Transpiration of greenhouse crops : an aid to climate management
01 Jan 1987-
TL;DR: In this paper, physical aspects of greenhouse climate are analyzed to show the direct interrelation between microclimate and crop transpiration, and it is shown that defining the transpiration rate as the criterion for the control of air humidity within a greenhouse would deliver a quantitative framework for that control.
Abstract: In this book some physical aspects of greenhouse climate are analyzed to show the direct interrelation between microclimate and crop transpiration. The energy balance of a greenhouse crop is shown to provide a sound physical framework to quantify the impact of microclimate on transpiration and to identify the constraints set on climate management by the termodynamic behaviour of the canopy. Before the relationship among microclimate, canopy temperature and transpiration is rendered in mathematical terms, a good deal of experimental work is necessary to establish sub-models for the heat transfer of the foliage, for the radiative transfer within the canopy and for the canopy resistance to vapour transfer. The sub-models are merged in a combination-type equation to obtain the temperature of a greenhouse crop and its transpiration. The resulting estimates are shown to reproduce accurately the temperature and transpiration of a greenhouse tomato crop, as measured at time intervals of a few minutes. To illustrate the practical application of the model thus developed a number of examples are presented. In particular, it is shown that defining the transpiration rate as the criterion for the control of air humidity within a greenhouse would deliver a quantitative framework for that control. That would largely enhance the efficiency of the (expensive) procedures applied at present for the control of humidity in greenhouses.
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TL;DR: In this article, the authors present the state of the art on both the above technologies, when applied in the city scale, and present the definition of the limits, the boundaries and the conditions under which the considered technologies reach their better performance in a synthetic way.
1,204 citations
TL;DR: Thermography is shown to be more than just a method for obtaining pretty pictures; it has particular advantages for the quantitative analysis of spatial and dynamic physiological information.
Abstract: The applications of remote temperature sensing of plants by infrared thermography and infrared thermometry are reviewed and their advantages and disadvantages for various purposes discussed. The great majority of applications of thermography and of infrared thermometry depend on the sensitivity of leaf temperature to evaporation rate (and hence to stomatal aperture). In most applications, such as in the early or pre-symptomatic detection of disease or water deficits, what is actually being studied is the effect of the disease on stomatal behaviour or membrane permeability to water. Other applications of thermography in plant physiology include the study of thermogenesis as well as the characterisation of boundary layer transfer processes. Thermography is shown to be more than just a method for obtaining pretty pictures; it has particular advantages for the quantitative analysis of spatial and dynamic physiological information. Its capacity for large throughput has found application in screening approaches, such as in the selection of stomatal or hormonal mutants. The use of wet and dry reference surfaces for the enhancement of the power of thermal imaging approaches, especially in the field is reviewed, and the problems and potential solutions when applying thermography in the field and in the laboratory discussed.
222 citations
01 Jan 1977
TL;DR: A large body of theoretical work has been developed in attempts to understand and predict phenomena of the sort described in the previous chapter as discussed by the authors, but the physical argument provides no precise information about when the instability will occur and also provides little indication of the detailed structure of the motion resulting from the instability.
Abstract: A large body of theoretical work has been developed in attempts to understand and predict phenomena of the sort described in the previous chapter. In most cases the cause of the instability can be formulated in a way that gives some physical understanding of the processes involved. However, this is usually opposed by some stabilizing process, such as the damping action of viscosity, and the physical argument provides no precise information about when the instability will occur. It also provides little indication of the detailed structure of the motion resulting from the instability.
212 citations
01 Jan 1996
TL;DR: In this article, a simulation model is presented that can be used as a tool to judge the energy-saving measures proposed in greenhouse gardening, and the results of the model on these options with respect to energy consumption and biomass production are compared with a reference situation.
