Showing papers by "Ernst Detlef Schulze published in 1976"

Current Perspectives of Steady-state Stomatal Responses to Environment

Abstract: Plant responses to environment are frequently influenced by stomatal functioning, through effects on plant water use, the development of plant water deficits, net photosynthesis, and temperature relations. In ecophysiology, predicting stomatal responses to environment and relating these responses to the functioning and physical state of plants are important objectives. Qualitative and quantitative differences in stomatal behavior between plant species and ecotypes, or at different phenological stages play important roles in plant performance and adaptation.

Water and plant life : problems and modern approaches

Abstract: 1 Fundamentals of Plant Water Relations- Preface- A The Structure of Water in the Biological Cell- I Introduction- II Evidence for Structured Aqueous Boundary Layers- III Thermal Anomalies in Biological Tissues- IV Properties of Aqueous Electrolyte Layers- V Conclusions- References- B The States of Water in the Plant-Theoretical Consideration- I Introduction- II Physiological Importance of Processes and Properties Involving Water- III Metabolism and Water Relations- IV Conclusions- References- C The Soil-Plant-Atmosphere Continuum- I Introduction- II Description of the Turgor Pressure as a Function of Environmental Variables- III Water Flow in the SPAC as a Link Between Plant and Environment- IV The Solute-free Transport System- V Effects of Solutes in the SPAC- VI Changes in Resistances or Potential Differences- VII Conclusions- References- D The Water Status in the Plant-Experimental Evidence- I Introduction- II Current Methods for the Determination of Total Water Potential and Its Components- III The Range of Water Potentials Hitherto Determined and the Continuum Conditions Favoring Extreme Values- IV The Component Potentials Adjusting Total Water Potential in the Plant Body: Ranges and Changes- V Why does Water Potential in a Plant Change?- VI Conclusions- References- 2 Water Uptake and Soil Water Relations- Preface- A Root Extension and Water Absorption- I Introduction- II Water Movement Through the Soil-Plant-Atmosphere Continuum: Limitations in the Liquid Phase- III Root Extension and Facilitation of Water Uptake in Unexplored Soil Regions- IV Root Extension Within the Rooted Zone: A Case for Avoidance of Localized Rhizospheric Resistances- V Conclusions- References- B Resistance to Water Flow in the Roots of Cereals- I Introduction- II Anatomy of Cereal Roots- III Zone of Water Absorption- IV Forces Causing Flow of Water- V Resistance to Flow- VI Effect of Root Resistance on Withdrawal of Water from the Soil- VII Conclusions- References- C Soil Water Relations and Water Exchange of Forest Ecosystems- I Introduction- II Water Balance- III Fundamental Equations and Principles- IV Simulation of Evapotranspiration and Percolation- V Conclusions- References- 3 Transpiration and Its Regulation- Preface- A Energy Exchange and Transpiration- I Introduction- II Gas Diffusion- III Energy Balance- IV Transpiration- V Wind Speed Influence- VI Leaf Temperature Affected by Transpiration- VII Conclusions- References- B Water Permeability of Cuticular Membranes- I Introduction- II Cuticular Transpiration-Early Observations and Hypotheses- III The Concept of the Polar Pathway Through Lipid Membranes- IV Conclusions- References- C Physiological Basis of Stomatal Response- I Introduction- II Biochemical Processes Leading to Movement- III Conclusions: Ability of the Mechanism to Explain the Known Facts- References- D Current Perspectives of Steady-state Stomatal Responses to Environment- I Introduction- II Measurement of Stomatal Responses to Environment- III Steady-state Stomatal Responses to Environment- IV Stomatal Responses to Diurnal Changes in Environment- V Conclusions and Future Research Directions- References- E Water Uptake, Storage and Transpiration by Conifers: A Physiological Model- I Introduction- II Description of the Model- III Applications- IV Conclusions- References- 4 Direct and Indirect Water Stress- Preface- A Water Stress, Ultrastructure and Enzymatic Activity- I Introduction- II Effects of Water Stress on Hydrolytic Enzymatic Activity- III Effects of Water Stress on the Ultrastructure of the Cell- IV Relationships of Ultrastructural Alteration and Hydrolytic Enzyme Decompartmentation and Activation, with Alteration of Chloroplasts and Mitochondria Metabolism- V Conclusions- References- B Water Stress and Hormonal Response- I Introduction- II Endogenous Hormonal Changes Due to Water Stress- III The Physiological Significance