently is due to the change of the elastic properties of the tissues in the assimilating branches.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00345559

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9

Digitale Medien

The role of air humidity and temperature in controlling stomatal resistance of Prunus armeniaca L. under desert conditions (1975)

Schulze, E. -D. ; Lange, O. L. ; Evenari, M. ; [weitere]

Springer

Oecologia 19 (1975), S. 303-314

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ISSN: 1432-1939

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Summary Measurements of CO2 and water vapor exchange were performed on Prunus armeniaca L. with humidity- and temperature-controlled chambers under the climatic conditions of a desert habitat. In apricot, the stomatal response to changes in temperature and water-vapor concentration difference between leaf and air (WD) significantly determined the rates of gas exchange during the day (parts I and II). The effect of climate-controlled stomatal response on the transpiration/net photosynthesis (T/P)-ratio was analyzed and simulated using experiments conducted at constant temperature and/or humidity conditions for input parameters. The measured values of the T/P-ratio at naturally varying conditions of humidity and temperature were compared with calculated results of a model in which it was assumed, (1) that stomata and photosynthetic activity are not affected by air humidity and temperature, (2) that the stomata only respond with a constant photosynthetic activity to changes in WD, and (3) that the stomata respond to both, leaf temperature and air humidity with a constant photosynthetic activity. These simulations facilitated an analysis of the naturally observed changes in the T/P-ratio. The calculated T/P-ratios were very small if the simulation assumed that stomata only respond to WD at a constant photosynthetic activity. These low predicted values of the T/P-ratio were not obtained under natural conditions, since an increase in WD during the day was correlated with a temperature rise which tended to open stomata and change the photosynthetic activity. Humidity induced stomatal closure did appear to substantially reduce T/P-ratios. The measured T/P-ratio changed considerably during the year. The lowest T/P-ratios were obtained in the middle of the dry season at a time when stomata responded strongly to air humidity and when optimum of photosynthesis was reached at high temperatures. The daily average T/P-ratio calculated from the daily sum of P and T showed little change during the seasons. A high T/P-ratio was also observed at reduced rates of gas exchange. The T/P-ratios of apricot were compared with different species in different environments.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00348106

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10

Digitale Medien

The role of air humidity and leaf temperature in controlling stomatal resistance of Prunus armeniaca L. under desert conditions (1975)

Schulze, E. -D. ; Lange, O. L. ; Kappen, L. ; [weitere]

Springer

Oecologia 18 (1975), S. 219-233

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ISSN: 1432-1939

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Summary The gas exchange of the apricot (Prunus armeniaca L.) growing in the runoff farm at Avdat (Negev, Israel) was measured during its growing period using temperature- and humidity-controlled chambers. Water potentials of the xylem were measured with a pressure bomb, and the mesophyll internal CO2 concentration was calculated from simultaneous measurements of net photosynthesis and transpiration. The daily changes in water potential Ψ had only little effect on the daily course of stomatal resistance. The early morning peak of CO2 uptake was reached when Ψ had already dropped to very low values. On dry days, Ψ and the relative water content of the leaf were improved at noon during the time of stomatal closure. On humid days, Ψ dropped to very low values (43.5 bar) at a high transpiration rate without causing stomatal closure, as much as on the dry days when stomata where more closed at less water stress. The observed changing sensitivity of the stomata to changes in air humidity during the season is related to the water status in the plant. This change is possibly caused by a long-term effect of stress in this habitat. The daily changes in stomatal diffusion resistance did not consistently correlate with changes of the CO2 concentration in the intercellular air spaces. In the morning a decreasing internal CO2 concentration was even inversely correlated to the stomatal response. In the afternoon the effect of an increasing internal CO2 concentration and the effect of external climate on stomatal response could be additive. However, at the time, when CO2 uptake reached a second peak in the afternoon the same value of diffusion resistance is reached at very different levels of internal CO2 concentration as compared to the morning. For the regulation of the diffusion resistance in apricot under the natural conditions, the effects of plant internal control mechanisms are overruled and/or modified by the external climatic factors of air humidity and temperature. The significance of the climate-controlled stomatal response for the existence and cultivation of this plant species in an arid habitat is discussed.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00345424

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