Abstract: Greenhouse Horticulture in the Netherlands has set itself the task of having halved its primary energy consumption per unit of production at the end of the century, compared to 1980. As a result, a large number of energy-saving measures have been suggested to meet this target. In this book a simulation model is presented that can be used as a tool to judge the measures proposed. The model describes the dynamics of the greenhouse climate, the components of the heating system and the greenhouse climate controller with a time resolution of up to 1 minute. Also, the photosynthetic activity of the canopy is described. Consequently the model takes account for the complicated horticultural practice. The simulation model is constructed from sub-models. Each of these sub-models is discussed in detail. The sub-models for the heating circuit, the condenser and the short-term heat storage facility were newly developed. Therefore, these parts of the model are discussed extensively. The greenhouse climate controller and the greenhouse climate simulation are described integrally, however briefly, because these parts of the model are a reflection of the current state-of-the-art. To proof the quality of the simulation model, computations are compared to measurements on a rose crop in a research facility. These comparisons are made both with a high resolution on a small time scale (10 minutes) and with aggregated values on a large time scale (year round daily results). To analyze the prospects of energy-saving measures in greenhouse cultivation, the simulation model was applied to nine energy-saving options. The results of the model on these options with respect to energy consumption and biomass production are compared with a reference situation. The reference situation comprised a customary greenhouse growing tomatoes in the Netherlands. From the options evaluated, the application of combined heat and power and alternative cladding materials appeared to yield the largest decrement of specific energy consumption (the energy consumption corrected for production effects).
186 citations
01 Jan 1994
TL;DR: An explanatory dynamic growth model was developed that simulates assimilate demand and dry matter distribution in an indeterminate tomato crop and it was found that in spring and early summer the optimum plant density is determined by the required number of fruits whereas in summer a combination of high plant density and fruit thinning seems required for sufficient leaf area.
Abstract: In the glasshouse cultivation of a long-season tomato crop, maximum fruit production is obtained when there is a proper balance between the demand and the supply of assimilate, and an optimum proportion of vegetative growth throughout the season in order to sustain the crop photosynthetic capacity. These aspects of crop growth are mainly affected by the fruit load, defined as the assimilate demand of all fruits together. In practice fruit load is controlled by plant density, fruit thinning and temperature. These measures for crop control can be more precise and effective if their effects are known in quantitative terms. An explanatory dynamic growth model was developed that simulates assimilate demand and dry matter distribution in an indeterminate tomato crop. Number of growing organs was evaluated through prediction of initiation, abortion and harvest of individual organs. Assimilate demand was based on potential organ growth rates (growth at nonlimiting assimilate supply). Dry matter distribution in the model was in proportion to the potential growth rates of the organs.In total 11 glasshouse experiments were conducted, six of which included temperature treatments. Truss formation rate increased with temperature (17-27°C) and declined with plant age. Truss formation rate was found to depend on the genotype, while fruit load, plant density, season and electrical conductivity of the root environment (EC: 0.3-0.9 S m -1 ) had no effect. The number of fruit that develop per truss was positively correlated with the vegetative growth of the top of the plants. The duration of the fruit growth period (time between anthesis and start of colouring) was shortened with increasing temperature, young and old fruits being the most sensitive. At the same air temperature the fruit growth period in summer was shorter than in spring. Fruits of old plants had slightly longer growth period than fruits of young plants. Potential weight of the fruits at harvest was negatively correlated with temperature, mainly due to the shorter fruit growth period. Further, the potential size increased with ontogeny, which effect was more pronounced in early than in late spring. The course of potential weight in time was described by a Gompertz growth curve exhibiting the maximum growth rate at about 40% of the fruit growth period. When during fruit development a fruit changed from limiting to nonlimiting assimilate supply, it did not immediately reach the same growth rate as fruits grown constantly at nonlimiting assimilate supply., A mechanism is proposed that explains this phenomenon. The fraction of dry matter distributed to vegetative growth declined substantially with temperature. The (apparent) potential growth rate of a vegetative unit at 24°C was estimated to be as much as 50% lower than at 19°C. The dry matter-content of fruits was negatively correlated with temperature and EC of the root environment and was higher in summer than in spring and autumn.The model was tested with data from five commercial crops. Truss formation rate, fruit growth period and dry matter distribution were predicted reasonably well. The modelling of the number of fruits per truss requires more investigation. Simulated assimilate demand of a mature tomato crop reached values of 10 and 60g CH 2 O m -2 d -1 for maintenance respiration and growth respectively. The potential growth rate (as defined by the sinks) appeared to be about twice the actual growth rate.A simulation study indicated that maximum fruit production of tomato is probably obtained at a fairly low leaf area index (2-3 m 2 m -2 ). At supra-optimum leaf area index additional leaf area for extra light interception requires more assimilate than it would produce. Computations showed that in spring and early summer the optimum plant density is determined by the required number of fruits (sink capacity) whereas in summer a combination of high plant density and fruit thinning seems required for sufficient leaf area. The results are discussed with respect to the crop sink-source system and temperature control in the glasshouse. Prospects for practical applications of the model are presented.