of Hormonal Effects- IV A Hypothetical Model for the Role of Hormones in Plant Adaptation to Water Stress- V Conclusions- References- C Carbon and Nitrogen Metabolism Under Water Stress- I Introduction- II Carbon Metabolism Under Water Stress- III Nitrogen Metabolism Under Water Stress- IV Biochemical Aspects of Desiccation Resistance- V Conclusions- References- D Water Stress During Freezing- I Introduction- II Frost Injury- III Frost Resistance- IV Conclusions- References- E Cell Permeability and Water Stress- I Introduction- II Principles of Cell Permeability- III Quantitative Determination of Permeability- IV Alterations of Cell Permeability by the Plant Water Deficit- V Possible Mechanisms for Changes in Cell Permeability by Plant Water Stress- VI Conclusions- References- F Water Stress and Dynamics of Growth and Yield of Crop Plants- I Introduction- II Overview of Growth and Yield as Affected by Water- III Some Behavior Observed in the Field- IV Concluding Remarks- References- 5 Water Relations and CO2 Fixation Types- Preface- A Crassulacean Acid Metabolism (CAM): CO2 and Water Economy- I Introduction- II Carbon Metabolism of CAM Plants- III Gas Exchange of CAM Plants- IV Ecological Aspects of CAM- V Conclusions- References- B Balance Between C3 and CAM Pathway of Photosynthesis- I Introduction- II Adaptation to Salinity- III Environmental Control of Photosynthetic Pathways- IV Regulation of the Balance between C3 and CAM- V Ecological Aspects- References- C C4 Pathway and Regulation of the Balance Between C4 and C3 Metabolism- I Introduction- II Carbon Metabolism of C4 Plants- III General Characteristics of C4 Plants- IV Factors Affecting Shift- V Natural C3-C4 Intermediates- VI Ecological Implications- VII Conclusions- References- D Ecophysiology of C4 Grasses- I Introduction- II Environmental Conditions- III Physiological Responses to Environmental Conditions- IV Ecological Implications- V Conclusions: Future Research- References- 6 Water Relations and Productivity- Preface- A The Use of Correlation Models to Predict Primary Productivity from Precipitation or Evapotranspiration- I Introduction- II Construction of Correlation Models and Geographical Patterns (Surfaces)- III Some Examples of Correlation Models of Net Primary Productivity versus Water Factor- IV Accuracy of Correlation Models- V Conclusions- References- B The Use of Simulation Models for Productivity Studies in Arid Regions- I Introduction- II The Structure of the Model- III Description of the Model ARID CROP- IV Validation of the Model- V Application of the Model- VI Conclusions- References- C Irrigation and Water Use Efficiency- I Introduction- II Efficiency of Water Supply- III Transpiration/Photosynthesis Relationships- IV Some Agronomic Aspects- V Conclusions- References- D Estimating Water Status and Biomass of Plant Communities by Remote Sensing- I Introduction- II Water Stress, Reflectance, and Temperature of Single Leaves- III Reflectance and Biomass of Communities- IV Conclusions- References- E Plant Production in Arid and Semi-Arid Areas- I Introduction- II Survey of Phytomass, Net Annual and Relative Annual Production of Some Main Vegetation Units of the Globe- III Phytomass and Production of Some Arid and Semi-Arid Vegetation Units and their Annual Fluctuations- IV Permanent Phytomass- V Potential Production- VI Recovery- VII Conclusions- References- F Water Content and Productivity of Lichens- I Introduction- II Productivity of Lichens- III Water Relations of Lichens- IV Thallus Water Content and Physiological Response- V Conclusions: Water Relations and Productivity-a Synthesis- References- 7 Water and Vegetation Patterns- Preface- A Water Relations and Alpine Timberline- I Introduction- II Water Relations of Trees at the Timberline- III Causes of Winter Desiccation of Trees at Timberline- IV Conclusions: Ecophysiological Analysis of the Alpine Timberline and its Dynamics- References- B The Water Factor and Convergent Evolution in Mediterranean-type Vegetation- I Introduction- II Environmental Stresses in Mediterranean-type Climates- III Ecological Significance of Leaf Structure- IV Seasonal Patterns of Photosynthesis, Water Relations and Productivity- V Evolutionary Consequences of Mediterranean-type Environmental Stresses- VI Conclusions- References- C The Water-Photosynthesis Syndrome and the Geographical Plant Distribution in the Saharan Deserts- I Introduction- II The Floristic and Physiognomic Aspects of the Sahara- III The Water-Photosynthesis Syndrome in the Northern and in the Southern Sahara- IV Holarctic and Palaeotropic Constitution Types- V Conclusions- References- Index of Plant Species

Distribution and control of photosynthetic pathways in plants growing in the Namib Desert, with special regard to Welwitschia mirabilis Hook. Fil.

Abstract: The present study investigates the physioIogical bases of species which compose the typical vegetation types of the Northern Namib: the savannas, the subtropical grasslands and the succulent deserts. The relative role in terms of vegetation cover and species diversity of the various pathways of photosynthetic production is determined and the environmental factors responsible for the distribution of the various metabolic types is discussed.

Environmental control of crassulacean acid metabolism in Welwitschia mirabilis Hook. Fil. in its range of natural distribution in the Namib desert

Abstract: Within the area of its natural distribution in South West Africa, Welwitschia mirabilis has a less negative δ13C value than C3 plants and a more negative δ13C value than C4 species. This indicates that Welwitschia m. assimilates CO2 partially via CAM when growing in its natural habitat. The difference between the δ13C values of Welwitschia m. and of the C3 species is significant in the savanna, whereas it is only small and statistically not significant in the grassland zone. The proportion of CO2 fixed via CAM is largest in the coastal desert zone. There was no correlation between the δ13C values and the Cl- or ash content of the tissue. Thus, CAM in Welwitschia m. seems not to be induced by salt stress. There is no change in the δ13C values along the persistent Welwitschia m. leaf. The present data indicate that on a broad geographical scale in the area of distribution temperature regime, and water stress as a modifying factor, determine CAM in Welwitschia m. The ecological implications are discussed by comparing the behaviour of Welwitschia m. with other CAM, C3 and C4 species of the accompanying flora.

Plant Production in Arid and Semi-Arid Areas

Abstract: The determination of phytomass and the assessment of actual and potential primary production of a natural ecosystem has become an important part of modern ecological research. In order to understand the functioning of an ecosystem, to analyse it, and to build valid models (see van Keulen et al., this volume Part 6:B), exact phytomass and production data must be available. This general aim, however, is difficult to approach, since phytomass and primary production are not constant values (see Lieth, this volume Part 6: A). Even for the same habitat they depend upon the total environmental conditions which are changing from year to year. Therefore, the fluctuations of phytomass and production and their relation to the environmental parameters need to be considered. This problem may be of minor importance for ecosystems living in humid environments. It is of great significance, however, in arid and semi-arid areas, where the main factor limiting phytomass and production is the availability of water. It is precisely this factor which in these regions fluctuates to a very large degree from year to year.