178 citations
References
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TL;DR: It is shown that a satisfactory account can be given of open water evaporation at four widely spaced sites in America and Europe, the results for bare soil receive a reasonable check in India, and application of theresults for turf shows good agreement with estimates of evapolation from catchment areas in the British Isles.
Abstract: Two theoretical approaches to evaporation from saturated surfaces are outlined, the first being on an aerodynamic basis in which evaporation is regarded as due to turbulent transport of vapour by a process of eddy diffusion, and the second being on an energy basis in which evaporation is regarded as one of the ways of degrading incoming radiation. Neither approach is new, but a combination is suggested that eliminates the parameter measured with most difficulty—surface temperature—and provides for the first time an opportunity to make theoretical estimates of evaporation rates from standard meteorological data, estimates that can be retrospective. Experimental work to test these theories shows that the aerodynamic approach is not adequate and an empirical expression, previously obtained in America, is a better description of evaporation from open water. The energy balance is found to be quite successful. Evaporation rates from wet bare soil and from turf with an adequate supply of water are obtained as fractions of that from open water, the fraction for turf showing a seasonal change attributed to the annual cycle of length of daylight. Finally, the experimental results are applied to data published elsewhere and it is shown that a satisfactory account can be given of open water evaporation at four widely spaced sites in America and Europe, the results for bare soil receive a reasonable check in India, and application of the results for turf shows good agreement with estimates of evaporation from catchment areas in the British Isles.
6,711 citations
Journal Article•
TL;DR: Progress towards a reconciliation of parallel concepts in meteorology and physiology is described, which stresses the importance of physiological restraint on the rate of transpiration from an irrigated field surrounded by dry land.
Abstract: A turgid leaf exposed to bright sunshine can transpire an amount of water several times its own weight during a summer day. Rapid evaporation is sustained by a supply of heat from the atmosphere and by a movement of water within the plant preventing the desiccation of leaf tissue. In analysis, the need for energy and the need for water have often been disassociated. Meteorologists investigating the energetics of transpiration have assumed that leaves behave like pieces of wet, green blotting paper, and plant physiologists have demonstrated mechanisms for the conduction of water at arbitrary rates unrelated to the physics of the environment. This paper describes progress towards a reconciliation of parallel concepts in meteorology and physiology. The path for the diffusion of water vapour from leaf cells to the free atmosphere is divided into two parts, one determined primarily by the size and distribution of stomata, and the other by wind speed and the aerodynamic properties of the plant surface. Diffusive resistances for single leaves and for plant communities are established from measurements in the laboratory and in the field and are then used: (i) to predict relative rates of evaporation from leaves with wet and dry surfaces; (ii) to investigate the dependence of transpiration rate on wind speed and surface roughness; (iii) to demonstrate that the relation between transpiration rate and lead area is governed by stomatal closure in leaves well shaded from sunlight; (iv) to calculate maximum rates of transpiration for different crops and climates. A final section on the convection of dry air stresses the importance of physiological restraint on the rate of transpiration from an irrigated field surrounded by dry land.