An empirical model of net photosynthesis for the desert plant Hammada scoparia (Pomel) Iljin

Abstract: An empirical model for describing daily courses of net photosynthesis in Hammada scoparia is being developed. The model is based on the functional relationships, by which various environmental factors affect the photosynthetic activity and which can be measured by experiment in the field. In a sequence of steady-states daily courses of net photosynthesis are predicted during a growing season considering the variability of the physiological states and the capacity for regulative adaptations. The rate of net photosynthesis at a certain date is calculated from the maximal rate of CO2 uptake being expected at that season and from the effects of light, temperature, and air humidity which are scaled from 0 to 1. All factors are connected multiplicatively. The light function accounts for the seasonal changes in the light curve, the temperature function is based on the seasonal shift of the temperature optimum, and the humidity function considers the increasing sensitivity of the stomatal humidity response at increasing water stress. The model is built to be a submodel of a general ecosystem model, where various other submodels (i.e. water stress model, phenology model) are supplied. The present model is tested by predicting daily courses at extreme climatic conditions during the year and by comparing the predicted values of gas exchange with values being measured in an independent experimental procedure. The result shows that the model is able to simulate the natural behaviour of Hammada scoparia during the growing and dry season of a desert habitat. The problems of incorporating the influence of water stress, the interaction of the various factors, and the phenological aspect of the photosynthetic activity is being discussed.

Distributional pattern of water relations and net photosynthesis of Hammada scoparia (Pomel) Iljin in a desert environment

Abstract: In the Central Negev, the arido-active Hammada scoparia (Chenopodiaceae) is mainly distributed in runnels and loessial plains of the wadis and exists with fewer and smaller individuals on slopes and tops of the neighboring hills. At the end of the dry season, water relations and chloride content of plants from these habitats and of artificially irrigated plants were determined and compared with plant shape and photosynthetic activity. The osmotic potentials and total water potentials of the plants differ characteristically with certain groups of stands. The simultaneously determined range of noon water potentials of the plants within a transect is as high as the annual amplitude of one plant individuum in the wadi (about 45 bars). Plants in the runnel of the wadi show, like the irrigated plants, the highest values of water potentials and their components but markedly lower chloride content than the irrigated ones. Total water and osmotic potentials of plants of the loessial wadi plains are extremely low. Their chloride content is not very high in contrast to that of plants of the hillslope and hilltop. Hill plants, although poorly developed and scarcely branched, have higher water and osmotic potentials than those of the plains. Net photosynthesis of a plant on a natural stand of the wadi plain is, in September, markedly depressed at noon but maximal at noon in an artificially irrigated plant. In contrast to irrigated and nonirrigated wadi plants, a plant of the hillslope shows, already in July, a midday depression of photosynthesis. Whether the relatively low water potentials of the big plants of the loessial plains are the results of a rapid biomass production in the rainy season which might have caused a very strong exhaustion of the soil water reserves for the late summer is discussed. Hill plants do not grow so well and obviously decrease their water exchange even in summer.

Der Säurestoffwechsel von Welwitschia mirabilis Hook. Fil. Am Natürlichen Standort in der Namib Wüste

Abstract: Within the area of its natural distribution in Southwest Africa, Welwitschia mirabilis has a higher ∂13 C value than C3 plants and a lower ∂13 C value than C 4 plants occuring in the same habitat. This indicates that Welwitschia m. fixes part of its carbon by crassulacean acid metabolism (CAM) when growing in its natural habitat. Measurements of ∂13 C values show the proportion of carbon fixed by CAM to be higher in the savanna zone than in the subtropical grassland zone. Even higher ∂13 C values were measured on Welwitschia m. in the coastal desert. There was no correlation between ∂13 C values and the ash content of plant material and with water stress indicating that these factors were not responsible for the observed shift in carbon metabolism. It was concluded, after an analysis of temperature conditions, that cool night temperatures were possibly responsible for promoting a greater portion of CAM in Welwitschia m. in the coastal desert as compared with savanna and subtropical grassland zones.