4,686 citations
TL;DR: In this paper, the second edition of the Second edition, the authors present a list of symbolic symbols for the field of environmental physical sciences, including the following: 1.GAS LAWS Pressure, volume and temperature Specific heats Lapse rate Water and water vapour Other gases 3. TRANSPORT LAWS General transfer equation Molecular transfer processes Diffusion coefficients Radiation laws 4. RADI ENVIRONMENT Solar radiation Terrestrial radiation Net radiation 5. MICROCLIMATOLOGY OF RADIATION (i) Interception Direct solar radiation Diffuse radiation Radiation in
Abstract: PREFACE TO THE SECOND EDITION LIST OF SYMBOLS 1. SCOPE OF ENVIRONMENTAL PHYSICS 2. GAS LAWS Pressure, volume and temperature Specific heats Lapse rate Water and water vapour Other gases 3. TRANSPORT LAWS General transfer equation Molecular transfer processes Diffusion coefficients Radiation laws 4. RADIATION ENVIRONMENT Solar radiation Terrestrial radiation Net radiation 5. MICROCLIMATOLOGY OF RADIATION (i) Interception Direct solar radiation Diffuse radiation Radiation in crop canopies 6. MICROCLIMATOLOGY OF RADIATION (ii) Absorption and reflection Radiative properties of natural materials Net radiation 7. MOMENTUM TRANSFER Boundary layers Wind profiles and drag on uniform surfaces Lodging and windthrow 8. HEAT TRANSFER Convection Non-dimensional groups Measurements of convection Conduction Insulation of animals 9. MASS TRANSFER (i) Gases and water vapour Non-dimensional groups Measurement of mass transfer Ventilation Mass transfer through pores Coats and clothing 10.MASS TRANSFER (ii) Particles Steady motion 11.STEADY STATE HEAT BALANCE (i) Water surfaces and vegetation Heat balance equation Heat balance of thermometers Heat balance of surfaces Developments from the Penman Equation 12.STEADY STATE HEAT BALANCE (ii) Animals Heat balance components The thermo-neutral diagram Specification of the environment Case studies 13.TRANSIENT HEAT BALANCE Time constant General cases Heat flow in soil 14.CROP MICROMETEOROLOGY (i) Profiles and fluxes Profiles Profile equations and stability Measurement of flux above the canopy 15.CROP MICROMETEOROLOGY (ii) Interpretation of measurements Resistance analogues Case studies: Water vapour and transpiration Carbon dioxide and growth Sulphur dioxide and pollutant fluxes to crops Transport within canopies APPENDIX BIBLIOGRAPHY REFERENCES INDEX
4,087 citations
TL;DR: In this paper, the stomatal conductance of illuminated leaves is a function of current levels of temperature, vapour pressure deficit, leaf water potential (really turgor pressure) and ambient CO $_2$ concentration and when plotted against any one of these variables a scatter diagram results.
Abstract: Attempts to correlate values of stomatal conductance and leaf water potential with particular environmental variables in the field are generally of only limited success because they are simultaneously affected by a number of environmental variables. For example, correlations between leaf water potential and either flux of radiant energy or vapour pressure deficit show a diurnal hysteresis which leads to a scatter diagram if many values are plotted. However, a simple model may be adequate to relate leaf water potential to the flow of water through the plant. The stomatal conductance of illuminated leaves is a function of current levels of temperature, vapour pressure deficit, leaf water potential (really turgor pressure) and ambient CO $_2$ concentration. Consequently, when plotted against any one of these variables a scatter diagram results. Physiological knowledge of stomatal functioning is not adequate to provide a mechanistic model linking stomatal conductance to all these variables. None the less, the parameters describing the relationships with the variables can be conveniently estimated from field data by a technique of non-linear least squares, for predictive purposes and to describe variations in response from season to season and plant to plant.
2,897 citations
01 Jan 1986
TL;DR: In this paper, a methodology to quantify yield response to water through aggregate components which form the "handles" to assess crop yields under both adequate and limited water supply is presented, which takes into account maximum and actual crop yields as influenced by water deficits using yield response functions relating relative yield decrease and evapotranspiration deficits.
Abstract: This publication presents a methodology to quantify yield response to water through aggregate components which form the "handles" to assess crop yields under both adequate and limited water supply. The method presented in part A takes into account maximum and actual crop yields as influenced by water deficits using yield response functions relating relative yield decrease and evapotranspiration deficits. Part B gives an account of water-related crop yield and quality information for 26 crops
2,680 citations